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8,500 | Ventricular fibrillation induced by a radiofrequency energy delivery for idiopathic right ventricular outflow tachycardia. | We report a case of a patient with idiopathic right ventricular tachycardia who underwent radiofrequency (RF) catheter ablation. Shortly after the delivery of the RF energy, a nonsustained VT cluster occurred, and eventually resulted in VF, requiring cessation of the RF delivery and a 200 J transthoracic external cardioversion delivery. |
8,501 | Low-dose carvedilol reduces transmural heterogeneity of ventricular repolarization in congestive heart failure. | To study the effects of carvedilol on the transmural heterogeneity of ventricular repolarization in rabbits with congestive heart failure (CHF).</AbstractText>Rabbits were randomly divided into 3 groups: control, CHF and carvedilol treated CHF group. Monophasic action potential duration (MAPD) in the 3 myocardial layers was simultaneously recorded.</AbstractText>All the rabbits in the CHF group had signs of severe CHF. Compared with the control group, the mean blood pressure and cardiac output were significantly decreased, while peripheral resistance was significantly increased in the CHF group. This proved that the CHF model was successful created with adriamycin in this study. Compared to the control group, the ventricular fibrillation threshold (VFT) was remarkably decreased and all MAPD of the 3 myocardial layers were extended in rabbits with CHF. However, the extension of MAPD in the midmyocardium was more obvious. The transmural dispersion of repolarization (TDR) was significantly increased in CHF. Low-dose carvedilol (0.25 mg/kg, twice daily) had no effects on ventricular remodeling. Treatment with low-dose carvedilol significantly increased VFT. Although the MAPD of the 3 myocardial layers were further prolonged in the carvedilol treated CHF group, the prolongation of MAPD in the midmyocardium was shorter than those in the epicardium and endocardium. Treatment with low-dose carvedilol significantly decreased TDR in CHF.</AbstractText>In the present study, the transmural heterogeneity of ventricular repolarization increased in the rabbits with CHF. Low-dose carvedilol decreased the transmural heterogeneity of ventricