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3,500
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Onset heart rate of microvolt-level T-wave alternans provides clinical and prognostic value in nonischemic dilated cardiomyopathy.
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This study was designed to determine the prognostic value of onset heart rate (OHR) in T-wave alternans (TWA) in patients with nonischemic dilated cardiomyopathy (DCM).</AbstractText>One of the current major issues in DCM is to prevent sudden cardiac death (SCD). However, the value of the OHR of TWA as a prognostic indicator in DCM remains to be elucidated.</AbstractText>We prospectively investigated 104 patients with DCM undergoing TWA testing. The end point of this study was defined as SCD, documented sustained ventricular tachycardia/ventricular fibrillation. Relations between clinical parameters and subsequent outcome were evaluated.</AbstractText>Forty-six patients presenting with TWA were assigned to one of the following two subgroups according to OHR for TWA of < or = 100 beats/min: group A (n = 24) with OHR < or = 100 beats/min and group B (n = 22) with 100 < OHR < or = 110 beats/min. T-wave alternans was negative in 37 patients (group C) and indeterminate in 21 patients. The follow-up result comprised 83 patients with determined TWA. During a follow-up duration of 21 +/- 14 months, there was a total of 12 arrhythmic events, nine of which included three SCDs in group A, two in group B and one in group C. The forward stepwise multivariate Cox hazard analysis revealed that TWA with an OHR < or = 100 beats/min and left ventricular ejection fraction were independent predictors of these arrhythmic events (p = 0.0001 and p = 0.0152, respectively).</AbstractText>The OHR of TWA is of additional prognostic value in DCM.</AbstractText>
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3,501
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Pregnancy after fontan repair of complex congenital heart disease.
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We describe four successful pregnancies in three women who had previously had a Fontan repair for congenital heart disease. Each pregnancy resulted in a live birth and there was no maternal mortality The infants were premature, being delivered at 26, 30 and 35 weeks, and weighing 1,020, 1,333 and 1,930 g respectively The fourth infant was born at 32 weeks and no birthweight is available. Maternal complications occurred and were those anticipated after a Fontan repair. Two mothers required treatment for supraventricular arrhythmias (atrial flutter and fibrillation). Ventricular failure was present in two mothers and required ongoing drug treatment. Raised systemic venous pressures caused peripheral oedema in two mothers and hepatomegaly and ascites in one mother. The physiology, potential complications, anaesthetic concerns and drug treatment in pregnancy after Fontan repair are discussed.
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3,502
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Differentiation of atrial rhythms from the electrocardiogram with coherence spectra.
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Automated electrocardiogram (ECG) interpretation systems fail to reliably discriminate atrial fibrillation from sinus rhythm and other more regular atrial arrhythmias. Previously, magnitude-squared coherence (MSC), a frequency domain measure of the linear phase relation between 2 signals, has been shown to be a reliable discriminator of fibrillatory and nonfibrillatory cardiac rhythms when applied to intracardiac electrograms. This study determines whether MSC, when applied to the surface electrocardiogram, would discriminate between atrial fibrillation and nonfibrillatory atrial rhythms. MSC was analyzed by using 2 surface leads of a 10-second ECG. For 68 ECG recordings (23 sinus rhythm, 22 atrial flutter, and 23 atrial fibrillation), MSC was computed between leads II and V1 and the mean MSC in several frequency bands was examined. The performance of MSC was compared to previously published measures of ventricular irregularity and percent power in discriminating atrial fibrillation from nonfibrillatory rhythms. As hypothesized, atrial fibrillation exhibited low coherence in the 2 to 9 Hz band while nonfibrillatory atrial rhythms exhibited relatively moderate to high levels of coherence in the same frequency band. Mean MSC in the 2 to 9 Hz band was significantly lower for atrial fibrillation (range, 0.04 to 0.48; mean +/- SD: 0.15 +/- 0.11) than for sinus rhythm (range, 0.18 to 0.81; 0.47 +/- 0.17) (P <.0005) and atrial flutter (range, 0.06 to 0.80; 0.44 +/- 0.21) (P <.0005). Mean MSC in the 2 to 9 Hz band showed less overlap between atrial fibrillation and atrial flutter than R-R variability and percent power. However, R-R variability showed less overlap between atrial fibrillation and sinus rhythm than mean MSC and percent power. Thus, MSC and RRV both discriminate atrial fibrillation from more organized atrial rhythms. Conversely, percent power was highly variable for both atrial fibrillation and organized atrial rhythms. Results suggest that MSC applied to surface ECG may be used to quantify rhythm organization.
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3,503
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Expression and intracellular localization of an SCN5A double mutant R1232W/T1620M implicated in Brugada syndrome.
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Brugada syndrome is an inherited cardiac disorder caused by mutations in the cardiac sodium channel gene, SCN5A, that leads to ventricular fibrillation and sudden death. This study reports the changes in functional expression and cellular localization of an SCN5A double mutant (R1232W/T1620M) recently discovered in patients with Brugada syndrome. Mutant and wild-type (WT) human heart sodium channels (hNa(v)1.5) were expressed in tsA201 cells in the presence of the beta(1)-auxiliary subunit. Patch-clamp experiments in whole-cell configuration were conducted to assess functional expression. Immunohistochemistry and confocal microscopy were used to determine the spatial distribution of either WT or mutant cardiac sodium channels. The results show an abolition of functional sodium channel expression of the hNa(v)1.5/R1232W/T1620M mutant in the tsA201 cells. A conservative positively charged mutant, hNa(v)1.5/R1232K/T1620M, produced functional channels. Immunofluorescent staining showed that the FLAG-tagged hNa(v)1.5/WT transfected into tsA201 cells was localized on the cell surface, whereas the FLAG-tagged hNa(v)1.5/R1232W/T1620M mutant was colocalized with calnexin within the endoplasmic reticulum (ER). These results indicate that a positively charged arginine or lysine residue at position 1232 in the double mutant is required for the proper transport and functional expression of the hNa(v)1.5 protein. These results support the concept that loss of function of the cardiac Na(+) channel is responsible for the Brugada syndrome. The full text of this article is available at http://www.circresaha.org.
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3,504
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Electrocardiographic measures of repolarization revisited: why? what? how?
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Ventricular repolarization continues to be an enigma to clinical cardiologists and cardiac electrophysiologists. On the one hand, a century of experience has documented an association between abnormal T-wave morphology, QT prolongation and dispersion, T-wave alternans, and nonspecific ST-T waves with arrhythmia risk or negative prognostic outcome. On the other hand, recent advances in molecular electrophysiology have definitively implicated abnormal function and structure of cardiac ion channels associated with repolarization as primary arrhythmogenic mechanisms in long QT syndrome, Brugada's Syndrome, and idiopathic ventricular fibrillation and ventricular tachycardia. In spite of this extensive clinical experience and newly established mechanistic knowledge, robust measurements of repolarization and sensitive algorithms for reliable assessment of risk and prediction of arrhythmia occurrence have remained elusive. New insights into electrocardiographic waveform that reflect and capture the underlying spatial and dynamic characteristics of repolarization offer opportunity to devise clinical indices of repolarization that might be more predictive of risk or outcome than those currently used. Experimental and model data show evidence that the location and size of repolarization lesions may be deduced from T waveform. The changes of repolarization induced by altered activation sequence, and cycle length mediated alterations to repolarization offer additional means to assess the magnitude and significance of such lesions that are linked to increased arrhythmogenic risk. This article explores indices of repolarization that are sensitive to repolarization and its change and that provide opportunity to better characterize and assess repolarization for risk stratification.
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3,505
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Molecular biology and cellular mechanisms of Brugada and long QT syndromes in infants and young children.
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Sudden cardiac death accounts for 19% of sudden deaths in children between 1 and 13 years of age and 30% of sudden deaths that occur between 14 and 21 years of age. The incidence of sudden cardiac death displays 2 peaks: one between 45 and 75 years of age, as a result of coronary artery disease, and the other between birth and 6 months of age, caused by sudden infant death syndrome. The role of cardiac arrhythmias in sudden infant death syndrome has long been a matter of debate and the role of cardiac arrhythmias in children in general is not well defined. Recent findings point to a contribution of primary electrical diseases of the heart including the Brugada and long QT syndromes to sudden death in infants and children. Mutations in SCN5A and HERG and KvLQT1 have been shown to be associated with life-threatening arrhythmias and long QT intervals in young infants. These mutations cause changes in sodium and potassium currents that amplify intrinsic electrical heterogeneities within the heart, thus providing a substrate as well as a trigger for the development of reentrant arrhythmias, including Torsade de Pointes (TdP), commonly associated with the long QT syndrome (LQTS). Mutations in SCN5A have also been shown to cause the sodium channel to turn off prematurely and thus to set the stage for the development of a rapid polymorphic ventricular tachycardia/ventricular fibrillation in patients with the Brugada Syndrome. In LQTS, ion channel mutations cause a preferential prolongation of the M cell action potential that contributes to the development of long QT intervals, wide-based or notched T waves, and a large transmural dispersion of repolarization, which provides the substrate for the development of TdP. An early afterdepolarization-induced triggered beat is thought to provide the extrasystole that precipitates TdP. In the Brugada syndrome, mutations in SCN5A reduce sodium current density, causing premature repolarization of the epicardial action potential due to an all or none repolarization at the end of phase 1. The loss of the action potential dome in epicardium, but not endocardium, creates a dispersion of repolarization across the ventricular wall, resulting in a transmural voltage gradient that manifests in the electrocardiogram (ECG) as an ST-segment elevation and in the development of a vulnerable window during which reentry can be induced. Under these conditions, loss of the action potential dome at some epicardial sites but not others gives rise to phase 2 reentry, which provides an extrasystole capable of precipitating ventricular tachycardia/ventricular fibrillation (or rapid TdP). The practical importance of identifying infants and children with Brugada and LQTS syndromes lies in the fact that most deaths due to these congenital defects can be prevented. A simple ECG is often sufficient to permit diagnosis and thus to prevent the development of life-threatening arrhythmic events. Mass ECG screening of neonates and children however has been the subject of debate focused on issues ranging from the emotional impact of dealing with false positives to those concerning socio-economic and medico-legal factors. These issues are discussed in other articles. These concerns notwithstanding, it is important that we continue to question whether the economic inefficiencies of current screening methodologies supersede the value of a young life.
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3,506
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Catecholamines in children with congenital long QT syndrome and Brugada syndrome.
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Catecholamines have long been used as a provocative test in some forms of tachyarrhythmias including long QT syndrome (LQTS). In contrast, catecholamines are reported to decrease ST-segment elevation in leads V1-V3 in some patients with Brugada syndrome. Differential effects of catecholamines on QT interval, action potential duration, transmural dispersion of repolarization and Torsade de Pointes between LQT1, LQT2, and LQT3 forms of the LQTS were shown in experimental models of the LQTS by using arterially-perfused wedge preparations as well as in patients with congenital LQTS including children. In our preliminary result of patients with Brugada syndrome including a child, isoproterenol infusion was effective to decrease the ST-segment elevation in leads V1-V2 and to suppress the electrical storm of ventricular fibrillation.
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3,507
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Effect of radiofrequency current on previously implanted pacemaker and defibrillator ventricular lead systems.
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We compared the response of endocardial lead systems to radiofrequency (RF) current delivered during atrio-ventricular junction ablation (AVJA) for atrial fibrillation with uncontrolled ventricular rate in 107 patients. The mean age was 67 +/- 11 years and the mean ejection fraction 42 +/- 15%. Patients were divided into 3 groups based on the type of ventricular lead present at the time of ablation: a previously implanted defibrillator lead (group 3, n = 13), a previously implanted pacemaker lead (group 2, n = 46) or a temporary lead (group 1, n = 48), which was subsequently followed by a permanent lead implantation. During AVJA, a median of 5 RF applications (44 +/- 8 W) were given via 4-5-mm electrodes. All but 1 patient had right-sided lesions, while 6 patients also had left sided lesions. Ventricular pacing thresholds were evaluated immediately pre- and post-ablation at 24 hours and at 1 to 3 months. Increases in ventricular pacing voltage thresholds were noted in all 3 groups over time, with the greatest mean increase in group 3 patients: [table: see text]. A greater than 2-fold increase in pacing thresholds was observed only with previously implanted leads, usually within the first 48 hours. It occurred significantly more often in patients with group 3 (6/13 [46%]) compared to group 2 (6/46 [13%], odds ratio 7.6, P = 0.006). A progressive rise in pacing threshold required lead revision in 2/13 group 3 patients (15%) and 2/46 group 2 patients (4%). While RF current has only minor effects on pacing threshold in most patients with previously implanted ventricular lead systems, clinically important alterations requiring device reprogramming or lead revision may occur. Group 3 are significantly more vulnerable to RF current, though the mechanisms are unclear. Group 1 during AVJA, followed by permanent lead implantation appears advisable. Pts with a previously implanted group 3 who require AVJA should be monitored closely.
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3,508
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T-wave morphology differences between patients with and without arrhythmic complication of ischemic heart disease.
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The study investigated the differences in T-wave morphology between normal controls, patients with an uncomplicated follow-up after a myocardial infarction (MI), and patients with ischaemic heart disease and a history of ventricular tachycardia/fibrillation (VT/VF). The study population consisted of 164 healthy patients (age 53.4 +/- 18.7 years old, 80 women), 123 VT/VF patients (age 63.8 +/- 10.1 years old, 15 women), and 196 MI patients (age 59.2 +/- 10.0 years old, 23 women). In all patients, supine resting signal-averaged orthogonal electrocardiograms were obtained. After singular value decomposition of electrocardiogram signal, 2 T-wave morphology descriptors were calculated: total cosine R to T describing the global angle between repolarisation and depolarisation loops, and percentage of loop area expressing the irregularity of the T-wave loop (a more irregular wave results in a lower percentage of loop area value). Both parameters were practically uncorrelated (Controls: r = - .106, MI r = .161, and VT/VF r = .173) and different between individual groups of patients: total cosine R to T (Control vs. MI: P = 4.3 x 10(-8), Control vs. VT/VF: P = 2.7 x 10(-16), MI vs. VT/VF: P = 3.1 x 10(-6)), percentage of loop area (Control vs. MI: P = 0.07, Control vs. VT/VF: P = 1.1 x 10(-8), MI vs. VT/VF: P = 2.9 x 10(-5), all nonparametric Mann-Whitney test). The comparisons of cumulative histograms also revealed significant differences between all three groups for both parameters (Kruskal-Wallis ANOVA test). Thus, these numerical descriptors of T-wave morphology are powerful indicators of arrhythmic complications among patients with ischaemic heart disease. They also differentiate between patients with stable uncomplicated ischaemic heart disease and healthy controls.
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3,509
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Predictive value of T-wave morphology variables and QT dispersion for postmyocardial infarction risk assessment.
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Different attempts have been made to use the 12-lead surface electrocardiogram (ECG) for risk stratification of patients prone to sudden cardiac death. Among others, QT dispersion (QTd) has been proposed as a simple risk marker, eg, in patients postmyocardial infarction (MI). To overcome the methodological limitations of QTd, novel T-wave morphology variables have been recently developed based on technologies that better quantify the substrate of a pathologically changed repolarization. In 280 post-MI patients with 27 events (death or nonfatal sustained ventricular tachycardia/ventricular fibrillation) during long-term follow-up (32 +/- 10 months), a 12-lead ECG was recorded before discharge and converted into a digital format. The prognostic value of digitally measured QTd and other conventional variables, and that of novel ECG variables of T-wave loop morphology was assessed. The latter included fully automatic and reproducible analysis of variables defining spatial and temporal T-wave variation as well as its wavefront direction. Among the 5 variables studied, the total cosine R to T (TCRT--describing the global angle between repolarization and depolarization orientations) and the T-wave loop dispersion were univariately associated (P = .0002 and P < .002) with events. Comparison of Kaplan Meier curves for patient strata above and below the median confirmed the strong discrimination of risk by TCRT and T-wave loop dispersion values (P < .003 and P < .001). On Cox regression analysis entering other univariately predictive risk stratifiers including age, left ventricular ejection fraction, heart rate, reperfusion therapy, beta adrenergic blocker treatment, and SDNN from Holter, TCRT (P < .03) yielded independent predictive value while T-wave loop dispersion was of borderline independence (P = .064). Heart rate (P < .02), left ventricular ejection fraction (P < .02), and reperfusion therapy (P <.02) also remained in the final model. In contrast, none of the conventional variables of repolarization dispersion including QTd and rate-corrected QTd revealed prognostic value on univariate or Kaplan Meier analysis despite optimized digital processing techniques. Computerized analysis of T-wave loop morphology from the 12-lead resting ECG permits independent assessment of post-MI risk and should replace the poorly conceptualized measurement of QTd.
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3,510
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Clinical and familial study of arrhythmogenic right ventricular cardiomyopathy.
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To explore the characteristics of arrhythmogenic right ventricular cardiomyopathy (ARVC).</AbstractText>Seven patients with arrhythmogenic right ventricular cardiomyopathy and 34 members of three families were studied. All patients and family members underwent history collection, clinical examination, electrocardiogram (ECG), two-dimensional echocardiography (2-DE) and a signal averaging electrocardiogram. Programmed ventricular stimulation was performed in five patients.</AbstractText>All patients and family members had normal morphologic characteristics and normal function of the left ventricular by 2-DE. Fourteen persons had abnormal findings indicating ARVC. Five had enlargement of the right ventricular with diffused hypocontractility, eight had thin and systolic bulging in the focal anterior wall with hypokinesia and one had bulging of the inferior wall. Twenty-five persons (seven patients and 18 family members) had abnormal findings in ECG. Positive ventricular late potential was recorded in 13 persons (six patients). Two to three monomorphic ventricular tachycardia (VT) with left bundle branch block (LBBB) configurations were induced in five patients. Ventricular fibrillation was induced in two patients during the electrophysiologic study (EPS). Five patients had very high pacing threshold and/or ineffective pacing in one or many regions of the right ventricle. Two members of one family died suddenly. One member was a dwarf with ARVC. Spontaneous VT with a left bundle branch block (LBBB) configuration was recorded in five patients, polymorphic VT with extremely short coupling interval in one, and premature ventricular complexes with LBBB configuration in 12 (six patients).</AbstractText>Our familial study strongly suggests that ARVC may be a hereditary disease and it is helpful in the diagnosis and detection of ARVC. The most common manifestations were abnormal structure and function of the right ventricle and abnormal ECG of repolarization and ventricular arrhythmia which originates from the right ventricle.</AbstractText>
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3,511
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Implantation of dual chamber pacemaker defibrillator and placement of endocardial leads via the axillary vein.
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To assess the preliminary clinical results of implantation of dual chamber pacemaker defibrillator and to evaluate the safety and effectiveness of placement of endocardial leads in the axillary vein.</AbstractText>Seven patients with ventricular tachycardia and/or ventricular fibrillation (VT/VF), associated with bradyanhythmia received implantation of a dual chamber pacemaker defibrillator, including 5 patients with coronary artery disease and 2 patients with dilated cardiomyopathy. The atrial and ventricular leads were introduced via the axillary vein under venographic guidance.</AbstractText>Dual chamber pacemaker defibrillators were successfully implanted in the left chest subcutaneous pocket in 5 patients and the left pectoral muscular pocket in 2 patients. All the VT/VF occurring either inducibly during the procedure or spontaneuously during follow-up were detected promptly and treated successfully. Both the pacing and sensing functions were satisfactory. The endocardial leads required were successfully introduced via the axillary vein without major complications.</AbstractText>Dual chamber pacemaker defibrillators can provide reliable therapy for VT/VF and the dual chamber pacing function. Placement of endocardial leads via the axillary vein under venographic guidance is safe and effective.</AbstractText>
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3,512
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Predisposing conditions for atrial fibrillation in atrial septal defect with and without operative closure.
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The aims of this study were to determine the prevalence and predisposing conditions for atrial fibrillation (AF) in adults with atrial septal defect (ASD) and to evaluate the influence of age at surgical repair. The study population consisted of 286 adults with ASD (mean age 39.5 +/- 19 years). All patients had >or = 1 follow-up visit and a Doppler echocardiographic study. One hundred ninety-two of the patients underwent surgical closure 1 to 34 years before the study. Analyzed variables were entered into univariate (Mann-Whitney U) and multivariate (stepwise logistic regression) models to assess independent predictors for AF. The prevalence of AF was similar in surgically treated patients (15.6%) and in the nonsurgical group (13.8%) (p = 0.69). Multivariate analysis showed that current age (RR 1.9 per each decade of age, 95% confidence interval [CI] 1.3 to 2.7, p = 0.001), mitral regurgitation (RR 3.0 per each degree of regurgitation, 95% CI 1.6 to 5.8, p = 0.001), left atrial enlargement (RR 2.8 per each 10 mm increase in size, 95% CI 1.5 to 5.2, p = 0.001), and tricuspid regurgitation (RR 1.9 per each degree of regurgitation, 95% CI 1.0 to 3.7, p = 0.04) were independent predictors of AF; however, gender, anatomic type, defect size, Qp:Qs, pulmonary artery pressure, right ventricular dimension, left ventricular shortening fraction, and prior surgical repair were not related to late AF development. In the surgical group, age >25 years at the time of surgery was the only predictor for AF independent of age at the time of the study (p = 0.02).
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3,513
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Cardiac arrest and monitoring.
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Initial assessment to determine pulselessness, monitoring the status of the patient, and the effectiveness of resuscitation efforts are integral parts of cardiopulmonary resuscitation. This article focuses on aspects of monitoring during cardiopulmonary resuscitation: electrocardiography and assessment of the adequacy of chest compressions.
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3,514
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A randomised trial to investigate the efficacy of magnesium sulphate for refractory ventricular fibrillation.
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Ventricular fibrillation (VF) remains the most salvageable rhythm in patients suffering a cardiopulmonary arrest (CA). However, outcome remains poor if there is no response to initial defibrillation. Some evidence suggests that intravenous magnesium may prove to be an effective antiarrhythmic agent in such circumstances.</AbstractText>Intravenous magnesium sulphate given early in the resuscitation phase for patients in refractory VF (VF after 3 DC shocks) or recurring VF will significantly improve their outcome, defined as a return of spontaneous circulation (ROSC) and discharge from hospital alive.</AbstractText>A randomised, double blind, placebo controlled trial. Pre-defined primary and secondary endpoints were ROSC at the scene or in accident and emergency (A&E) and discharge from hospital alive respectively. SETTING, PARTICIPANTS, AND INTERVENTION: Patients in CA with refractory or recurrent VF treated in the prehospital phase by the county emergency medical services and/or in the A&E department. One hundred and five patients with refractory VF were recruited over a 15 month period and randomised to receive either 2-4 g of magnesium sulphate or placebo intravenously.</AbstractText>Fifty two patients received magnesium treatment and 53 received placebo. The two groups were matched for most parameters including sex, response time for arrival at scene and airway interventions. There were no significant differences between magnesium and placebo for ROSC at the scene or A&E (17% v 13%). The 4% difference had 95% confidence intervals (CI) ranging from -10% to +18%. For patients being alive to discharge from hospital (4% v 2%) the difference was 2% (95% CI -7% to +11%). After adjustment for potential confounding variables (age, witnessed arrest, bystander cardiopulmonary resuscitation and system response time), the odds ratio (95% CI) for ROSC in patients treated with magnesium as compared with placebo was 1.69 (0.54 to 5.30).</AbstractText>Intravenous magnesium given early in patients suffering CA with refractory or recurrent VF did not significantly improve the proportion with a ROSC or who were discharged from hospital alive.</AbstractText>
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3,515
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[Unexplained right ventricle dilatation clarified by a cardiac contusion many years ago].
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In a 52-year-old man with new onset atrial fibrillation, transthoracic echocardiography showed an isolated, considerably dilated right ventricle. Frequent causes of right ventricular dilatation were ruled out. The image-forming investigation showed an isolated dilation of the ventral part of the heart, which, in combination with a blunt chest trauma 30 years previously, led to a previous cardiac contusion being suspected. In accordance with this hypothesis myocardial scintigraphy showed asymmetric hypertrophy of the right ventricular wall, which is consistent with the remodeling that occurs in response to injured cardiac tissue. After electrical cardioversion sinus rhythm was obtained; the patient remained symptom free.
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3,516
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Embolic events in 93 elderly Chinese patients with atrial fibrillation.
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To evaluate the prevalence of embolic events and relevant factors in elderly Chinese patients with atrial fibrillation(AF), and to provide evidence on ways to prevent embolic events.</AbstractText>Autopsy data from ninety-three continous elderly Chinese patients with AF were analysed. The incidence of embolic events and its relationship to underlying disease, pathologic changes in the heart, and other clinical characteristics were examined.</AbstractText>Embolism were observed in 27 of 93 cases, with an incidence of 29.03%. The incidence of embolic events was higher in elderly patients with rheumatic heart disease than those with coronary artery disease, hypertensive myocardiopathy and heart diseases. Patients with chronic AF, with a course of AF > or = 3 years, and those with heart failure or diabetes had a higher incidence of embolic events than those without these complications. There was significant difference in incidence between paroxysmal and chronic AF. Patients with left atrial or ventricular enlargement, mural thrombosis in cardiac chambers, valvular calcification and valvular vegetation also had a higher incidence of embolic events. Oral dipyridamole (75-150 mg/d) or aspirin (50-150 mg/d) showed no definite effects in preventing embolism in some patients.</AbstractText>There was a high incidence of embolic events in elderly Chinese patients with AF. Anticoagulation therapy should be provided to the elderly patients with AF, especially to the patients with risk factors for embolism.</AbstractText>
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3,517
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Myocardial contraction bands. Definition, quantification and significance in forensic pathology.
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Pathological contraction bands affecting myocardial cells are observed in many different human conditions and in different experimental models. Their morphology was defined long ago but we need to understand the pathogenesis and functional meaning. A distinction between different histological forms of contraction bands and their quantification in a large spectrum of human diseases (262 cases) and a normal population sample where death was due to various types of accidental death (170 cases) produced the following conclusions: 1) The term "contraction band necrosis", as used presently, is ambiguous and should be reserved for a specific morpho-functional entity induced experimentally by intravenous catecholamine infusion and seen in equivalent human cases with pheochromocytoma. 2) In human pathology it may represent a sign of adrenergic stress linked with malignant arrhythmia/ventricular fibrillation. 3) Beyond a histological threshold of 37+/-7 foci and 322+/-99 myocells/100 mm2, the lesion may indicate sympathetic overdrive in the natural history of a disease and associated arrhythmogenic supersensitivity. 4) The detection of few pathological contraction bands in normal subjects in some types of accidental death correlates with the survival time, suggesting an agonal adrenergic stimulation to promote the cardiac pump.
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3,518
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[An autopsied case of marked cardiac hypertrophy due to multifactorial heart disease in an 85 year-old man who had been socially active].
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An autopsied 85-year-old man had suffered from a mild form of diabetes mellitus since the age of 67 and had experienced the first episode of heart failure with arapid ventricular rate of atrial fibrillation at the age of 72. He had remained socially active until he died suddenly of ventricular fibrillation, although he had complications of aortic regurgitation at the age of 76 and later mitral regurgitation at the age of 80. Chest roentgenograms showed gradual increase in the cardiothoratic ratio which reached 68.1% at the final stage. Autopsy revealedmarked left ventricular hypertrophy with a heart weight of 580 g, degeneration ofaortic valves, thickening of mitralvalve cusps and moderate coronary atherosclerosis without ischemic myocardial lesions. There were no specific lesions suggestive of primary cardiomyopathies on microscopic observations and the lesions of both aortic and mitral valves were not significant enough to explain the clinical findings of aortic and mitral regurgitation. Because the pathological examination failed to identify a single disease which was responsible for the marked cardiachypertrophy, we eventually reached the conclusion that the cardiac hypertrophy developed based on a multifactorial heart disease.
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3,519
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Clinical and electrophysiologic effects of calcium channel blockers in patients receiving ibutilide.
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Ibutilide is indicated for the acute termination of atrial fibrillation and atrial flutter. Recent work concludes that ibutilide activates a late inward sodium current that is blocked by nifedipine. Because calcium channel blockers are commonly used in patients with atrial fibrillation, it is important to exclude an antagonistic effect on ibutilide in the clinical setting.</AbstractText>We performed a retrospective electrocardiographic (ECG) review of patients enrolled in 3 clinical trials of ibutilide (2 atrial fibrillation conversion protocols and 1 ventricular tachycardia suppression protocol) to determine clinical efficacy and ECG effects of ibutilide in patients receiving and not receiving calcium channel blockers. Calcium channel blockers were administered as clinically indicated. A meta-analysis of the effects of calcium channel blockers on the conversion efficacy of atrial fibrillation and atrial flutter by ibutilide was also performed for studies in the literature.</AbstractText>One hundred thirty patients were included in the ECG analysis (106 from atrial fibrillation protocols and 24 from the ventricular tachycardia protocol). Sixty-eight of the 130 patients were taking calcium channel blockers at the time of ibutilide administration. There were no differences in the QT or QTc intervals, conversion rate for atrial fibrillation or atrial flutter, or suppression of ventricular tachycardia between patients taking and not taking calcium channel blockers. In the meta-analysis of 4 studies, there was no difference in the conversion rates between patients taking (52%, n = 221) and not taking (45%, n = 402) calcium channel blockers (P =.09).</AbstractText>In the clinical setting, the concomitant use of calcium channel blockers does not alter the ECG effects or efficacy of ibutilide for the treatment of atrial or ventricular arrhythmias.</AbstractText>
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3,520
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Clinical features and outcomes of elderly outpatients with heart failure followed up in hospital cardiology units: data from a large nationwide cardiology database (IN-CHF Registry).
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Congestive heart failure (HF) represents a major public health problem with an age-related increasing prevalence. Despite the high mortality and morbidity in elderly patients with HF, limited clinical and prognostic data are available for development of appropriate prevention and treatment strategies.</AbstractText>A cohort of 3327 outpatients consecutively enrolled in the Registry of Italian Network on Congestive Heart Failure by 133 cardiology centers was studied. Univariate and multivariate analyses were performed to compare patients <70 and > or =70 years old and to evaluate associations between clinical variables and the 1-year mortality rate and hospitalizations.</AbstractText>With respect to the 2294 patients <70 years old, the 1033 (31%) elderly patients were significantly more likely to be female, to be in New York Heart Association (NYHA) class III-IV, and to have preserved left ventricular systolic function (ejection fraction >40%), an ischemic/valvular etiology, and atrial fibrillation/flutter. Elderly patients received angiotensin-converting enzyme inhibitors, beta-blockers, and anticoagulants less frequently than younger patients did. The 1-year mortality rate was significantly higher in patients > or =70 years old (22% vs 13.7%, P <.001). Age was an independent predictor of 1-year mortality, increasing 2.8% by each year of age. Independent predictors of 1-year mortality in elderly patients were (1) > or =1 hospital admission in the previous year (relative risk [RR] 2.09, 95% CI 1.51-2.87), (2) systolic blood pressure (RR 0.98, 95% CI 0.97-0.99), (3) NYHA class III-IV (RR 1.57, 95% CI 1.20-2.07), and (4) age (RR 1.028, 95% CI 1.001-1.056).</AbstractText>Our study confirms that elderly patients (1) are seen in a more advanced stage of HF, (2) are less likely to receive evidence-based treatments, (3) show more frequently preserved systolic function, and (4) have a worse prognosis. Consequently, there is a need to develop more effective and targeted management strategies for this escalating health problem.</AbstractText>
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3,521
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Use of an inspiratory impedance valve improves neurologically intact survival in a porcine model of ventricular fibrillation.
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This study evaluated the potential for an inspiratory impedance threshold valve (ITV) to improve 24-hour survival and neurological function in a pig model of cardiac arrest.</AbstractText>Using a randomized, prospective, and blinded design, we compared the effects of a sham versus active ITV on 24-hour survival and neurological function. After 6 minutes of ventricular fibrillation (VF), followed by 6 minutes of cardiopulmonary resuscitation (CPR) with either a sham or an active valve, anesthetized pigs received 3 sequential 200-J shocks. If VF persisted, they received epinephrine (0.045 mg/kg), 90 seconds of CPR, and 3 more 200-J shocks. A total of 11 of 20 pigs (55%) in the sham versus 17 of 20 (85%) in the active valve group survived for 24 hours (P<0.05). Neurological scores were significantly higher with the active valve; the cerebral performance score (1=normal, 5=brain death) was 2.2+/-0.2 with the sham ITV versus 1.4+/-0.2 with the active valve (P<0.05). A total of 1 of 11 in the sham versus 12 of 17 in the active valve group had completely normal neurological function (P<0.05). Peak end-tidal CO2 (PETCO2) values were significantly higher with the active valve (20.4+/-1.0) than the sham (16.8+/-1.5) (P<0.05). PETCO2 >18 mm Hg correlated with increased survival (P<0.05).</AbstractText>Use of a functional ITV during standard CPR significantly improved 24-hour survival rates and neurological recovery. PETCO2 and systolic blood pressure were also significantly higher in the active valve group. These data support further evaluation of ITV during standard CPR.</AbstractText>
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3,522
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Clinical and echocardiographic characteristics of patients with left atrial thrombus and sinus rhythm: experience in 20 643 consecutive transesophageal echocardiographic examinations.
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Left atrial (LA) thrombus is infrequently detected in the presence of sinus rhythm (SR) and, in these cases, is usually associated with additional cardiac pathologies. We sought to determine the clinical and echocardiographic characteristics of patients with LA thrombus and SR to define a high-risk group of patients prone to this uncommon clinical presentation.</AbstractText>The institution's echocardiographic laboratory database was searched to identify patients with LA thrombus, diagnosed by transesophageal echocardiography (TEE), who were in SR during the TEE examination. Of 20 643 consecutive TEE examinations performed during an 11-year period, LA thrombus was detected in 314 patients in 380 TEE examinations. Of these, SR was present in 20 patients (age 69+/-13 years; 40% men) in 23 examinations (0.1% of all TEE examinations; 6.1% of TEE examinations with LA thrombus). High-risk structural heart disease (severe left ventricular dysfunction or significant left-sided valve disease [predominantly mitral valve disease]), previous documented episodes of atrial fibrillation, or both (structural heart disease and previous atrial fibrillation) were present in 10, 4, and 5 of the 20 patients, respectively. Only 1 patient with LA thrombus and SR did not have high-risk features.</AbstractText>LA thrombus is very infrequently detected in the presence of SR. Patients with LA thrombus and SR constitute a high-risk group characterized by specific structural cardiac abnormalities or previous atrial fibrillation, abnormalities that are potentially detectable before TEE.</AbstractText>
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3,523
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r-hirudin as anticoagulant for cardiopulmonary bypass.
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A 68-year-old woman with unstable angina and an episode of ventricular fibrillation developed a persistent and recurrent rash due to heparin. Medical therapy was continued with danaproid. For cardiopulmonary bypass and coronary artery grafting, r-hirudin was used as the anticoagulant. There were no thrombotic or coagulopathic complications. There is still no ideal alternative to unfractionated heparin for anticoagulation for cardiopulmonary bypass. The use of r-hirudin was successful and we describe our anticoagulant strategy.
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3,524
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Outcome of cardiac arrests in a Portuguese hospital--evaluation of a hospital cardiopulmonar resuscitation program at one year.
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Evaluation of a hospital-wide resuscitation program at one year.</AbstractText>All records of cardiac arrest calls were collected, logged in a database by the same operator, and analyzed. The cardiac arrest teams consist of a physician and a nurse with ALS (Advanced Life Support) training. Each team has a radio that is activated by a single emergency number. Only cardiac arrest calls were analyzed.</AbstractText>Between March 1999 and March 2000 there were 173 emergency team calls. Of these, 120 were cardiac arrest calls (90 in-hospital and 30 from the emergency room--out-of-hospital cardiac arrests). Of the 90 in-hospital cardiac arrests, 61% were male, and median age was 73 years. In 90% of the calls, basic life support (BLS) was started before the arrival of the cardiac arrest team. The immediate cause was cardiac in 39% of the patients. Initial rhythm was ventricular fibrillation in 8%, asystole in 60% and other rhythms in 24% of the patients. Thirty percent presented return of spontaneous circulation (ROSC). There were no differences between those in whom BLS was started before the arrival of the cardiac arrest team and those in whom BLS had not been started. Ten patients (11%) were discharged from hospital. Of the 30 out-of-hospital cardiac arrests, 70% were male, and median age was 69 years. In 97% BLS was started before the arrival of the cardiac arrest team. The immediate cause was cardiac in 30% of patients. Initial rhythm was ventricular fibrillation in 10%, asystole in 73% and other rhythms in 17% of the patients. ROSC was achieved in 27% of the patients. Three patients (10%) were discharged from hospital. There were no differences either in ROSC or in survival to hospital discharge between in-hospital and out-of-hospital cardiac arrests. The state of health previous to cardiac arrest was significantly different between in- and out-of-hospital cardiac arrests: 3% versus 32% healthy, with no functional limitation. The authors conclude that: first, the current records do not enable all the desired goals of the "Utstein style" to be achieved and need to be reviewed; second, 90 to 97% of BLS previous to the arrival of the cardiac arrest team is a good indication of the efficiency of the hospital-wide program, which included training in BLS for all the hospital staff; third, the survival rate, although in accordance with much of the literature, could be improved.</AbstractText>
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3,525
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[Results of coronary artery bypass grafting in patients with impaired left ventricular systolic function].
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The purpose of this study was to examine the early and late results of CABG in patients with left ventricular ejection fraction (LVEF) lower than 40%. This study comprised 128 patients (114 male and 14 female) at age from 41 to 75 years (mean 58.3 +/- 7.9). Before operation 115 patients (89.8%) were in CCS class III or IV. Before operation in all patients coronary arteriography with left-sided ventriculography were performed. In 12 patients myocardial perfusion in SPECT with Tc-99m-MIBI was assessed. Perioperative mortality in whole group was 12.5% (16 patients). The lowest (9.2%) was in subgroup with LVEF from 0.31 to 0.4 and the highest (27.3%) in patients with LVEF below 0.2. In 8 patients death was caused by low cardiac output, in 4 by ventricular fibrillation, in the others by renal failure or cerebral stroke (2 patients in each). In 45 patients (35.2%) postoperative low cardiac output was observed. In 41 patients was treated with the use of intraaortic balloon pumping (IABP). Twenty seven (65.9%) patients with IABP survived. During follow-up died 5 pts. 24-months probability of survival calculated from Kaplan-Meier method was 82.4%. In follow-up 80.9% of patients were in CCS class I and II. In SPECT, four months after CABG significantly more segments of left ventricle with normal perfusion (45% vs 53%; p < 0.05) were observed. Patients with LVEF < 40% are at higher operative risk because of often postoperative low output syndrome. Low output syndrome can by successfully treated with IABP. CABG significantly improves circulatory sufficiency in patients with LVEF < 40%.
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3,526
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[Endothelin-1 in coronary artery disease].
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Endothelins (ETs) are the peptides made up of 21 amino acids synthesized and released by variety of cells. Following studies revealed three isoforms of ETs-ET-1, ET-2 and ET-3. Endothelin ET-1 is known as the most potent endothelium-derived vasoconstrictor peptide identified so far. Endothelin ET-1 acts in a paracrine manner on the two types of receptors ET-A and ET-B. The former is responsible for the vascular smooth muscle constriction and the latter for vasodilation or vasoconstriction depending on the subtype of this receptor (ET-B1 or ET-B2 respectively). Endothelin receptor subtypes have been demonstrated and pharmacologically characterized in the coronary vascular bed. A good deal of experimental and clinical data has been accumulated to support an important role of endothelin-1 in ischemic heart disease. In experimental animals, exogenous ET-1 was found to cause coronary vasoconstriction and, at higher doses, ventricular fibrillation and death. The plasma levels of immunoreactive endothelin-1 were found to be increased in patients with coronary arteriosclerosis, acute myocardial infarction, and angina. The purpose of this study was to critically review the experimental and clinical data supporting the involvement of ET-1 in ischemic heart disease.
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3,527
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Right ventricular electrocardiographic leads for detection of Brugada syndrome in sudden unexplained death syndrome survivors and their relatives.
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Sudden unexplained death syndrome (SUDS) is a sudden death syndrome in previously healthy Southeast Asian young adults without any structural causes of death. Many SUDS survivors show electrocardiographic (ECG) evidence of RSR' and ST elevation in leads V1 to V3, which is similar to the ECG pattern in Brugada syndrome. However, in many cases transient normalization of the ECG does not make diagnosis with standard 12-lead ECG possible.</AbstractText>To overcome this problem, we utilized the new right ventricular ECG leads to detect the Brugada syndrome in SUDS survivors.</AbstractText>The subject was a Thai male patient who presented with a SUDS-like syncopal attack. He had cardiac arrest due to idiopathic ventricular fibrillation.</AbstractText>Post-resuscitation standard 12-lead ECG showed no diagnostic features of Brugada syndrome. However, ECG patterns of RSR' and ST elevations typical for Brugada syndrome could be detected at the higher intercostal space leads V1 to V3. We observed similar findings in 2 of the other 10 SUDS survivors and 4 of 23 healthy family members.</AbstractText>Our data suggest that these new right ventricular leads ECG may be helpful in detecting Brugada syndrome in SUDS survivors and their relatives.</AbstractText>
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3,528
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Clinical characteristics of rapid atrial fibrillation preceding ventricular tachycardia.
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Spontaneous degeneration of rapid atrial fibrillation (AF) to ventricular fibrillation has been documented in patients with hypertrophic cardiomyopathy (HCM) and Wolff-Parkinson-White (WPW) syndrome. However, the importance of rap
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3,529
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[Chronic hepatitis ascribed to the use of sotalol].
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In a 68-year-old woman with severe chronic hepatitis an extensive investigation revealed no other cause than the use of sotalol for 10 months due to atrial fibrillation. Once the use of the medication had been discontinued the patient's symptoms quickly disappeared and the liver function disorders normalised within 5 months. Sotalol is a beta-adrenergic receptor blocking and anti-arrhythmic agent. It is widely used in patients with supraventricular and ventricular arrhythmias. An adverse effect in terms of liver damage is not known. The pathogenesis of the observed hepatitis remained an enigma because sotalol is a hydrophilic substance which is not metabolized by the liver and is cleared by the kidneys unchanged.
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3,530
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Magnesium efficacy in magnesium deficient and nondeficient patients with rapid ventricular response atrial fibrillation.
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We assessed the effect of magnesium sulphate (MgSO4) on lowering the rate in ventricular atrial fibrillation (AF), and evaluated the effect of this therapy in magnesium (Mg) deficient and nondeficient patients. This experimental clinical study was performed on 34 patients with rapid AF (ventricular rate [VR] > 120/minute) presenting to the emergency department of a tertiary care university hospital. Patients with systolic blood pressure < or = 100 mmHg, Hb level < or = 11.8, saO2 of < or = 96%, BUN > or = 40 or creatine > or = 1.8 were excluded (n = 15). Nineteen patients were given an initial 2 g MgSO4 bolus i.v. and a 1 g/hour continuous infusion over 6 hours. To evaluate the presence of Mg deficiency, urine was collected from the onset of treatment and continued for the next 24 hours, and the excretion rate of administered Mg was calculated. Ventricular rates were obtained at baseline, after MgSO4 bolus, and every 15 minutes for the first hour. The decrease in the VR was statistically significant at 15, 30 and 60 minutes after Mg therapy (p = 0.0025, p < 0.001, p > 0.001). There was no difference in the response to Mg therapy between Mg deficient and nondeficient patients at 15, 30 or 60 minutes after therapy (p = 0.41, p = 0.28, p = 0.08). It is concluded that i.v. MgSO4 has a statistically significant but clinically limited effect on VR and this effect did not differ between patients with and without Mg deficiency.
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3,531
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[Diffusion-weighted imaging of brain death: study of apparent diffusion coefficient].
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DWI(Diffusion-weighted images) of the brain has been revealed to be useful in diagnosis of several clinical conditions. However, little is known about DWI with regard to brain death. We had opportunities to study patients with brain death. Case 1. A 34-year-old woman experienced cardiopulmonary arrest due to severe ventricular fibrillation, and resuscitated after about 120 minutes. After brain death, DWI showed high signals in the cerebral cortex, putamen, thalamus, brain stem and cerebellum, and ADC(apparent diffusion coefficient) values were 30-40% lower than those of normal volunteers. Case 2. A 45-year-old woman experienced cardiopulmonary arrest due to pontine hemorrhage, and was resuscitated after about 20 minutes. Before brain death, DWI showed high signals in the cerebral cortex, putamen, thalamus, brain stem and cerebellum, and ADC values were the same as those of normal volunteers. After brain death, DWI showed more clearly defined in these areas, but ADC values were 30-40% lower than the first values. DWI and ADC mapping shows areas corresponding to edema of a cytotoxic nature and to ischemic tissue. The characteristic views of high signals in the whole area of the brain were present, and an objective evaluation was possible with DWI after the brain death diagnosis by measuring ADC values.
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3,532
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Localization of the origin of arrhythmias for ablation: from Electrocardiography to advanced endocardial mapping systems.
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Radiofrequency catheter ablation techniques have had a dramatic impact on the treatment of a variety of cardiac arrhythmias. However, catheter ablation of complex arrhythmias, such as intra-atrial reentry, ventricular tachycardias, and atrial fibrillation, continues to pose a major challenge. This stems from limitations of fluoroscopy and conventional catheter-based mapping techniques that limit the accurate anatomic localization of complex arrhythmogenic substrates. In this article, ECG features of complex arrhythmias are reviewed, which may facilitate the planning of an ablation procedure. The physical principles of the newly available catheter-based endocardial mapping techniques and their clinical applicability for treatment of complex arrhythmias are discussed. The role of intracardiac echocardiography to facilitate mapping and ablation is reviewed.
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3,533
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In vivo electrophysiologic studies in endothelial nitric oxide synthase (eNOS)-deficient mice.
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Endothelial nitric oxide synthase (eNOS) mediates attenuation of the L-type calcium channel and modulates myocyte contractility. Arrhythmogenic afterdepolarizations are seen in vitro in ouabain-treated isolated myocytes from eNOS-deficient mice. The aim of these studies was to characterize the baseline electrophysiologic (EP) phenotype of eNOS-deficient mice and their potential susceptibility to cardiac conduction abnormalities and inducible arrhythmias.</AbstractText>Surface ECG and in vivo intracardiac EP studies were performed in 27 mice lacking the eNOS gene and 21 wild-type littermate control mice. Baseline studies were performed in 10 eNOS-deficient mice and 10 wild-type controls. Subsequently, 17 eNOS-deficient mice and 11 wild-type controls were pretreated with digoxin, and ECG and EP testing were repeated. Data analysis revealed no significant differences in ECG intervals or cardiac conduction parameters, except sinus cycle length was higher in eNOS-deficient mice than wild-type mice (P < 0.01). After digoxin pretreatment, 7 of 17 eNOS-deficient mice had inducible ventricular tachycardia and 2 others had frequent ventricular premature beats, compared with only 3 of 11 wild-type mice with inducible ventricular tachycardia. In addition, 2 digoxin-treated eNOS-deficient mice and 1 wild-type mouse had inducible nonsustained atrial fibrillation.</AbstractText>Mice with a homozygous targeted disruption of the eNOS gene have slower heart rates but no other distinguishable EP characteristics under basal sedated conditions. Partial inhibition of the Na+/K+ ATPase pump with digoxin administration increases ventricular ectopic activity in eNOS-/- mice, a phenotype analogous to afterdepolarizations seen in vitro in this eNOS-deficient mouse model.</AbstractText>
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3,534
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Clinical experience with a dual-chamber implantable cardioverter defibrillator to treat atrial tachyarrhythmias.
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This study evaluated the safety and efficacy of a new dual-chamber implantable cardioverter defibrillator (ICD) to detect and treat atrial tachyarrhythmias in patients with drug-refractory atrial fibrillation (AF) and no indication for a ventricular ICD.</AbstractText>A dual-chamber ICD (Medtronic 7250 Jewel AF) was implanted in 144 of 146 patients. The device discriminates atrial tachycardia from AF based on cycle length and regularity, and uses atrial overdrive pacing as well as shocks to terminate tachyarrhythmia episodes. Patients were followed for an average of 12.6+/-6.2 months. Use of antiarrhythmic drugs was 63% at baseline and did not change over time. Kaplan-Meier estimates of 12-month complication-free survival, device therapy survival, and patient survival were 85%, 91%, and 98%, respectively. Positive predictive accuracy of spontaneous atrial tachyarrhythmia detection was 99%, while atrial overdrive pacing and shocks terminated 40% and 87% of treated episodes, respectively. Median duration of successfully treated episodes was 8.9 minutes versus 144 minutes for the therapy failures. There was no reduction in the use of patient-activated shock therapy over time; at the 12-month follow-up evaluation, 94% of patients were in sinus rhythm. Ventricular tachyarrhythmias (67 episodes) were detected and appropriately treated in 7.6% of patients.</AbstractText>This dual-chamber ICD appears to be safe and well tolerated in patients with drug-refractory symptomatic atrial tachyarrhythmias. The device, used in combination with drugs, effectively treats atrial tachyarrhythmias with pacing and/or shock therapies and decreases the median episode duration. In addition, the device protects from ventricular tachyarrhythmias in patients with AF and structural heart disease.</AbstractText>
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3,535
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[Pacing mode influence on morbidity and mortality].
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It is widely believed that physiologic pacing (defined as atrial or atrioventricular synchronous pacing) reduces cardiac morbidity and mortality and is associated with improved quality of life compared to ventricular pacing. In this review we present data from three large prospective trials (PASE, CTOPP, MOST) comparing physiologic pacing to ventricular pacing. The prospective trials report that physiologic pacing is associated with a reduced risk of developing chronic atrial fibrillation over time and improved quality of life in patients with sinus node disease compared to ventricular pacing. However, these trials failed to demonstrate that physiologic pacing reduces heart failure, thromboembolism, or cardiac death compared to ventricular pacing. Based on the available clinical trials, physiologic pacing is not indicated in patients with a short life expectancy. Physiologic pacing should be considered for younger patients (age < 75 years), patients likely to be pacemaker dependent, and patients for whom maintenance of sinus rhythm is desirable, i.e., patients with ventricular hypertrophy and diastolic dysfunction who are most likely to be severely symptomatic if AV synchrony is lost.
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3,536
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[Severe accidental hypothermia in an elderly woman].
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Profound hypothermia (core temperature of less than 28 degrees C) is a life threatening state and a medical emergency associated with a high mortality rate. The prognosis depends on underlying diseases, advanced or very early age, the duration prior to treatment, the degree of hemodynamic deterioration, and especially, the methods of treatment, including active external or internal rewarming. This is a case study of an 80-year-old female patient with severe accidental hypothermia (core temperature 27 degrees C). She was found in her home lying immobile on the cold floor after a fall. The patient was in a profound coma with cardiocirculatory collapse, and the medical staff treating her was inclined to pronounce her deceased. On her arrival at the hospital, she was resuscitated, put on a respirator and actively warmed. Very severe metabolic disorders were found, including a marked metabolic acidosis composed of diabetic ketoacidosis (she had suffered from insulin treated type 2 diabetes mellitus) and lactic acidosis with a very high anion gap (42) and a hyperosmotic state (blood glucose 1202 mg/dl). There were pathognomonic electrocardiographic abnormalities, J-wave of Osborn and prolonged repolarization. Slow atrial fibrillation with a ventricular response of 30 bpm followed by a nodal rhythm of 12 bpm and reversible cardiac arrest were recorded. The pulse and blood pressure were unobtainable. Despite the successful resuscitation and hemodynamic and cognitive improvement, rhabdomyolysis (CKP 6580 u/L), renal failure and hepatic damage developed. She was extubated and treated with intravenous fluids containing dopamine, bicarbonate, insulin and antibiotics. Her medical condition gradually improved, and she was discharged clear minded, functioning very well and independent. Renal and liver tests returned eventually to normal limits. Progressive bradycardia, hypotension and death due to ventricular fibrillation or asystole commonly occur during severe hypothermia. Respiratory and metabolic, sometimes lactic, acidosis, lethargy and coma, hypercoagulopathy, hyperosmolar state, acute pancreatitis and renal and hepatic failure are frequent complications of hypothermia. Underlying predisposing causes of hypothermia are diabetic ketoacidosis, cerebrovascular disease, mental retardation, hypothyroidism, pituitary and adrenal insufficiency, malnutrition, acute alcoholism, liver damage, hypoglycemia, sepsis, hypothalamic dysfunction, sepsis and polypharmacy, and especially, the use of sedative and narcotic drugs. Our case demonstrates once again that CPR once begun should continue until the successful rewarming because "no one is dead until warm and dead".
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3,537
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Relative safety of mirtazapine overdose.
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A 43-y-o male with a history of AIDS, atrial fibrillation, and alcohol abuse presented to the emergency department 2 h after ingestion of 25 tablets of 15 mg mirtazapine (total 375 mg) with ethanol in a suicide attempt (no other coingestion). Vital signs were normal except for a mild tachycardia (rate 112). Physical examination was unremarkable except for lethargy. Fifty grams of activated charcoal with sorbitol was given. Electrocardiogram showed sinus tachycardia, left ventricular hypertrophy, and non-specific ST-segment changes. Serum mirtazapine on admission was 530 ng/mL (therapeutic level 20-50 ng/mL). Overnight monitoring revealed no tachyarrythmias, and discharge occurred after psychiatric evaluation. It appears that ingestions of mirtazapine approximately 10-fold of therapeutic exhibit minimal acute toxicity. From this and other cases in the literature exhibiting a 10-fold overdose, we conclude that isolated mirtazapine ingestions of this magnitude require no acute intervention other than short term (about 6 h) observation.
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3,538
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Does the progression of myocardial fibrosis lead to atrial fibrillation in patients with hypertrophic cardiomyopathy?
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The majority of left ventricular (LV) inflow volumes in hypertrophic cardiomyopathy (HCM) depend on atrial contraction because of impaired LV relaxation. If HCM is complicated by atrial fibrillation (AF), heart failure can develop because of the loss of atrial contraction. The purpose of this study was to determine the relationship between the development of AF and myocardial fibrosis or intramyocardial small artery (IMSA) stenosis in autopsied hearts with HCM. Studies were performed in five HCM hearts with AF (AF group) and five HCM hearts without AF (non-AF group). LV specimens were divided into the inner (IT), middle (MT), and outer (OT) thirds. We selected at random 120 fields and 20 IMSAs from each layer and assessed them quantitatively using an image analyzer. We determined the extent of fibrosis (%F) and the degree of stenosis of each IMSA (%L). The %F in the AF group was greater than in the non-AF group (P<.01). In the AF group, the %F of the IT was greater than in the MT and the OT (P<.01). In the non-AF group, the %F of the IT was greater than in the MT (P<.05), and the %F of the MT was greater than in the OT (P<.01). The %L was similar in the AF and non-AF groups. In both groups, the %L of the IT was lower than in the MT (P<.01), which was lower than that of the OT (P<.05). LV fibrosis is more severe in patients with HCM and AF than in those without AF. Therefore, myocardial fibrosis might impair LV relaxation, resulting in hemodynamic intolerance to AF.
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3,539
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Molecular genetic basis of sudden cardiac death.
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In this review, the up-to-date understanding of the molecular basis of disorders causing sudden death will be described. Two arrhythmic disorders causing sudden death have recently been well described at the molecular level, the long QT syndromes (LQTS) and Brugada syndrome, and in this article we will review the current scientific knowledge of each disease. A third disorder, hypertrophic cardiomyopathy (HCM), a myocardial disorder causing sudden death, has also been well studied. Finally, a disorder in which both myocardial abnormalities and rhythm abnormalities coexist, arrhythmogenic right ventricular dysplasia (ARVD) will also be described. The role of the pathologist in these studies will be highlighted.
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3,540
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Endocardial wave front organization during ventricular fibrillation in humans.
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This study was designed to characterize the organization of ventricular fibrillation (VF) on the endocardium of humans.</AbstractText>Most proposed mechanisms for the maintenance of VF postulate the propagation of a number of activation wave fronts that reenter to maintain the arrhythmia. We tested the hypothesis that, in patients undergoing internal cardioverter-defibrillator implantation, VF consists primarily of a few large wave fronts on the endocardium.</AbstractText>Electrograms were recorded from a 36-electrode catheter in the left ventricle of 16 patients during VF. Activation times were chosen for a 2-s epoch for each fibrillation episode, and a two-dimensional Kolmogorov-Smirnov test was performed to determine if activation occurred randomly along the catheter over that time interval. The maximum cross-correlation was found for all possible pairs of electrodes on the catheter, and these values were plotted relative to the distance between the two electrodes. An exponential curve was then fit to the data, and a length constant was determined. Activation times were grouped into wave fronts along the catheter, and the lengths of the wave fronts were estimated.</AbstractText>The Kolmogorov-Smirnov test showed that activation was not random along the catheter in any of the patients studied. The correlation length determined was 9 +/- 2 cm. The number of wave fronts recorded by the catheter was 9.2 +/- 2.9 wave fronts/s. The length of the pathway of each wave front along the catheter was 6.5 +/- 4.5 cm.</AbstractText>Ventricular fibrillation is well organized on the endocardial surface of humans, consisting primarily of a few large wave fronts on the order of 6 to 9 cm.</AbstractText>
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3,541
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[Permanent pacing of the bundle of His after radiofrequency atrioventricular node ablation in patients with suprahisian conduction disturbances].
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The asynchronic contraction of the left ventricle due to left bundle branch block or right ventricular pacing is inferior from a hemodynamic point of view to the synchronic contraction through the conduction system. Several authors have reported some cases of pump failure and deterioration of mitral regurgitation after AV nodal ablation. Alternative sites of pacing such as the right ventricular outflow tract pacing have been proposed in order to avoid these complications. Direct His bundle pacing might be a new alternative for permanent pacing, however, it has not been extensively evaluated in humans yet. Our aim is to prove the feasibility of permanent His pacing in terms of stability, thresholds and pump function.</AbstractText>patients without structural heart disease, selected for AV nodal ablation due to uncontrolled paroxysmal atrial fibrillation, or for pacemaker implantation due to supraHis conduction disturbance, with normal conduction system. An active fixation permanent lead was placed in His position using an steering guidewire and a diagnostic catheter as an anatomical reference. We also implanted a lead in the right atrial appendage and both were connected to a DDDR generator. Pacing thresholds and ecocardiographic ventricular function parameters were evaluated (ejection fraction, cavity size, mitral regurgitation).</AbstractText>12 patients met the inclusion criteria. Successful His pacing was achieved in 8 out of 12 cases (66%) with acceptable thresholds at implantation (1.24 +/- 0.13 volts at 0.5 ms) and during follow up at 3 months (1.31 +/- 0.20 volts at 0.5 ms). Neither a significant change in the ecocardiographic parameters not a deterioration in the clinical status caused by ablation or stimulation was evidenced.</AbstractText>The His bundle may be the site of choice for long term pacing in patients with AV block and normal infraHis conduction system.</AbstractText>
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3,542
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Sevoflurane before or after ischemia improves contractile and metabolic function while reducing myoplasmic Ca(2+) loading in intact hearts.
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Ca(2+) loading occurs during myocardial reperfusion injury. Volatile anesthetics can reduce reperfusion injury. The authors tested whether sevoflurane administered before index ischemia in isolated hearts reduces myoplasmic diastolic and systolic [Ca(2+)] and improves function more so than when sevoflurane is administered on reperfusion.</AbstractText>Four groups of guinea pig hearts were perfused with crystalloid solution (55 mmHg, 37 degrees C): (1) no treatment before 30 min global ischemia and 60 min reperfusion (CON); (2) 3.5 vol% sevoflurane administered for 10 min before ischemia (SBI); (3) 3.5 vol% sevoflurane administered for 10 min after ischemia (SAI); and (4) 3.5 vol% sevoflurane administered for 10 min before and after ischemia (SBAI). Phasic myoplasmic diastolic and systolic [Ca(2+)] were measured in the left ventricular free wall with the fluorescence probe indo-1.</AbstractText>Ischemia increased diastolic [Ca(2+)] and diastolic left ventricular pressure (LVP). In CON hearts, initial reperfusion greatly increased diastolic [Ca2+] and systolic [Ca(2+)] and reduced contractility (systolic-diastolic LVP, dLVP/dt(max)), relaxation (diastolic LVP, dLVP/dt(min)), myocardial oxygen consumption (MvO(2)), and cardiac efficiency. SBI, SAI, and SBAI each reduced ventricular fibrillation, attenuated increases in systolic and systolic-diastolic [Ca(2+)], improved contractile and relaxation indices, and increased coronary flow, percent oxygen extraction, MvO(2), and cardiac efficiency during 60 min reperfusion compared with CON. SBI was more protective than SAI, and SBAI was generally more protective than SAI.</AbstractText>Sevoflurane improves postischemic cardiac function while reducing Ca(2+) loading when it is administered before or after ischemia, but protection is better when it is administered before ischemia. Reduced Ca(2+) loading on reperfusion is likely a result of the anesthetic protective effect.</AbstractText>
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3,543
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Radiofrequency ablation in pediatric and adult patients: comparative results.
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Radiofrequency (RF) catheter ablation has been widely and successfully employed to cure adult and pediatric patients of a variety of arrhythmias. Only limited data exist which compare the results in these two groups. The aim of this study was to compare the efficacy and safety of RF catheter ablation in pediatric versus adult patients performed by an adult electrophysiology (EP) team.</AbstractText>The study group included 327 consecutive pediatric (n=47) and adult (n=280) patients, aged 7-82 years (mean 40+/-19), with symptomatic tachyarrhythmias, who underwent RF ablation during the last 6 years. All but ten patients underwent a full EP study during the same session. Procedures were performed in all but five patients with use of local anesthesia and deep or light sedation. The left heart was approached with use of transaortic (n=36) or transseptal (n=55) or both (n=6) techniques. RF ablation was performed for manifest or concealed accessory pathways in 132 patients, AV nodal slow pathway in 119, atrial tachycardia in 24, atrial flutter in 15, atrial fibrillation in one, ventricular tachycardia in 29, and AV node/His bundle in 7 patients.</AbstractText>RF ablation was successful in 271 (96.8%) patients in the adult group and in all patients (100%) in the pediatric group, with a mean of 15+/-18 (median: 8) vs 12+/-10 (median: 8) RF applications respectively (P=NS). Complications occurred in four patients (1.4%) in the adult group and in one patient (2.1%) in the pediatric group (P=NS). Fluoroscopy time averaged 43+/-40 min vs 39+/-27 min and procedures lasted for 3.0+/-1.9 hours vs 2.8+/-1.4 hours respectively (P=NS). During long-term follow-up of 25+/-19 months, there were 12 (4.4%) recurrences among the adult patients, and three (6.4%) recurrences in children, with nine of them successfully treated with repeat RF ablation. Procedural variables were dependent on the type of arrhythmia ablated, rather than on patient's age. Patients with multiple accessory pathways or atrial flutter required the greatest number of RF applications and the longest fluoroscopy exposure and duration of the procedure; the lowest values of these variables concerned ablation of the slow AV nodal pathway or the AV node/His bundle.</AbstractText>RF ablation in adult and pediatric patients performed by an adult EP team is equally efficacious and safe offering cure of symptomatic cardiac tachyarrhythmias in both patient populations.</AbstractText>
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3,544
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Single-agent pegylated liposomal doxorubicin (Caelix) in chemotherapy pretreated non-small cell lung cancer patients: a pilot trial.
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Polyethylene glycol-coated (pegylated) liposomal doxorubicin (PLD) is a new formulation of doxorubicin with peculiar pharmacokinetic and pharmacodinamic properties, a favorable toxic profile and a demonstrated activity in solid tumors. We tested PLD in locally advanced or metastatic NSCLC patients, progressed after a platinum-based first-line chemotherapy. PLD was administered at the dose of 35 mg/m(2) every 21 days. After the first six patients had been accrued, due to the low toxicity shown in the first six patients, the dose was escalated to 45 mg/m(2). Seventeen patients were enrolled in the study and were considered eligible for evaluation of toxicity and response. Stomatitis, palmar-plantar erythrodysaesthesia (PPE) and asthenia were the most common toxicities and affected approximately half of the treated patients. Stomatitis occurred in 8/17 patients and was grade 3-4 in three. PPE was seen in 9/17 and was grade 3 in one. In the group treated at the dose of 45 mg/m(2) PPE was more frequent and severe and required treatment delay in some cases. Other toxicities were equally distributed among the two groups. Hematological toxicity was not common and never reached grade 3-4. However, one patient with grade 2 leucopenia had pneumonia and died. Clinically evident heart failure was never recorded. Left ventricular ejection fraction was assessed in three patients after PLD treatment (in one case after the first course, due to the occurrence of atrial fibrillation, and in two cases after six courses) and was unchanged compared to pre-treatment assessment. One confirmed partial response was observed (5.8%); five patients (29.4%) had stable disease (including one minor response) and nine (52.9%) had disease progression. Median time to progression was 9.5 weeks, median survival 18.6 weeks. PLD at the doses employed in this study can be safely administered and has shown activity in platinum pretreated NSCLC patients.
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3,545
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Novel PRKAG2 mutation responsible for the genetic syndrome of ventricular preexcitation and conduction system disease with childhood onset and absence of cardiac hypertrophy.
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We recently reported a mutation in the PRKAG2 gene to be responsible for a familial syndrome of ventricular preexcitation, atrial fibrillation, conduction defects, and cardiac hypertrophy. We now report a novel mutation in PRKAG2 causing Wolff-Parkinson-White syndrome and conduction system disease with onset in childhood and the absence of cardiac hypertrophy.</AbstractText>DNA was extracted from white blood cells obtained from family members. PRKAG2 exons were amplified by polymerase chain reaction and were screened for mutations by direct sequencing. The genomic organization of the PRKAG2 gene was determined using inter-exon long-range polymerase chain reaction for cDNA sequence not available in the genome database. A missense mutation, Arg531Gly, was identified in all affected individuals but was absent in 150 unrelated individuals. The PRKAG2 gene was determined to consist of 16 exons and is at least 280 kb in size.</AbstractText>We identified a novel mutation (Arg531Gly) in the gamma-2 regulatory subunit (PRKAG2) of AMP-activated protein kinase (AMPK) to be responsible for a syndrome associated with ventricular preexcitation and early onset of atrial fibrillation and conduction disease. These observations confirm an important functional role of AMPK in the regulation of ion channels specific to cardiac tissue. The identification of the cardiac ion channel(s) serving as substrate for AMPK not only would provide insight into the molecular basis of atrial fibrillation and heart block but also may suggest targets for the development of more specific therapy for these common rhythm disturbances.</AbstractText>
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3,546
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Regional prolongation of ARI and altered restitution properties cause ventricular arrhythmia in heart failure.
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The mechanism of arrhythmogenicity in heart failure remains poorly understood. We examined the relationship between electrical abnormalities and ventricular arrhythmia by using experimental heart failure models. Sixty unipolar electrograms were recorded from the entire cardiac surface in control dogs (n = 13) and pacing-induced heart failure dogs (n = 16). In failing hearts, activation time (AT) was delayed at the apex, and AT dispersion increased in failing hearts. Activation-recovery intervals (ARI) were prolonged mainly at the apex and ARI dispersion was significantly augmented. The slope of the ARI restitution curve, interaction of diastolic interval, and ARI in failing hearts was significantly steeper than in control hearts. Ventricular fibrillation (VF) was easily induced by programmed stimulation in failing hearts, whereas no arrhythmia occurred in control hearts. Computer simulation studies could reproduce the experimental results. Altering the ARI restitution to the steep slope causes VF in a model heart. It is suggested that electrical remodeling, especially steepness of electrical restitution, may play a role in arrhythmogenicity in failing hearts.
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3,547
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Paroxysmal atrial fibrillation.
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There has been a tendency to treat paroxysmal atrial fibrillation (PAF) in a similar way to sustained AF, but treatment objectives may be very different. We discuss current definitions, epidemiology, pathophysiology and natural history of PAF, and review evidence for its treatment and management. PAF comprises between 25% and 62% of cases of AF, with similar underlying causes to those in sustained AF. The main objective of management is prevention of paroxysms and long-term maintenance of sinus rhythm, and Class 1c drugs are highly effective, although beta-blockers are useful alternatives. If patients have severe coronary artery disease or poor ventricular function, amiodarone is probably the drug of choice. Although randomized controlled trials of thromboprophylaxis in patients with paroxysmal AF per se are lacking, the approach to patients with paroxysmal AF should be similar to that in patients with sustained AF, with warfarin for 'high risk' patients and aspirin for those at 'low risk'. Non-pharmacological therapeutic options, including pacemakers, electrophysiological techniques and the implantable atrial defibrillator, show great promise. Despite paroxysmal AF being a common condition, management strategies are limited by evidence from small randomized trials, with inconsistencies over the definition of the arrhythmia and the inclusion of only symptomatic subjects. Evidence for antithrombotic therapy is also based on epidemiological studies and subgroup analyses of the large randomized trials.
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3,548
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Intravenous BQ-123 and phosphoramidon reduce ventricular ectopic beats and myocardial infarct size in dogs submitted to coronary occlusion and reperfusion.
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The aim of this work was to investigate the influence of endothelin on myocardial ischemia and reperfusion in anaesthetized dogs. Animals were submitted to left thoracotomy and 120 min of left anterior descending coronary occlusion, followed by 180 min of reperfusion. Arterial blood pressure and electrocardiogram (ECG) were recorded in order to analyze heart rate (HR)-pressure product and production of ectopic beats. Infarcted areas were identified by a macroscopic staining method and infarct size was expressed as percentage of risk zone. To inhibit the effects of endothelin in a group of animals, we administered intravenously an endothelin synthesis inhibitor (phosphoramidon) and in another group, an endothelin-1 A receptor blocker (BQ-123). Phosphoramidon decreased the HR-pressure product during reperfusion period, and both, phosphoramidon and BQ-123 decreased infarct size by 40% and the number of ventricular ectopic beats by 88% and 68%, respectively, as compared to the saline treated dogs. In conclusion, endothelin seems to play a deleterious role on the myocardium submitted to ischemia and reperfusion.
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3,549
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Impaired autonomic function predicts dizziness at onset of paroxysmal atrial fibrillation.
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Paroxysmal atrial fibrillation is associated with various symptoms, including dizziness, which presumably reflects hemodynamic deterioration. Given the importance of the autonomic nervous system in mitigating the hemodynamic effect of atrial fibrillation, we hypothesized that autonomic function would be predictive of the severity of dizziness.</AbstractText>The study group comprised 73 patients with paroxysmal atrial fibrillation (mean age 54.1 years, 51 males). Forty-three (59%) patients had lone atrial fibrillation. Mean ventricular rate during atrial fibrillation was 99+/-16 beats/min. On average, patients had a 3-year history of one paroxysm per week lasting 2 h. Autonomic function was assessed using autonomic function tests, including noninvasive measurement of baroreflex sensitivity. Head up tilting was used to test vasovagal reactivity. Severity of dizziness at onset of atrial fibrillation was quantified by the patients using a five-point scale (1=none; 2=light; 3=mild; 4=moderate; and 5=severe). Multivariate analysis was performed to identify the independent predictors of the severity of dizziness.</AbstractText>Mean severity of dizziness was 3.36+/-1.65. Multivariate predictors of moderate-to-severe dizziness as opposed to none-to-mild dizziness were a low 30-15 ratio after standing up and low baroreflex sensitivity. Though syncope was never reported nine patients showed a full vasovagal response during head up tilting.</AbstractText>It is concluded that dizziness in patients with "treated" atrial fibrillation in the setting of none to mild structural heart disease is predicted by impaired autonomic function. Vasovagal reactivity appears not to be involved in this connection.</AbstractText>
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3,550
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Atrial fibrillation-induced atrial contractile dysfunction: a tachycardiomyopathy of a different sort.
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Although AF-induced atrial contractile dysfunction has significant clinical implications the underlying intracellular mechanisms are poorly understood.</AbstractText>From the right atrial appendages of 59 consecutive patients undergoing mitral valve surgery (31 in SR, 28 in chronic AF) thin muscle preparations (diameter<0.7 mm) were isolated. Isometric force of contraction was measured in the presence of different concentrations of Ca(2+) and isoprenaline. To assess the function of the sarcoplasmic reticulum, the force-frequency relationship and the post-rest potentiation were studied. The myocardial density of the ryanodine-sensitive calcium release channel (CRC) of the sarcoplasmic reticulum was determined by [3H]ryanodine binding. Myocardial content of SR-Ca(2+)-ATPase (SERCA), phospholamban (Plb), calsequestrin (Cals) and the Na(+)/Ca(2+)-exchanger (NCX) were analyzed by Western blot analysis. Adenylyl cyclase activity was measured with a radiolabeled bioassay using [32P]ATP as a tracer.</AbstractText>In 72 muscle preparations of SR patients contractile force was 10.9+/-1.8 mN/mm(2) compared to 3.3+/-0.9 mN/mm(2) (n=48, P<0.01) in AF patients. The positive inotropic effect of isoprenaline was diminished but the stimulatory effect on relaxation and the adenylyl cyclase were not altered in AF patients. The force-frequency relation and the post-rest potentiation were enhanced in atrial myocardium of AF patients. The protein levels of CRC, SERCA, Plb, and Cals were not different between the two groups. In contrast, the Na(+)/Ca(2+)-exchanger was upregulated by 67% in atria of AF patients.</AbstractText>AF-induced atrial contractile dysfunction is not due to beta-adrenergic desensitization or dysfunction of the sarcoplasmic reticulum and thus is based on different cellular mechanisms than a ventricular tachycardia-induced cardiomyopathy. Instead, downregulation or altered function of the L-type Ca(2+)-channel and an increased Ca(2+) extrusion via the Na(+)/Ca(2+)-exchanger seem to be responsible for the depressed contractility in remodeled atria.</AbstractText>
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3,551
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[QT prolongation and torsade de pointes tachycardia during therapy with maprotiline. Differential diagnostic and therapeutic aspects].
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A 69-year-old somnolent woman developed severe heart failure, aggravated by recurrent episodes of ventricular tachycardia. The patient showed central and peripheral edema. 24 hours earlier, she had suffered cerebral seizures that were successfully terminated by phenytoin. For 13 years, persistent atrial fibrillation had been frequency-controlled with antiarrhythmic drugs (verapamil and glycosides) and treated by oral anticoagulation. In addition, there had been long-term anti-depressant therapy with the tetracyclic agent maprotiline.</AbstractText>Torsade de pointes tachycardia was documented in the electrocardiograms. In addition, the QT interval was extensively prolonged (QTc = 0.70 sec). Neither electrolyte disturbances nor acute cardiac ischemia were seen. Echocardiography revealed a highly reduced ejection fraction of 25 % and a moderately dilated left ventricle. Angiography showed a collateralized occlusion of the right and plaques of the left coronary artery.</AbstractText>Repeated torsade de pointes tachycardia resulted in hemodynamic compromise and were terminated by defibrillations. After intravenous magnesium and xylocaine administration as well as with termination of maprotiline and antiarrhythmic co-medication, QT prolongation decreased. In addition, the recurrent torsade de pointes tachycardia stopped. Subsequently, however, there were several bradycardia episodes, QT duration remained long. Accordingly, a VVI pacemaker was implanted. Up to now, the patient is doing well.</AbstractText>With antidepressant therapy, a risky constellation including comorbidity and interactions with potentially arrhythmogenic drugs may lead to QT prolongation. Medication that delays conduction or causes bradycardia may generally favour torsade de pointes tachycardia. In case of indispensable multi-drug therapy, regular clinical as well as electrocardiographic monitoring with special emphasis on QT interval is mandatory.</AbstractText>
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3,552
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Rectification of the background potassium current: a determinant of rotor dynamics in ventricular fibrillation.
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Ventricular fibrillation (VF) is the leading cause of sudden cardiac death. Yet, the mechanisms of VF remain elusive. Pixel-by-pixel spectral analysis of optical signals was carried out in video imaging experiments using a potentiometric dye in the Langendorff-perfused guinea pig heart. Dominant frequencies (peak with maximal power) were distributed throughout the ventricles in clearly demarcated domains. The fastest domain (25 to 32 Hz) was always on the anterior left ventricular (LV) wall and was shown to result from persistent rotor activity. Intermittent block and breakage of wavefronts at specific locations in the periphery of such rotors were responsible for the domain organization. Patch-clamping of ventricular myocytes from the LV and the right ventricle (RV) demonstrated an LV-to-RV drop in the amplitude of the outward component of the background rectifier current (I(B)). Computer simulations suggested that rotor stability in LV resulted from relatively small rectification of I(B) (presumably I(K1)), whereas instability, termination, and wavebreaks in RV were a consequence of strong rectification. This study provides new evidence in the isolated guinea pig heart that a persistent high-frequency rotor in the LV maintains VF, and that spatially distributed gradients in I(K1) density represent a robust ionic mechanism for rotor stabilization and wavefront fragmentation.
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3,553
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Sodium bicarbonate improves the chance of resuscitation after 10 minutes of cardiac arrest in dogs.
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The likelihood of successful defibrillation and resuscitation decreases as the duration of cardiac arrest increases. Prolonged cardiac arrest is also associated with the development of acidosis. These experiments were designed to determine whether administration of sodium bicarbonate and/or adrenaline in combination with a brief period of cardiopulmonary resuscitation (CPR) prior to defibrillation would improve the outcome of prolonged cardiac arrest in dogs. Ventricular fibrillation (VF) was induced by a.c. shock in anaesthetised dogs. After 10 min of VF, animals received either immediate defibrillation (followed by treatment with bicarbonate or control) or immediate treatment with bicarbonate or saline (followed by defibrillation). Treatment with bicarbonate was associated with increased rates of restoration of spontaneous circulation. This was achieved with fewer shocks and in a shorter time. Coronary perfusion pressure was significantly higher in NaHCO3-treated animals than in control animals. There were smaller decreases in venous pH in NaHCO3-treated animals than in controls. The best outcome in this study was achieved when defibrillation was delayed for approximately 2 min, during which time NaHCO3 and adrenaline were administered with CPR. The results of the present study indicate that in prolonged arrests bicarbonate therapy and a period of perfusion prior to defibrillation may increase survival.
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3,554
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Use of a cardiocerebral-protective drug cocktail prior to countershock in a porcine model of prolonged ventricular fibrillation.
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This was the third study in a series exploring whether the use of combination pharmacotherapy with delayed countershock would produce higher rates of return of spontaneous circulation (ROSC) and one-hour survival when compared with standard advanced cardiac life support (ACLS) therapy in prolonged ventricular fibrillation (VF).</AbstractText>Twenty-four female, mixed-breed, domestic swine (ranging in mass from 22 to 25 kg) were used in this prospective, blinded, randomized, experimental trial. Animals were sedated (ketamine/xylazine), anesthetized (alpha-chloralose), paralyzed (pancuronium), mechanically ventilated with room air, and monitored with electrocardiography, arterial pressure, and Swan-Ganz catheters. VF was induced with a 3 s, 60 Hz, 100 mA transthoracic shock, and remained untreated for 8 min. One minute of basic life support followed (standardized by use of a mechanical device). At 9 min, animals were treated with one of three regimes: Group 1, cardiocerebral-protective cocktail (antioxidant U-74389G (3.0 mg/kg), epinephrine (0.2 mg/kg), lidocaine (1.0 mg/kg), bretylium (5.0 mg/kg), magnesium (2.0 g), and propranolol (1.0 mg)); Group 2, magnesium (2.0 g); and Group 3, standard ACLS. Groups 1 and 2 received drugs at minute nine (first countershock at minute 11), while Group 3 received first countershock at minute nine. Data were analyzed with two-tailed Fisher's exact tests.</AbstractText>ROSC was achieved in Group 1, 7/7 (100%); Group 2, 3/9 (33%, P versus Group 1=0.01); and Group 3, 3/8 (38%; P versus Group 1=0.02). One-hour survival was attained in Group 1, 7/7 (100%); Group 2, 3/9 (33%; P versus Group 1=0.01), and Group 3, 1/8 (13%; P versus Group 1=0.001).</AbstractText>Combination pharmacotherapy with a cardiocerebral-protective drug cocktail prior to countershock produced superior rates of ROSC and one-hour survival when compared with singular drug therapy (Group 2) and standard ACLS (Group 3) in this porcine model of prolonged VF.</AbstractText>
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3,555
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Pathological features of witnessed out-of-hospital cardiac arrest presenting with ventricular fibrillation.
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To determine which characteristic pathological features are predictive of the presenting rhythm and survival in victims of community cardiac arrest.</AbstractText>Case-controlled retrospective autopsy study.</AbstractText>County of Nottinghamshire with a total population of 993 914 and an area of 2183 square kilometers.</AbstractText>Between January 1, 1991 and December 31, 1994, 1535 witnessed cardiac arrests attended by the Nottinghamshire Ambulance Service, of which 1083 had an autopsy performed.</AbstractText>Ischaemic heart disease accounted for 72.3% of cases with a further 3.6% of deaths from other cardiac causes and the remainder from non-cardiac causes. Old healed myocardial infarction was present in 39.4%, and visible fresh occlusive thrombus was found in 23.8% of cases overall. Logistic regression analysis of deaths from cardiac causes revealed that younger age (odds ratio of 0.98 (95% CI 0.97-0.99)), two vessel coronary artery disease (odds ratio of 1.65 (95% CI 1.08-2.52)) and heart weight greater than 500 grams (odds ratio of 1.56 (95% CI 1.12-2.17)) were found to be independent predictors of developing ventricular fibrillation compared to other rhythms of arrest. Being male, visible occlusive thrombus and having survived a previous myocardial infarction were found not to be independent variables. There were no outstanding pathological features in the 31 patients who survived to hospital admission and subsequently died, compared with non-survivors who were considered to have died from a cardiac cause.</AbstractText>Among those who had a witnessed out-of-hospital cardiac arrest from a cardiac cause, increasing heart weight (the most likely cause of which is left ventricular hypertrophy), younger age and two vessel coronary artery disease appear to be much more important pathological features in the development of ventricular fibrillation than a previous myocardial infarction and fresh visible occlusive thrombus.</AbstractText>
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3,556
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The Utstein template and the effect of in-hospital decisions: the impact of do-not-attempt resuscitation status on survival to discharge statistics.
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Variables for reporting outcome of pre-hospital cardiac arrest have been delineated in the Utstein style template. The primary outcome statistic is survival to hospital discharge (SHD). The template allows comparisons of pre-hospital care systems and has been used to determine the benefit of pre-hospital interventions. Post-resuscitation care has not been standardized and in-hospital events that affect SHD are not considered in the template.</AbstractText>To determine the frequency and timing with which do-not-attempt resuscitation (DNAR) status is conferred following resuscitation from pre-hospital cardiac arrest and to assess the impact of this action on SHD.</AbstractText>A 4-year retrospective, observational cohort study of all adult patients successfully resuscitated from nontraumatic pre-hospital cardiac arrest and admitted to a single municipal teaching hospital. Study variables included age, witnessed arrest, bystander cardiopulmonary resuscitation (CPR), initial rhythm documented by paramedics, hospital admission rate, frequency and time at which DNAR status was conferred, and SHD.</AbstractText>Four hundred and eighteen adult patients experienced pre-hospital arrest and received standard advanced cardiac life support interventions during the study period. Seventy-nine patients (19%; 95% confidence interval (CI), 15-23%) survived to be admitted to the hospital. Fifty-four of these patients (68%; 96% CI, 57-78%) were subsequently placed in DNAR status. Only one of these patients had a living will or advanced directive prior to cardiopulmonary arrest. In 37 DNAR patients (68%; 95% CI, 54-81%), DNAR status was conferred within 24 h of hospital admission. For patients made DNAR within 24 h of admission, 38% had a witnessed arrest, 22% had ventricular fibrillation as the first documented arrest rhythm, and 29% received bystander CPR. When patients made DNAR are included in the calculation of SHD rate, the SHD rate for the study period was 5.3% (95% CI, 3.3-7.8%). If DNAR patients are excluded, the SHD was 6.1% (95% CI, 3.8-9.0%), representing a 15% increase in SHD rate.</AbstractText>In-hospital care and medical decision making are not considered in the Utstein template and can have a significant effect on reported survival statistics. When assessing the benefit of pre-hospital interventions, it may be preferable to consider survival to hospital admission as the primary outcome statistic until such time as post-resuscitation care after hospital admission is rigidly standardized.</AbstractText>
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3,557
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Adrenergic nervous activity in patients after surgical correction of tetralogy of Fallot.
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The study was done to define the role of the autonomic nervous system in postoperative tetralogy of Fallot.</AbstractText>Subsequent to surgical correction of tetralogy of Fallot, patients are at long-term risk of sudden death owing to ventricular electrical instability. The status of the sympathetic nervous system in these patients, known to play an important role in other patients at risk, remains unknown.</AbstractText>We used (123)I metaiodobenzylguanidine (MIBG) with tomographic imaging, combined with assessment of heart rate variability (HRV), to evaluate the activity of the sympathetic nervous system. We analyzed 22 patients who had undergone total correction of tetralogy of Fallot: 13 with either no or minor ventricular arrhythmias, and 9 with sustained ventricular tachycardia or ventricular fibrillation.</AbstractText>Analysis of HRV revealed a reduction in vagal control and sympathetic dominance in all patients compared with a healthy control group of 20 subjects. A significant difference was found in the standard deviation of all the adjacent intervals between normal beats (SDNN) in patients with or without severe ventricular arrhythmias. A significant reduction in uptake of (123)I MIBG was demonstrated 30 min after IV injection, and a trend toward reduction after 5 h, associated with reduced washout indices. These data reflect a decrease in the number of nerve endings in the right and left ventricular walls, and an inhomogeneous distribution of the adrenergic nervous system. The uptake of MIBG was significantly reduced in the patients at risk of ventricular tachycardia or fibrillation.</AbstractText>Subsequent to surgical correction of tetralogy of Fallot, the positive correlation between myocardial uptake of MIBG, SDNN and the QRS dispersion confirmed the usefulness of analysis of the adrenergic nervous system to stratify patients at risk of life-threatening arrhythmias.</AbstractText>
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3,558
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Long-term left ventricular pacing: assessment and comparison with biventricular pacing in patients with severe congestive heart failure.
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The purpose of this study is to report prospectively the results of six-month follow-up of permanent left ventricular (LV) based pacing in patients with severe congestive heart failure (CHF) and left bundle branch block (LBBB).</AbstractText>Left ventricular pacing alone has been demonstrated to result in identical improvement compared to biventricular pacing (BiV) during acute hemodynamic evaluation in patients with advanced CHF and LBBB. However, to our knowledge, the clinical outcome during permanent LV pacing alone versus BiV pacing mode has not been evaluated.</AbstractText>Pacing configuration (LV or BiV) was selected according to the physician's preference. Patient evaluation was performed at baseline and at six months.</AbstractText>Thirty-three patients with advanced CHF and LBBB were included. Baseline characteristics of LV (18 patients) and BiV (15 patients) pacing groups were similar. During the six-month follow-up period, seven patients died three BiV and four LV). In the surviving patients at 6 months, 8 of 14 patients in the LV group and 9 of 12 in the BiV group were in New York Heart Association class I or II (p = 0.39). No significant difference was observed between the two groups in terms of objective parameters except for LV end-diastolic diameter decrease (-4.4 mm in BiV group vs. -0.7 mm in LV group; p = 0.04).</AbstractText>At six-month follow-up, a trend toward improvement was observed in objective parameters in patients with severe CHF and LBBB following LV-based pacing. The two pacing modes (LV and BiV) were associated with almost equivalent improvement of subjective and objective parameters.</AbstractText>
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3,559
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Cardioprotective effects of the MR contrast agent MnDPDP and its metabolite MnPLED upon reperfusion of the ischemic porcine myocardium.
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To evaluate whether manganese dipyridoxyl diphosphate (MnDPDP) or its metabolite manganese dipyridoxyl ethyldiamine (MnPLED) reduces post-ischemic myocardial injury.</AbstractText>Left anterior descending artery (LAD) in anesthetized pigs was occluded (30 min) followed by reperfusion (120 min) during hemodynamic monitoring and infarct assessment. Three micromol/kg MnDPDP, 1 micromol/kg MnPLED (or a mixture of both) or saline was injected i.v. 10 min before reperfusion followed by infusion of either 3 micromol/kg/h MnDPDP, 1 micromol/kg/h MnPLED (or a mixture of both) or saline. The plasma concentrations of MnDPDP, MnPLED and other metabolites (e.g., ZnDPDP and ZnPLED) were analyzed.</AbstractText>Femoral blood flow was reduced by 60% during early reperfusion in controls, whereas only 23 and 31% reductions were seen in animals treated with MnDPDP and MnPLED. During that time, +LV/dP and -LV/dP (maximum rate of left ventricular isovolumic contraction and relaxation, respectively), systolic pressure and diastolic pressure fell significantly less in animals treated with MnDPDP or MnPLED. Three out of 5 control animals experienced ventricular fibrillation (VF) during reperfusion, whereas VF was not seen in any of the pigs treated with MnPLED or/and MnDPDP. The infarct sizes in saline- and MnPLED-treated animals were 39+/-6 and 16+/-5%, respectively, of the occluded areas. MnDPDP did not reduce the infarct size. A mixture of MnDPDP and MnPLED significantly reduced infarct size (10+/-4%). When reperfusion started and throughout reperfusion, almost all injected MnDPDP was present as Zn-metabolites.</AbstractText>MnPLED seems to reduce reperfusion-induced cardiac dysfunction and infarct size in pigs. MnDPDP does not reduce infarct size in the pig, probably because of the rapid exchange of Mn2+ for Zn2+ taking place in the pig.</AbstractText>
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3,560
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Anti-arrhythmic and electrophysiological effects of the endothelin receptor antagonists, BQ-123 and PD161721.
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The effects of the endothelin ET(A), (BQ-123) and endothelin ET(A/B) (PD161721) receptor antagonists were investigated on ischaemia-induced arrhythmias and on the maximum following frequency. The study was carried out in Langendorff perfused rat hearts subjected to coronary artery occlusion in which the severity of arrhythmias, coronary perfusion pressure and heart rate were measured. The % incidence of ischaemia-induced irreversible ventricular fibrillation (ventricular fibrillation) was reduced significantly from 58%, in control rat hearts, to 0% (at 10(-7) and 10(-6) M PD161721 and 10(-6) M BQ-123 P<0.05). Maximum following frequency was measured in guinea-pig isolated atria. In the presence of normal extracellular [K(+)], BQ-123 and PD161721, at 10(-6) M, significantly decreased the maximum following frequency from 9.0+/-0.7 to 7.2+/-0.4 and from 8.3+/-0.4 to 6.7+/-0.3 Hz, respectively (P<0.05). These effects were not potentiated by raising the extracellular [K(+)] with the exception of 10(-9) M PD161721. In contrast, lignocaine's ability to reduce the maximum following frequency was greater in elevated (e.g. at 1.7x10(-4) M from 8.4+/-0.3 to 2.5+/-0.6 Hz) than in normal [K(+)] (from 9.0+/-0.3 to 4.9+/-0.5 Hz). In conclusion, both BQ-123 and PD161721 had an anti-fibrillatory effect in isolated rat hearts that may be due, at least in part, to an ability to reduce the maximum following frequency. This latter effect is unlikely to be due to Na(+) channel blockade since it was not markedly potentiated by elevation of extracellular [K(+)].
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3,561
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Percutaneous mitral balloon valvotomy: six-year follow-up.
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Percutaneous mitral valvotomy (PMV) is an alternative to the surgical treatment of mitral stenosis. Results obtained with PMV appear to depend on the echocardiographical characteristics of the valvular apparatus. The purpose of this study was to report the immediate and late-term results with PMV. The incidence of late events (restenosis, mitral valve replacement and death), and their correlation with echocardiographic score (Wilkin's score) are also discussed.</AbstractText>Between December 1987 and August 1999, a total of 160 PMVs were performed at our institution. Ninety-six patients with a minimum of 6 months follow-up and echocardiographic evaluation of the mitral valve (Wilkin's score) before and after the procedure were selected for this study. Follow-up was available for 99% of the patients, with a mean follow-up of 33 +/- 22 months (range, 6 months to 11 years). Hazard ratio (HR) and Cox's regression were used for statistical analyses.</AbstractText>PMV was successfully performed in 97% of the cases; in 84%, the result was considered optimal. The incidence of complications related to the procedure was 10%; no mortality was observed due to PMV. Severe mitral regurgitation was observed in 7% of the patients, but only 3% of the total group developed ventricular dysfunction or worsened their New York Heart Association functional class. Eight-four percent of the patients were free of late events at the end of the follow-up period. A restenosis rate of 34% was observed during follow-up; this rate did not correlate with age, functional class or atrial fibrillation. Restenosis was associated with pulmonary hypertension (HR 2.85; 95% confidence interval, 0.68-11.80). Also, Wilkin's score was not useful to predict the development of restenosis or clinical events in the mid- to long-term.</AbstractText>In our series, PMV had a high immediate success rate and a low incidence of complications due to the procedure. Incidence of late events was also low and was unrelated to the Wilkin's score; however, recurrence of stenosis was observed in one-third. Pulmonary hypertension should be considered to be an important clinical predictor of restenosis.</AbstractText>
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3,562
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Automated external defibrillators: technical considerations and clinical promise.
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Early defibrillation is the most important determinant of survival for victims of cardiac arrest due to ventricular fibrillation. The automated external defibrillator (AED) was developed as the result of the American Heart Association's Public Access Defibrillation initiative. The goal of this initiative is to place AEDs in strategic locations so that laypersons with minimal training could promptly defibrillate victims of cardiac arrest. Because of changes in design and the use of alternative waveforms for defibrillation, the modern AED is compact and portable, simple to use, and highly efficacious; in addition, it requires little maintenance. Automated external defibrillators have been used successfully by traditional and nontraditional responders as well as laypersons. In special environments, such as casinos and commercial aircraft, AEDs have performed particularly well. State and federal legislation has eased concerns about AED use by extending legal protection to AED users under Good Samaritan laws. Since the experience continues to be positive, AEDs are being used in increasingly diverse community locations, and public awareness is growing. The American Heart Association's initiative is progressing rapidly.
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3,563
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[Adequate performance of a pectoral implanted defibrillator after high-dose radiation therapy for thyroid cancer].
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The interference of implanted defibrillators (ICD) from electronic appliances is small. There is scant knowledge about the effects of radiation therapy on defibrillator function. Existing data commonly derive from in vitro tests of the devices. We report on a 60-year old male patient with a left pectoral implanted ICD, who received radiation therapy for treatment of thyroid cancer.    The patient suffered from coronary heart disease with severely impaired left ventricular function, and had to be resuscitated from ventricular fibrillation in December 1997. A defibrillator (Medtronic Jewel 7219 C) was implanted in a left pectoral pocket. In January 2000, a carcinoma of the thyroid gland was diagnosed and treated surgically. The operation was followed by a radiation therapy with curative intention. The patient received a local dosage of 64 Gray (32 sessions in 51 days). The ICD was covered by individually sized metal blocks, and was affected by 10 Gray at maximum. The ICD was inactivated during the radiation applications to avoid inadequate therapy due to electromagnetic interference. The pace-sense parameters during 8 months of follow-up were regular. Three episodes of ventricular fibrillation were terminated adequately by the ICD. Therefore, we assumed a correct ICD funtion after radiation therapy.    Radiation-induced damage of the ICD was possible. A surgical transfer of the generator out of the radiation area was rejected on ethical grounds. In the short follow-up period, the ICD function was correct. For our opinion it seems to be justified primarily to control the spontaneous outcome and ICD function at short intervals, especially in view of the poor prognosis of cancer patients.
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3,564
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New electrocardiographic leads and the procainamide test for the detection of the Brugada sign in sudden unexplained death syndrome survivors and their relatives.
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Sudden unexplained death syndrome occurs in previously healthy South-east Asian young adults without any structural cause of death. The common electrocardiographic (ECG) change in sudden unexplained death syndrome survivors is right bundle branch block and ST elevations in leads V(1) to V(3), which are similar to the ECG pattern in the Brugada syndrome (Brugada sign). It is difficult to diagnose the Brugada sign with the 12-lead ECG in sudden unexplained death syndrome survivors and their family members because the ECG could be transiently normalized. We proposed using the higher intercostal space V(1) to V(3) lead ECG, together with procainamide to detect the Brugada sign.</AbstractText>Among 20 ventricular fibrillation cardiac arrest patients, 13 sudden unexplained death syndrome survivors and their relatives (n=88) were studied using the single standard 12-lead ECG and the new six higher intercostal space V(1) to V(3) lead ECG (-V(1) to -V(3) and -2V(1) to -2V(3)). Ten sudden unexplained death syndrome survivors and relatives (n=48) who had a normalized ECG were also infused with procainamide (10 mg x kg(-1)i.v.) to unmask the Brugada sign and both ECG methods were recorded. Forty healthy individuals and 13 spouses served as the control group. Prior to the procainamide infusion, the Brugada sign could be detected in nine sudden unexplained death syndrome survivors (69.2%) and three (3.4%) relatives with the standard ECG and in 12 (92.3%) and nine (10.2%) with the new six-lead ECG. After the procainamide infusion, the Brugada sign could be demonstrated in seven sudden unexplained death syndrome survivors (70%) and seven (14.6%) relatives with the standard ECG and in nine (90%) (P=0.26) and 23 (47.9%) (P=0.0004) with the new six-lead ECG, respectively. All the controls were negative for the Brugada sign.</AbstractText>Our data suggest that the new higher intercostal space lead ECG, with or without the procainamide test is helpful in detecting the Brugada sign in sudden unexplained death syndrome survivors and their relatives.</AbstractText>Copyright 2001 The European Society of Cardiology.</CopyrightInformation>
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3,565
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[Alcohol and stroke: a controversial association].
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Although an increasing quantity of information concerning risk factors for stroke have been developed lately, the relationship between alcohol consumption and cerebral ischemic infarction, unlike at coronary sites, remains unclear. This review highlights the main pathogenic mechanisms of alcohol in the development of ischemic stroke, as it intends to be an update of this possible association.</AbstractText>A critical literature review has been performed regarding this association to study its pathogenic mechanisms and the possible confounding factors present in the current design of epidemiological reports.</AbstractText>There is an increasing evidence about the effect of light to moderate alcohol consumption and prevention of ischemic stroke. On the other hand it seems that heavy drinking, and particularly binge drinkers, are exposed to a higher risk for cardioembolic stroke. The growing incidence of acute heavy alcohol consumption highlights the necessity of considering a cardioembolic source when managing ischemic stroke, specially in young adults.</AbstractText>
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3,566
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The predictive value of ventricular fibrillation electrocardiogram signal frequency and amplitude variables in patients with out-of-hospital cardiac arrest.
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We evaluated ventricular fibrillation frequency and amplitude variables to predict successful countershock, defined as pulse-generating electrical activity. We also elucidated whether bystander cardiopulmonary resuscitation (CPR) influences these electrocardiogram (ECG) variables. In 89 patients with out-of-hospital cardiac arrest, ECG recordings of 594 countershock attempts were collected and analyzed retrospectively. By using fast Fourier transformation analysis of the ventricular fibrillation ECG signal in the frequency range 0.333-15 Hz (median [range]), median frequency, dominant frequency, spectral edge frequency, and amplitude were as follows: 4.4 (2.4-7.5) Hz, 4.0 (0.7-7.0) Hz, 7.7 (3.7-13.7) Hz, and 0.94 (0.24-1.95) mV, respectively, before successful countershock (n = 59). These values were 3.8 (0.8-7.7) Hz (P = 0.0002), 3.0 (0.3-9.7) Hz (P < 0.0001), 7.3 (2.0-14.0) Hz (P < 0.05), and 0.53 (0.03-3.03) mV (P < 0.0001), respectively, before unsuccessful countershock (n = 535). In patients in whom bystander CPR was performed (n = 51), ventricular fibrillation frequency and amplitude before the first defibrillation attempt were higher than in patients without bystander CPR (n = 38) (median frequency, 4.4 [2.4-7.5] vs 3.7 [1.8-5.3] Hz, P < 0.0001; dominant frequency, 3.8 [0.9-7.7] vs 2.6 [0.8-5.9] Hz, P < 0.0001; spectral edge frequency, 8.4 [4.8-12.9] vs 7.2 [3.9-12.1] Hz, P < 0.05; amplitude, 0.79 [0.06-4.72] vs 0.67 [0.16-2.29] mV, P = 0.0647). Receiver operating characteristic curves demonstrate that successful countershocks will be best discriminated from unsuccessful countershocks by ventricular fibrillation amplitude (3000-ms epoch). At 73% sensitivity, a specificity of 67% was obtained with this variable.</AbstractText>In patients with out-of-hospital cardiac arrest, successful countershocks will be best discriminated from unsuccessful countershocks by ventricular fibrillation amplitude (3000-ms epoch). At 73% sensitivity, a specificity of 67% was obtained with this variable.</AbstractText>
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3,567
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Evaluation of emergency air evacuation of critically ill patients from cruise ships.
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The study objectives were to assess the ship physician's diagnostic accuracy in making the decision to air evacuate critically ill patients from cruise ships, to determine the outcome of these patients, and the overall benefit of air evacuation.</AbstractText>From October 1999 to May 2000, we performed a prospective study of critically ill patients coming from cruise ships in the Caribbean and transported to our institution by air ambulance. Demographics, initial diagnosis, and treatment on board were collected by the triage officer at the time of the cruise physician's first call. In route complications and flight team composition were obtained from the air ambulance monitoring log. Patients were followed-up in the hospital for complications, outcome, and final diagnosis.</AbstractText>A consecutive series of 104 patients were considered for analysis. There were 65 men and 39 women (mean age: 68.7 years). Cruise physician's diagnosis was correct in more than 90% of the cases. Internal medicine and surgical conditions represented 80.8% and 19.2% of the cases respectively, falling mainly into three categories: cardiac (34.6%), neurological (20.2%), and digestive (14%). Two cardiac arrests and 1 ventricular fibrillation were successfully resuscitated and 5 of 15 myocardial infarctions received thrombolytic therapy on board. Air transfers were warranted in 96.1% of the cases and physician presence in the flight was considered appropriate in 97.6%. In route complications and mortality rate were 5.8% and 2.9% respectively, related to serious cardiac events. Among the 98 hospitalized patients, 10 patients developed new complications and 5 died. The overall mortality rate was 7.7%.</AbstractText>The cruise industry appears off to a good start in the medical treatment of passengers needing air evacuation to a land based medical facility. There is room for improvement and adoption of American College of Emergency Physicians (ACEP) and International Council of Cruise Lines (ICCL) Health Care Guidelines are meaningful first steps. Analysis of Caribbean medical facilities and implementation of active telemedicine conferencing represent alternatives to air evacuation that need to be studied.</AbstractText>
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3,568
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Out-of-hospital cardiac arrest in men and women.
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The incidence of sudden cardiac death is roughly 3 times greater in men than in women. However, in patients treated for out-of-hospital cardiac arrest, the relationships between sex and survival after adjustment for age and cardiac rhythm are unclear.</AbstractText>In this retrospective cohort study, we examined 7069 men and 2582 women who were treated for out-of-hospital cardiac arrest in Seattle and suburban King County between 1990 and 1998. We compared successful prehospital resuscitation (hospital admission) and survival from event to discharge in men and women. Women had markedly reduced rates of ventricular fibrillation (VF), slightly older age, fewer witnessed arrests, and fewer arrests in public locations than men. Although their unadjusted resuscitation rate was lower (29% versus 32%, P<0.0001), women had a greater likelihood of resuscitation than men after adjustment for VF (odds ratio [OR] 1.13; 95% confidence interval [CI], 1.03 to 1.25) and after adjustment for VF plus additional factors (OR, 1.27; 95% CI, 1.14 to 1.41). The difference in resuscitation rates between men and women decreased as they aged (test for trend, P<0.0001). Unadjusted survival rates were also lower in women than in men (11% versus 15%, P<0.0001). Women had similar survival after adjustment for VF (OR, 0.97; 95% CI, 0.85 to 1.11) and after adjustment for VF plus additional factors (OR, 1.09; 95% CI, 0.93 to 1.27).</AbstractText>The lower unadjusted resuscitation and survival rates observed in women were primarily due to women's lower incidence of VF, a relatively favorable cardiac rhythm. After adjustment for VF and other factors, women had higher resuscitation rates than men, but similar rates of survival from event to discharge.</AbstractText>
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3,569
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Acute pulmonary toxicity after low-dose amiodarone therapy.
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Amiodarone-induced pulmonary toxicity is usually seen in cardiac surgical patients who have received large doses of amiodarone for ventricular arrhythmias over prolonged periods. In this report, we describe a case of amiodarone-induced pulmonary toxicity after a short course of therapy for postoperative atrial fibrillation.
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3,570
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Atrial fibrillation surgery simplified with cryoablation to improve left atrial function.
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The Maze procedure restores atrial fibrillation to normal sinus rhythm. However, concurrent left atrial functional recovery is not always achieved. To address this limitation, a modification using linear cryoablation is described.</AbstractText>Between July 1997 and December 1999, 83 patients received atrial fibrillation surgery in association with mitral valve surgery with or without additional concurrent procedures by either the conventional technique, group I (n = 30) or the modified technique, group II (n = 53). Onset of sinus conversion and echocardiographic assessment of postoperative left ventricular function, left atrial size, and mitral A-wave velocity were compared in the early postoperative period and 6 months after surgery.</AbstractText>Sinus conversion occurred significantly earlier in group II, 2.4 +/- 5 days versus group I, 7.0 +/- 10 days. The mean transmitral A-wave velocity and the incidence of A-wave appearance in the early postoperative period and 6 months postoperatively were greater in group II than group I.</AbstractText>With the current modification, restoration of sinus rhythm and superior left atrial contractile function occurred earlier than with the standard Maze III technique.</AbstractText>
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3,571
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Does electrode polarity alter the energy requirements for transthoracic biphasic waveform defibrillation? Experimental studies.
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Electrode polarity may alter the success of biphasic shocks from implantable systems. Whether the electrode polarity influences the success of transthoracic biphasic defibrillation is unknown. We determined the effect of electrode polarity on biphasic transthoracic defibrillation in a porcine model.</AbstractText>In ten anesthetized adult pigs, 16-28 kg, electrode pads were placed in two different orientations on the chest wall; apex-right parasternal and sternal-vertebral column. Ventricular fibrillation (VF) was electrically induced and allowed to persist for 30 s. Truncated exponential biphasic shocks (5/3 ms) were delivered at 20, 30, 50, 70 and 100 J. Four shocks at each energy level were delivered to construct energy vs. % success curves for VF termination. Electrode polarity for the first pulse was varied so that the first pulse cathode was either the apex (for apex-parasternal) or sternum (for sternum-vertebral column), or the reverse. The second pulse polarity was always the opposite of the first.</AbstractText>VF termination success rose from 0 to 86% as energy increased from 20 to 100 J. Varying the electrode polarity did not alter success rates at any energy level with either electrode pad placement.</AbstractText>In this porcine model of transthoracic defibrillation, varying the biphasic shock electrode polarity did not alter transthoracic defibrillation success. Positional labeling of transthoracic biphasic defibrillation electrode pads may be unnecessary.</AbstractText>
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3,572
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Novel CPR with periodic Gz acceleration.
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The effects of periodic Gz acceleration (pGz) on cardiovascular function and hemodynamics were determined in a pig model of acute cardiopulmonary resuscitation (CPR). The application of pGz (horizontal head-to-foot oscillations) at 2 Hz increased cardiac output in fibrillated animals proportional to the amplitude of the applied acceleration force that plateaued at 0.7 G. Cardiac output in fibrillating animals was restored to 20% of the values obtained before fibrillation with pGz-CPR and arterial blood gas values were normal during this period. The central vascular pressure gradient driving blood flow was only about 6 mmHg, suggesting low vascular resistance during pGz-CPR. In another study, capillary blood flow was determined before and after pGz-CPR using colored microspheres. Capillary perfusion was detected in all tissue beds studied during pGz-CPR. Significant capillary blood flow was detected in the endocardium and brain stem during pGz-CPR that represented 39 and 197% of control values before fibrillation, respectively. Thus, the cardiac output during pGz-CPR was preferentially distributed to the myocardial and brain tissues. In a final group, animals were successfully resuscitated with return of spontaneous circulation (ROSC) after pGz-CPR for 15 min following cardiac fibrillation with a 3-min non-intervention period. Following ROSC, blood pressure was maintained at pre-arrest values for 2 h without any pharmacological or mechanical support. Arterial blood gases during the pGz-CPR and the ROSC periods were normal and not different from values obtained before fibrillation. None of the control animals (18 min of fibrillation without pGz-CPR) survived the experimental protocol and only two of these six animals briefly returned to spontaneous circulation (<20 min). In conclusion, experimental pGz-CPR produces cardiac output, capillary blood flow, and ventilation sufficient to maintain fibrillating animals for 18 min with ROSC for 2 h without support.
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3,573
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Cardiac arrest patients in an alpine area during a six year period.
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The components of the 'chain of survival' remain the strongest pathway to save more people from out-of-hospital cardiac arrest. The 'Utstein Style' terminology has been applied to this study to evaluate survival in patients cared for by Emergency Medical Technicians--Defibrillation (EMT-D) and physicians in a rural alpine area.</AbstractText>Over a 6-year period in a descriptive observational study with prospective data collection special efforts were made to identify weaknesses in the 'links' of our emergency cardiac care system considering the special geographical and legal aspects. Data from all emergency calls dispatched by the ambulance centre for patients with cardiac arrest were collected and are presented as a median and interquartile range.</AbstractText>We recorded 368 cardiac arrests and in 338 patients resuscitation was attempted. Ventricular fibrillation (VF) was observed in 118 patients (35%), of whom 13 (4%) were defibrillated by EMT-Ds and 105 (31%) by physicians. Response times were 1 (0,2) min to call, 8 (6-11) min to arrival of first tier and 16 (10-26) min to defibrillation. Restoration of spontaneous circulation was achieved in 54 (46%) VF-patients. In EMT-D vs. physician treated VF-patients 1 year survival was 1 (8%) versus 20 (19%).</AbstractText>With the exception of publications on avalanche victims and mountaineers, there are no reports of patients with out-of-hospital cardiac arrest in alpine areas. Response intervals and survival rate are not as poor as might be expected and are similar to metropolitan areas.</AbstractText>
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3,574
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Cerebral ischaemia in experimental cardiopulmonary resuscitation--comparison of epinephrine and aortic occlusion.
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The apparent inability of epinephrine to improve outcome after cardiopulmonary resuscitation (CPR) could be caused by direct negative effects on the cerebral circulation. Constant aortic occlusion with a balloon catheter could be an alternative way to improve coronary and cerebral perfusion during CPR. The objective of the present study was to compare the effects of standard-dose epinephrine with balloon occlusion of the descending aorta on cortical cerebral blood flow augmentation during CPR. Ventricular fibrillation was induced in 24 anaesthetised piglets. A non-intervention interval of 9 min was followed by open-chest CPR. The animals were randomised to receive repeated intravenous bolus doses of epinephrine 20 microg/kg or balloon occlusion of the descending aorta. Focal cortical cerebral blood flow was measured continuously using laser-Doppler flowmetry. Balloon occlusion of the aorta resulted in a significantly higher mean cortical cerebral blood flow and a lower cerebral oxygen extraction ratio than epinephrine during CPR. After restoration of spontaneous circulation the cerebral perfusion appeared compromised to the same extent in both groups, with lower blood flow compared to baseline, high cerebral oxygen extraction and cerebral tissue acidosis. No difference in cerebral cortical vascular resistance between the two groups could be detected. It is concluded that aortic balloon occlusion was superior to epinephrine in cerebral blood flow augmentation during resuscitation and did not generate adverse effects on cerebral blood flow, oxygenation or tissue pH after restoration of spontaneous circulation. No evidence of cerebral vasoconstriction induced by standard-dose epinephrine was found.
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3,575
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Preliminary results on the prediction of countershock success with fibrillation power.
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In a study of artifact-free ventricular fibrillation episodes in 54 patients, 28 of whom experienced return of spontaneous circulation (ROSC), the power of different indicators to predict the ROSC was compared. Taking the average of sensitivity, specificity and positive and negative predictive value, the dominant frequency reaches 76%, the mean amplitude 72% and fibrillation power 71%. There is little correlation between the three indicators.
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3,576
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Fibrillation power, an alternative method of ECG spectral analysis for prediction of countershock success in a porcine model of ventricular fibrillation.
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Noninvasive prediction of defibrillation success after cardiac arrest and cardiopulmonary resuscitation (CPR) may help in determining the optimal time for a countershock, and thus increase the chance for survival.</AbstractText>In a porcine model (n=25) of prolonged cardiac arrest, advanced cardiac life support was provided by administration of two or three doses of either vasopressin or epinephrine after 3 or 8 min of basic life support. After 4 min of ventricular fibrillation and 18 min of life support, defibrillation was attempted. The denoised power spectral density of 10 s intervals of the ventricular fibrillation electrocardiogram (ECG) was estimated from averaged and smoothed Fourier transforms. We have eliminated the spectral contribution of artifacts from manual chest compressions and provide a definition for the contribution of ventricular fibrillation to the power spectral density. This contribution is quantified and termed "fibrillation power".</AbstractText>We tested fibrillation power and two established methods in their discrimination of survivors (n=16) vs. non-survivors (n=9) in the last minute before the countershock. A fibrillation power > or =79 dB predicted successful defibrillation with sensitivity, specificity, positive predictive value and negative predictive value of 98%, 98%, 99% and 97% while a mean fibrillation frequency > or =7.7 Hz was predictive with 85%, 83%, 90% and 77% and a mean amplitude > or =0.49 mV was predictive with 95%, 90%, 94% and 91%.</AbstractText>We suggest that fibrillation power is an alternative source of information on the status of a fibrillating heart and that it may match the established mean frequency and amplitude analysis of ECG in predicting successful countershock during CPR.</AbstractText>
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3,577
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Estimating the effect of bystander-initiated cardiopulmonary resuscitation in Japan.
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Low incidence of bystander-initiated cardiopulmonary resuscitation (CPR) is allegedly responsible for poor survival from out-of-hospital cardiac arrest (OHCA) in Japan. This study was conducted to determine significant predictors for survival after collapse-witnessed OHCA of presumed cardiac etiology to investigate the impact of bystander-initiated CPR. Logistic regression analysis of OHCA of presumed cardiac etiology was performed on retrospective data sets from three Japanese suburban communities. All arrest incidents were witnessed and occurred prior to the arrival of EMS personnel. Outcome measure was survival to discharge. Initial electrocardiogram (ECG) rhythm (ventricular fibrillation (VF) or not), interval from collapse to CPR (within 5 min or not), and initial ECG rhythm/collapse-to-CPR interval interaction were significantly associated with survival. Patient age (70 years or less/over 70 years), interval from collapse to EMS response, and bystander-initiated CPR were significantly associated with VF in an initial ECG. The effectiveness of bystander-initiated CPR for OHCA can be successfully predicted based on the interval from collapse to CPR and initial ECG rhythm. The increase in the proportion of bystander-initiated CPR from the present level of 20-50% would be expected to rescue another 1800 victims of OHCA per year in Japan.
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3,578
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The use of AEDs by police officers in the City of London. Automated external defibrillators.
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The Guidelines 2000 for cardiopulmonary resuscitation recommend shock delivery to victims in ventricular fibrillation within 5 min of call receipt by the Emergency Medical Services. In an effort to achieve this goal, in some parts of the United States, police officers have been trained to use automated external defibrillators (AEDs). We undertook a 3-year pilot evaluation of the use of AEDs by City of London police (CPOL) officers. Over a period of 3 years, 147 CPOL officers were trained in the use of an AED. Four AEDs were placed on rapid response vehicles covering the City of London. An overall call-response interval target was set at 8 min. The CPOL attended 1103 (90%) of the total of 1232 calls to which they were summoned. The mean interval between the first call received and arrival of the CPOL on scene was 8.9+/-4.0 min. The CPOL applied AEDs to 25 victims, 13 of whom were initially in ventricular fibrillation; at least one shock was delivered to all 13. The interval between call reception and delivery of the first shock was 5.5+/-2.5 min. The mean interval between switching on the AED and delivery of the first shock was 24+/-12 s. Two (15%) of these victims survived to hospital discharge. This study has confirmed the feasibility of training police officers in the UK to use AEDs as first responders. The call received to arrival on scene interval should be reduced by improvements in communication between LAS and CPOL.
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3,579
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Biphasic and monophasic transthoracic defibrillation in pigs with acute left ventricular dysfunction.
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Our purpose was to compare biphasic versus monophasic shock success for VF termination in a porcine model of acute left ventricular (LV) dysfunction.</AbstractText>For the termination of ventricular fibrillation (VF), transthoracic biphasic waveform shocks achieve higher success rates than monophasic shocks. However, the effectiveness of biphasic versus monophasic defibrillation in a setting of left ventricular dysfunction has not been reported.</AbstractText>In 23 open-chest adult swine (15-25 kg), LV dysfunction [> or =25% decline in cardiac output (CO)] was induced by continuous inhalation of halothane (1-1.75%). Each pig randomly received transthoracic biphasic and monophasic shocks at three energy levels (30, 50 and 100 J) in two conditions: baseline and LV dysfunction. Halothane effect on left ventricular size and contraction was measured by echocardiography in three additional swine.</AbstractText>With halothane, pigs demonstrated a decline in CO (baseline 4.16+/-0.19, halothane 2.72+/-0.19 l/min, P<0.01), mean arterial pressure (baseline 107.2+/-3.5, halothane 80.1+/-3.4 mmHg, P<0.01) and increased left ventricular end-diastolic pressure (baseline 6.4+/-0.9, halothane 12.7+/-0.8 mmHg, P<0.01). LV diameters increased and fractional shortening fell. During baseline, biphasic shocks achieved significantly greater success (termination of VF) compared to monophasic waveforms (100 J: biphasic 83.3+/-9.5 versus monophasic 38.9+/-9.5%, P<0.01; 50 J: biphasic 67.1+/-8.8 versus monophasic 11.8+/-5.7%, P<0.01; 30 J: biphasic: 31.9+/-6.4 versus monophasic 0+/-0%, P<0.01). The superiority of the biphasic waveform to terminate VF was retained during LV dysfunction at all energy levels (100 J: biphasic 78.3+/-7.3 versus monophasic 37.5+/-8.1%, P<0.01; 50 J: biphasic 65.5+/-11.5 versus monophasic 11.7+/-5.9%, P<0.01; 30 J: biphasic: 40.6+/-8.0 versus monophasic 3.1+/-3.1%, P<0.01). Within both waveforms, there were no significant differences in percent shock success at any energy level comparing baseline with LV dysfunction.</AbstractText>In this porcine model of acute LV dysfunction, biphasic waveform shocks were not only superior to monophasic waveform shocks for termination of VF during baseline, but retained superiority to monophasic waveform shocks when LV dysfunction was present.</AbstractText>
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3,580
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Analysing ventricular fibrillation ECG-signals and predicting defibrillation success during cardiopulmonary resuscitation employing N(alpha)-histograms.
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Mean fibrillation frequency may predict defibrillation success during cardiopulmonary resuscitation (CPR). N(alpha)-histogram analysis should be investigated as an alternative. After 4 min of cardiac arrest, and 3 versus 8 min of CPR, 25 pigs received either vasopressin or epinephrine (0.4, 0.4, and 0.8 U/kg vasopressin versus 45, 45, and 200 microg/kg epinephrine) every 5 min with defibrillation at 22 min. Before defibrillation, the N(alpha)-parameter histogramstart/histogramwidth and the mean fibrillation frequency in resuscitated versus non-resuscitated pigs were 2.9+/-0.4 versus 1.7+/-0.5 (P=0.0000005); and 9.5+/-1.7 versus 6.9+/-0.7 (P=0.0003). During the last minute prior to defibrillation, histogramstart/histogramwidth of > or =2.3 versus mean fibrillation frequency > or =8 Hz predicted successful defibrillation with subsequent return of a spontaneous circulation for more than 60 min with sensitivity, specificity, positive predictive value and negative predictive value of 94 versus 82%, 96 versus 89%, 98 versus 93% and 90 versus 74%, respectively. We conclude, that N(alpha)-analysis was superior to mean fibrillation frequency analysis during CPR in predicting defibrillation success, and distinction between vasopressin versus epinephrine effects.
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3,581
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Magnesium sulfate in the treatment of refractory ventricular fibrillation in the prehospital setting.
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To determine if magnesium sulfate (MgSO(4)) improves outcome in cardiac arrest patients initially in ventricular fibrillation (VF).</AbstractText>Randomized, prospective, double blind, placebo-controlled, multicenter prehospital trial using 2 g of MgSO(4). Eligible patients were non-traumatic cardiac arrest patients (> or =18 years of age) presenting in VF. The protocol included those patients refractory to three electroshocks. Epinephrine and either 2 g of MgSO(4) or placebo (normal saline) were then administered. The primary outcome variable was return of spontaneous circulation (ROSC) in the field and a perfusing pulse on arrival at the ED. Secondary endpoints included admission to the hospital (ADMT) and hospital discharge (DISC). IRB approval was obtained at all participating centers.</AbstractText>Total 116 patients (58 MgSO(4), 58 placebo) were enrolled during the period from 4/1992 to 10/96 with 109 available. There were no significant differences between the groups in baseline characteristics and times to cardio pulmonary resuscitation (CPR), advanced life support (ALS), and first defibrillation, except for time to study drug administration. There was no significant differences in ROSC (placebo, 18.5%, and MgSO(4), 25.5%, P=0.38), ADMT (placebo rate=16.7%, MgSO(4)=16.4%, P=1.0) or DISC (placebo rate=3.7%, MgSO(4)=3.6%, P=1.0).</AbstractText>We failed to demonstrate that the administration of 2 g of MgSO(4) to prehospital cardiac arrest patients presenting in VF improves short or long term survival.</AbstractText>
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3,582
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Optimal Response to Cardiac Arrest study: defibrillation waveform effects.
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Advances in early defibrillation access, key to the "Chain of Survival", will depend on innovations in defibrillation waveforms, because of their impact on device size and weight. This study compared standard monophasic waveform automatic external defibrillators (AEDs) to an innovative biphasic waveform AED.</AbstractText>Impedance-compensated biphasic truncated exponential (ICBTE) and either monophasic truncated exponential (MTE) or monophasic damped sine (MDS) AEDs were prospectively, randomly assigned by date in four emergency medical services. The study design compared ICBTE with MTE and MDS combined. This subset analysis distinguishes between the two classes of monophasic waveform, MTE and MDS, and compares their performance to each other and to the biphasic waveform, contingent on significant overall effects (ICBTE vs. MTE vs. MDS). Primary endpoint: Defibrillation efficacy with < or =3 shocks. Secondary endpoints: shock efficacy with < or =1 shock, < or =2 shocks, and survival to hospital admission and discharge. Observations included return of spontaneous circulation (ROSC), refibrillation, and time to first shock and to first successful shock.</AbstractText>Of 338 out-of-hospital cardiac arrests, 115 had a cardiac aetiology, presented with ventricular fibrillation, and were shocked by an AED. Defibrillation efficacy for the first "stack" of up to 3 shocks, for up to 2 shocks and for the first shock alone was superior for the ICBTE waveform than for either the MTE or the MDS waveform, while there was no difference between the efficacy of MTE and MDS. Time from the beginning of analysis by the AED to the first shock and to the first successful shock was also superior for the ICBTE devices compared to either the MTE or the MDS devices, while again there was no difference between the MTE and MDS devices. More ICBTE patients achieved ROSC pre-hospital than did MTE patients. While the rates of ROSC were identical for MTE and MDS patients, the difference between ICBTE and MDS was not significant. Rates of refibrillation and survival to hospital admission and discharge did not differ among the three populations.</AbstractText>ICBTE was superior to MTE and MDS in defibrillation efficacy and speed and to MTE in ROSC. MTE and MDS did not differ in efficacy. There were no differences among the waveforms in refibrillation or survival.</AbstractText>
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3,583
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Qualitative chaos analysis for ventricular tachycardia and fibrillation based on symbolic complexity.
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Ventricular fibrillation (VF) is one of the most serious malignant arrhythmias, usually resulting from immediate degeneration of ventricular tachycardia (VT). The surrogate data test (SDT) has been employed in the qualitative detection and analysis of cardiac chaos. Unfortunately, the current SDT method, based on the GP (Grassberger and Procaccia) algorithm, may not be suitable for the analysis of VF rhythm, which has been shown to be a high-dimensional signal. This paper proposes a novel qualitative analysis method based on symbolic dynamics for chaotic systems: the complexity dispersity method. Compared with the GP algorithm, our qualitative complexity method demonstrates better analytical accuracy and robustness and requires less data points (5 seconds vs 20 seconds). When used in the analysis of experimental data, our method achieved 100% accuracy in the detection of cardiac pathology for VT and VF.
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3,584
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Pediatric transthoracic defibrillation: biphasic versus monophasic waveforms in an experimental model.
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The purpose of this study was to determine and compare the efficacy of biphasic and monophasic waveforms in a porcine model of pediatric defibrillation.</AbstractText>The efficacy and safety of biphasic waveforms in children has not been established.</AbstractText>We initially studied 27 piglets: 12 weighed 3-6 kg ('infants'), and 15 weighed 7-12 kg ('children'). Ventricular fibrillation (VF) was induced by rapid right ventricular pacing and maintained for 15 s. Transthoracic shocks of 7-100 J energy were given using monophasic (5 ms truncated exponential) and biphasic (5 ms positive, 5 ms negative pulse, truncated exponential) waveforms. A second study of four 'infant' and four 'child' piglets utilized the same protocol but with a 10 ms instead of 5 ms monophasic truncated exponential shock waveform compared with the 10 ms biphasic waveform.</AbstractText>For both biphasic and monophasic waveforms, shock success rate (termination of VF) rose steadily as energy was increased. In the first study in the 'infant' 3-6 kg group, the 10 ms biphasic waveforms were superior to 5 ms monophasic waveforms at 10, 20, and 30 J energies, and in the 'child' 7-12 kg group at 20 and 30 J energies (P<0.05). High success rates (>80%) were achieved by 20 J (4 J/kg) biphasic waveform shocks in the 'infant' piglets and 30 J (3 J/kg) biphasic waveform shocks in the 'child' piglets. In the second study using a 10 ms monophasic waveform, we found similar results. Pulseless electrical activity occurred in two animals following biphasic shocks and in two animals following monophasic shocks.</AbstractText>Biphasic waveforms proved superior to monophasic waveforms in both infant and child models. High success rates were achieved with low-energy biphasic shocks. Biphasic waveform defibrillation is a promising advance in pediatric resuscitation.</AbstractText>
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3,585
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The beneficial effect of basic life support on ventricular fibrillation mean frequency and coronary perfusion pressure.
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Chest compressions before initial defibrillation attempts have been shown to increase successful defibrillation. This animal study was designed to assess whether ventricular fibrillation mean frequency after 90 s of basic life support cardiopulmonary resuscitation (CPR) may be used as an indicator of coronary perfusion and mean arterial pressure during CPR.</AbstractText>After 4 min of ventricular fibrillation cardiac arrest in a porcine model, CPR was performed manually for 3 min. Mean ventricular fibrillation frequency and amplitude, together with coronary perfusion and mean arterial pressure were measured before initiation of chest compressions, and after 90 s and 3 min of basic life support CPR. Increases in fibrillation mean frequency correlated with increases in coronary perfusion and mean arterial pressure after both 90 s (R=0.77, P<0.0001, n=30; R=0.75, P<0.0001, n=30, respectively) and 3 min (R=0.61, P<0.001, n=30; R=0.78, P<0.0001, n=30, respectively) of basic life support CPR. Increases in fibrillation mean amplitude correlated with increases in mean arterial pressure after both 90 s (R=0.46, P<0.01; n=30) and 3 min (R=0.42, P<0.05, n=30) of CPR. Correlation between fibrillation mean amplitude and coronary perfusion pressure was not significant both at 90 s and 3 min of CPR.</AbstractText>In this porcine laboratory model, 90 s and 3 min of CPR improved ventricular fibrillation mean frequency, which correlated positively with coronary perfusion pressure, and mean arterial pressure.</AbstractText>
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3,586
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Out of hospital cardiac arrests--the experience of one hospital in Singapore.
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In Singapore, all public emergency ambulances are equipped with semi-automatic external defibrillators and the crew is trained in their use. This is the first paper from Singapore reporting the survival rate in patients presenting to an urban public hospital with acute coronary syndrome (ACS) who developed out-of-hospital cardiac arrest (OHCA). All consecutive patients who presented to the ED of a public hospital with OHCA or ACS were surveyed from 1 April 1999 to 30 September 1999. There were 392 patients among whom 115 (28.5%) had OHCA. There was no significant difference in age and gender distribution between the OHCA and non-OHCA patients. More than 2/3 of the OHCA patients had no report of chest pain or breathlessness before they collapsed. Forty five (39.1%) of the 115 OHCA patients were noted to have initial rhythms of ventricular tachycardia (VT) or ventricular fibrillation (VF) and received pre-hospital defibrillation. The mean time from collapse to first DC shock was 12.07+/-7.2 min. Twenty (17.4%) of the OHCA patients had return of spontaneous circulation after resuscitation in the ED. Four patients (3.5%), all with an initial rhythm of VF were discharged alive from the hospital. Much remains to be done to reduce the time interval to first DC shock for the OHCA group.
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3,587
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Radiofrequency lesions produced by handheld temperature controlled probes for use in atrial fibrillation surgery.
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Detailed analysis of the size and shape of lesions produced by handheld radiofrequency ablation devices at open heart surgery has not been reported previously.</AbstractText>Radiofrequency lesions were made from the epicardial surface of the cardiac ventricles in open-chested dogs. The effects of electrode size, electrode temperature and duration of ablation were studied. In a second group of experiments simultaneous multielectrode ablation was performed on the ventricular epicardium after cold cardioplegia.</AbstractText>Using a single 12 x 2.5 mm electrode and a target temperature of 80 degrees C the lesion depth increased from 3.8+/-0.9 mm at 15 s, to 6.1+/-0.9 mm at 120 s (P=0.01). Increasing the target temperature from 70 to 90 degrees C (for 60 s) increased lesion depth from 5.0+/-1.2 to 5.6+/-1.7 mm (P=0.2). There was no difference in depth of lesions with the two electrode widths (4.0+/-0.5 mm (large) vs. 3.9+/-1.0 mm (small)). Lesions produced using the multielectrode probe (80 degrees C, 60 s) were 30-35 mm long with even penetration into the tissue. The mean depth of these lesions on microscopic sections was 3.9 mm. The mean width was 7.1 mm.</AbstractText>Handheld probes can be used to make deep linear lesions in the myocardium. Lesions expand rapidly and are wider than they are deep. A multielectrode ablation device allows rapid formation of linear lesions.</AbstractText>
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3,588
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To anticoagulate or not to anticoagulate patients with cardiomyopathy.
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The current published literature does not indicate whether the long-term effect of anticoagulant or antiplatelet therapy contributes to mortality reduction in patients with LV dysfunction. Evaluating patients for personal risk for emboli or for ischemic coronary artery events may influence the choice of therapies. As more is learned about the mechanisms of drug effects in different populations, physicians may be better able to direct appropriate therapies. Until that time, one must weigh the risks and benefits of each drug alone and in combination. In NYHA class IV patients, the risk for thrombosis owing to spontaneous clotting increases as does the adverse potential of warfarin and the adverse effects of inhibiting prostaglandin mediated vasodilation by aspirin. In NYHA class I and II patients, the quality of life and convenience of multidrug therapy is weighed against the devastating effect of a major stroke. In less symptomatic patients, the long-term risk for acute coronary events may be higher than previously identified. This would suggest that all patients with depressed LV function should be on some type of antiplatelet or anticoagulant therapy. The current WATCH study will provide much needed information about the outcome differences between these agents. Conclusions based on available data include the following: Heart failure is increasing in incidence and prevalence. Atherosclerotic disease is an important causative factor for the development of heart failure or may be a comorbid condition in these patients. There is a measurable rate of stroke in patients with heart failure, although the cause of death in large studies is more often owing to sudden death or progressive heart failure. Sudden death may be from new ischemic events, asystole, or from ventricular tachyarrhythmias. In patients with heart failure, not all strokes are cardioembolic in origin. The benefits and risks of warfarin may be increased as the EF worsens or heart failure functional class declines. The interactions of aspirin and ACE inhibitors have been best evaluated for the hemodynamic effects. There may be additional factors hitherto not studied. The hemodynamic effect of ACE inhibitors may be more important in NYHA classes III and IV than in less symptomatic patients. Warfarin use has clear indications for patients in atrial fibrillation with mechanical prosthetic valves, in hypercoagulable states, and with a previous history of embolization. Aspirin is inexpensive and commonly available, but its use must be evaluated and articulated by the prescribing physician. The current multicenter prospective trials will provide much needed guidance on this subject. The ongoing trials do not have a placebo arm, however, indicating a consensus among clinicians that patients with cardiomyopathy should be on an antiplatelet or anticoagulant drug until further data emerge.
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3,589
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Effects of angiotensin-converting enzyme inhibition on the development of the atrial fibrillation substrate in dogs with ventricular tachypacing-induced congestive heart failure.
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Atrial structural remodeling creates a substrate for atrial fibrillation (AF), but the underlying signal transduction mechanisms are unknown. This study assessed the effects of ACE inhibition on arrhythmogenic atrial remodeling and associated mitogen-activated protein kinase (MAPK) changes in a dog model of congestive heart failure (CHF).</AbstractText>Dogs were subjected to various durations of ventricular tachypacing (VTP, 220 to 240 bpm) in the presence or absence of oral enalapril 2 mg. kg(-1). d(-1). VTP for 5 weeks induced CHF, local atrial conduction slowing, and interstitial fibrosis and prolonged atrial burst pacing-induced AF. Atrial angiotensin II concentrations and MAPK expression were increased by tachypacing, with substantial changes in phosphorylated forms of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38-kinase. Enalapril significantly reduced tachypacing-induced changes in atrial angiotensin II concentrations and ERK expression. Enalapril also attenuated the effects of CHF on atrial conduction (conduction heterogeneity index reduced from 3.1+/-0.4 to 1.9+/-0.2 ms/mm, P<0.05), atrial fibrosis (from 11.9+/-1.1% to 7.5+/-0.4%, P<0.01), and mean AF duration (from 651+/-164 to 218+/-75 seconds, P<0.05). Vasodilator therapy of a separate group of VTP dogs with hydralazine and isosorbide mononitrate did not alter CHF-induced fibrosis or AF promotion.</AbstractText>CHF-induced increases in angiotensin II content and MAPK activation contribute to arrhythmogenic atrial structural remodeling. ACE inhibition interferes with signal transduction leading to the AF substrate in CHF and may represent a useful new component to AF therapy.</AbstractText>
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3,590
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Effects of melatonin on ischemia and reperfusion injury of the rat heart.
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Effects of melatonin on various manifestations of ischemia/reperfusion injury of the isolated perfused rat heart were examined. Ischemia- and reperfusion-induced ventricular arrhythmias were studied under constant flow in hearts subjected to 10, 15 or 25 min of regional ischemia (induced by LAD coronary artery occlusion) and 10-min reperfusion. Melatonin was added to the perfusion medium 5 min before ischemia at concentrations of 10 micromol/l or 10 nmol/l and was present throughout the experiment. Recovery of the contractile function was evaluated under constant perfusion pressure after 20-min global ischemia followed by 40-min reperfusion. Hearts were treated with melatonin at a high concentration (10 micromol/l) either 5 min before ischemia only (M1) or 5 min before ischemia and during reperfusion (M2) or only during reperfusion (M3). At the high concentration, melatonin significantly reduced the incidence of reperfusion-induced ventricular fibrillation and decreased arrhythmia score (10% and 2.2+/-0.3, respectively) as compared with the corresponding untreated group (62% and 4.1+/-0.3, respectively); the low concentration had no effect. This substance did not affect the incidence and severity of ischemic arrhythmias. Melatonin (M2, M3) significantly improved the recovery of the contractile function as compared with the untreated group; this protection did not appear if melatonin was absent in the medium during reperfusion (Ml). Our results show that melatonin, in accordance with its potent antioxidant properties, effectively protects the rat heart against injury associated with reperfusion. It appears unlikely that melatonin is cardioprotective at physiological concentrations.
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3,591
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Silymarin and vitamin E do not attenuate and vitamin E might even enhance the antiarrhythmic activity of amiodarone in a rat reperfusion arrhythmia model.
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Oxidative stress and lysosomal phospholipoidosis, which also might be partly attributed to free radicals induced by amiodarone (AM), may be involved in AM toxicity, which can be prevented by antioxidants. Our aim was to study if vitamin E (E) or silymarin (S), a lipid and a water-soluble antioxidant, modified the antiarrhythmic efficacy of AM in a rat reperfusion arrhythmia test. The following groups of male Sprague-Dawley rats (15 rats/group) were treated by gavage once a day for 4 weeks: 1. methylcellulose (MC, 0.4%), 2. sunflower seed oil (SSO), 3. AM, suspended in MC (30 mg/kg), 4. E, dissolved in SSO (100 mg/kg), 5. AM + E, 6. S, suspended in MC (80 mg/kg), 7. AM + S. The mean duration of ventricular tachycardia + fibrillation (MDVT + VF) and sinus rhythm (MDSR) the incidence of ventricular fibrillation (VF) and ventricular tachycardia (VT) and mortality were measured during a 10-min reperfusion after a 5-min coronary artery occlusion in anaesthetized rats. An arrhythmia score, representing the combined incidence and duration of different types of ventricular arrhythmia, was calculated. Compared with the MC group, MDSR was longer and MDVT + VF was shorter in all drug treated groups and in the SSO group. In the AM + E treated group MDSR was prolonged more and MDVT + VF was shortened more than in the AM, E or SSO groups. Compared with the MC group, the incidence of VF and mortality was similarly decreased in the SSO group and in most drug treated groups. No significant difference in the incidence of VT was found among all groups. The arrhythmia score was reduced by all drug treatments. Combined treatment with AM + E decreased arrhythmia score more than treatment with AM or SSO alone, but arrhythmia score was similar in the AM + E and E groups. In conclusion, both AM and antioxidant treatments alone or together resulted in a marked reduction of reperfusion arrhythmias in this model. SSO also exerted a moderate antiarrhythmic effect. Antioxidants administered together with AM did not attenuate and E might have even enhanced the antiarrhythmic effect of AM, therefore the combination of antioxidants with AM may be advantageous to reduce AM toxicity.
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3,592
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Heat stress protects against electrophysiological damages induced by acute doxorubicin exposure in isolated rat hearts.
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The use of anthracycline antibiotics as anticancer agents is limited by their cardiac toxicity. Heat stress (HS) is known to confer protection against various myocardial injuries such as ischemia-reperfusion induced damage. This cardioprotective mechanism is associated with an increase in endogenous antioxidative defenses and heat stress proteins (HSPs) synthesis. The aim of this study was thus to investigate whether HS could protect against acute doxorubicin cardiotoxicity using the isolated rat heart model. Rats were either heat stressed (42 degrees C for 15 min) or sham anesthetized. 24 h later, their hearts were isolated and retrogradely perfused at constant flow. Following 30-min of stabilization, hearts were perfused during 70 min with modified-Krebs solution containing 6 mg/l doxorubicin. Control hearts were perfused under identical conditions but without doxorubicin. Different hemodynamic and electrophysiological parameters were assessed in hearts from the four experimental groups. Doxorubicin exposure decreased left ventricular developed pressure (approximately -60% of baseline) and increased coronary perfusion pressure (approximately +230% of baseline). Prior HS did not modify these effects. Incidence of ventricular fibrillation (VF) was significantly enhanced by doxorubicin exposure (66% vs 0% in control group). Moreover, the ventricular action potential duration (APD) was significantly shortened in the presence of doxorubicin. Prior HS prevented both increase in VF incidence and shortening of APD. We conclude that prior heat stress protects myocardium against electrophysiological injury, but not against hemodynamic damage, induced by acute doxorubicine exposure. Further investigations are required to elucidate the precise mechanisms involved in this effect.
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3,593
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Transtracheal oxygenation : an alternative to endotracheal intubation during cardiac arrest.
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Because efforts to secure adequate arterial oxygenation during cardiac resuscitation are more important than efforts to promote CO(2) elimination, we investigated whether continuous transtracheal oxygenation (TTO) could represent a potentially simpler alternative to conventional positive-pressure ventilation with 100% O(2) through an endotracheal tube.</AbstractText>Controlled and randomized.</AbstractText>Animal laboratory.</AbstractText>Thirty male Sprague-Dawley rats.</AbstractText>The technique for TTO was initially developed and tested in five rats. A model of ventricular fibrillation (VF) was then used to compare the effects of TTO (n = 5) with the effects of O(2) delivery through an endotracheal tube as part of positive-pressure ventilation (n = 5) or through a mask without additional airway intervention (n = 5). VF was induced and left untreated for 4 min, after which chest compression and one of the three oxygenation interventions was started. Defibrillation was attempted after 6 min of chest compression. In a subsequent series, defibrillation was attempted after 10 min of chest compression in rats treated with either TTO (n = 5) or endotracheal intubation (ET; n = 5).</AbstractText>TTO and ET secured adequate arterial PO(2) during chest compression (213 +/- 77 mm Hg and 154 +/- 36 mm Hg; not significant), whereas the mask yielded an arterial PO(2) of only 49 +/- 38 mm Hg (p < 0.05). Each rat treated with TTO or ET was successfully resuscitated and survived the postresuscitation interval, but none of the rats treated with the mask survived. TTO maintained its efficacy after increased duration of chest compression.</AbstractText>TTO was as effective as conventional positive-pressure ventilation with 100% O(2) for securing oxygenation, resuscitation, and short-term survival and more effective than O(2) delivered through a mask.</AbstractText>
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3,594
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[Diastolic heart failure. Treatment].
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Many therapeutic options are proposed for the treatment of diastolic heart failure although no consensus has been established. In experimental trials, several drugs have demonstrated a potentially beneficial effect on ventricular diastolic dysfunction and could be used for diastolic heart failure: nitrate derivatives, converting enzyme inhibitors, angiotensin II antagonists, spirolactones and bradycardia agents. CLINICAL PRACTICE: In everyday clinical practice, low-dose diuretics and treatments aimed at reducing the triggering factor leading to episodes of heart failure are used alone or in combination with treatments aimed at the underlying cause of the diastolic dysfunction: betablockers, calcium inhibitors or nitrate derivatives for ischemic heart disease, drug therapy for hypertension, anti-diabetes agents, anti-arrhythmic agents for atrial fibrillation. Digitalics are not indicated. In experimental trials, converting enzyme inhibitors and angiotensin II antagonists have demonstrated interesting properties for the left ventricle but to date are not warranted for diastolic heart failure. TREATMENT OF THE CAUSE: Due to the lack of consensus on the optimal treatment for diastolic heart failure, most clinicians rely on treating the underlying heart disease and triggering factors.
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3,595
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[When is surgery needed for minimally symptomatic or asymptomatic acquired valvulopathy?].
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GENERAL PRINCIPLES: The first step is to determine the absence or the minimal nature of the functional impairment from history taking and, for doubtful cases, with an exercise test. Therapeutic indications differ depending on the valvular lesion. AORTIC STENOSIS: Surgery is indicated only for severe aortic stenosis or in cases with a particular risk. Indications for surgery are: false asymptomatic patients with a positive exercise test, patients with abnormal hemodynamic and/or rhythm response to an exercise test (decrease in systolic pressure > 10 mmHg, severe ventricular arrhythmia), aortic stenosis with left ventricular ejection fraction < 50%, aortic stenosis associated with severe coronary artery disease amendable with bypass surgery. MITRAL STENOSIS: The advent of percutaneous mitral commissurotomy has totally changed the treatment of mitral stenosis. This new method can be proposed for stenotic but flexible mitral valves with no major lesion of the lower valvular apparatus or for more advanced valve disease with a risk of hemodynamic failure or thromboembolism. MITRAL INSUFFICIENCY: When mitral leakage is the only valvular defect, surgery is indicated if the volume regurgitated is important as assessed clinically and by echocardiography. Conservative surgery is preferred due to the low risk and the high probability of good long term outcome. Factors to take into account include: the experience of the surgical team in this field, the etiology of mitral insufficiency, the impact on the cardiac condition. Surgery should be performed before the development of atrial fibrillation, major cardiomegaly, left ventricular dilatation (end systolic diameter > 45 mm), or an alteration of the ejection fraction (< 60%). AORTIC INSUFFICIENCY: Cases of the aortic insufficiency should be differentiated according to the state of the ascending aorta. Annuloaortic ectasia requires surgery when the diameter reaches = 50-55 mm (depending on the authors). For valve dysplasia with non aneurysmal cylindrical dilatation of the ascending aorta, the indication for surgery depends on the progressive aggravation of the aortic dilatation. For cases with unique valve lesions, the indication for surgical repair of aortic insufficiency depends on the impact on the left ventricle. Indications for surgery include major radiographic cardiomegaly (cardio-thoracic ratio > 0.58), echocardiographic evidence of major left ventricular dilatation (end diastolic diameter > 75 mm and end systolic diameter > 55 mm), or an alteration of the systolic function (ejection fraction < 0.50 or 0.55). SPECIAL SITUATIONS: In disease states associating stenosis and insufficiency, valve replacement is often the only possibility. Careful patient selection is the rule. Surgery is often needed for cases with multiple valve involvement where different therapeutic options can be used for the different valves. The dominant lesion and the degree of heart dilatation and dysfunction guide decision making.
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3,596
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Blocking Na(+)/H(+) exchange reduces [Na(+)](i) and [Ca(2+)](i) load after ischemia and improves function in intact hearts.
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We determined in intact hearts whether inhibition of Na(+)/H(+) exchange (NHE) decreases intracellular Na(+) and Ca(2+) during ischemia and reperfusion, improves function during reperfusion, and reduces infarct size. Guinea pig isolated hearts were perfused with Krebs-Ringer solution at 37 degrees C. Left ventricular (LV) free wall intracellular Na(+) concentration ([Na(+)](i)) and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured using fluorescence dyes. Hearts were exposed to 30 min of ischemia with or without 10 microM of benzamide (BIIB-513), a selective NHE-1 inhibitor, infused for 10 min just before ischemia or for 10 min immediately on reperfusion. At 2 min of reperfusion, BIIB-513 given before ischemia decreased peak increases in [Na(+)](i) and [Ca(2+)](i), respectively, from 2.5 and 2.3 times (controls) to 1.6 and 1.3 times pre-ischemia values. At 30 min of reperfusion, BIIB-513 increased systolic-diastolic LV pressure (LVP) from 49 +/- 2% (controls) to 80 +/- 2% of pre-ischemia values. BIIB-513 reduced ventricular fibrillation by 54% and reduced infarct size from 64 +/- 1% to 20 +/- 3%. First derivative of the LVP, O(2) consumption, and cardiac efficiency were also improved by BIIB-513. Similar results were obtained with BIIB-513 given on reperfusion. These data show that Na(+) loading is a marker of reperfusion injury in intact hearts in that inhibiting NHE reduces Na(+) and Ca(2+) loading during reperfusion while improving function. These results clearly implicate the ionic basis by which inhibiting NHE protects the guinea pig intact heart from ischemia-reperfusion injury.
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3,597
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Arrhythmogenic ionic remodeling: adaptive responses with maladaptive consequences.
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Compensatory changes in ion transport mechanisms occur in response to a variety of cardiac disease processes. Recent work has demonstrated that these adaptive responses can produce the arrhythmogenic substrate for a variety of important cardiac rhythm disorders. Two important paradigms are atrial tachycardia-induced remodeling and ionic remodeling caused by congestive heart failure. Atrial tachycardia promotes cellular Ca(2)+ loading and downregulates a variety of ion channels, particularly L-type Ca(2)+ channels, thereby promoting the occurrence and maintenance of atrial fibrillation. Congestive heart failure alters the expression and function of a variety of membrane transport processes, including several K(+)-channels and key Ca(2)+-transport systems, favoring the occurrence of arrhythmogenic afterdepolarizations. An improved understanding of the mechanisms and consequences of arrhythmogenic ionic remodeling promises to lead to novel and improved therapeutic approaches.
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3,598
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[Severe ibutilide-induced arrhythmia in patients with heart failure].
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Ibutilide is a novel class III antiarrhythmic agent used for the termination of atrial flutter and atrial fibrillation. It mainly affects membrane potassium currents (IKr) and prolongs the cardiac action potential. This effect is reflected as QT-interval prolongation in the ECG. Drugs that affect IKr-currents are known to cause malignant ventricular arrhythmia.</AbstractText>We report three patients with heart failure where ibutilide triggered malignant ventricular arrhythmias (sustained torsades de pointes).</AbstractText>All patients experienced dramatic haemodynamic deterioration. One patient died because of sustained arrhythmia. Mode of action for ibutilide is described. Precautions that should be observed when using ibutilide are outlined.</AbstractText>Ibutilide is contraindicated in patients with heart failure and should be used with caution in patients with ischaemic heart disease or previous myocardial infarction. Ibutilide-induced ventricular arrhythmias may be particularly difficult to treat in patients with heart failure.</AbstractText>
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3,599
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Adverse hemodynamic effects of interrupting chest compressions for rescue breathing during cardiopulmonary resuscitation for ventricular fibrillation cardiac arrest.
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Despite improving arterial oxygen saturation and pH, bystander cardiopulmonary resuscitation (CPR) with chest compressions plus rescue breathing (CC+RB) has not improved survival from ventricular fibrillation (VF) compared with chest compressions alone (CC) in numerous animal models and 2 clinical investigations.</AbstractText>After 3 minutes of untreated VF, 14 swine (32+/-1 kg) were randomly assigned to receive CC+RB or CC for 12 minutes, followed by advanced cardiac life support. All 14 animals survived 24 hours, 13 with good neurological outcome. For the CC+RB group, the aortic relaxation pressures routinely decreased during the 2 rescue breaths. Therefore, the mean coronary perfusion pressure of the first 2 compressions in each compression cycle was lower than those of the final 2 compressions (14+/-1 versus 21+/-2 mm Hg, P<0.001). During each minute of CPR, the number of chest compressions was also lower in the CC+RB group (62+/-1 versus 92+/-1 compressions, P<0.001). Consequently, the integrated coronary perfusion pressure was lower with CC+RB during each minute of CPR (P<0.05 for the first 8 minutes). Moreover, at 2 to 5 minutes of CPR, the median left ventricular blood flow by fluorescent microsphere technique was 60 mL. 100 g(-1). min(-1) with CC+RB versus 96 mL. 100 g(-1). min(-1) with CC, P<0.05. Because the arterial oxygen saturation was higher with CC+RB, the left ventricular myocardial oxygen delivery did not differ.</AbstractText>Interrupting chest compressions for rescue breathing can adversely affect hemodynamics during CPR for VF.</AbstractText>
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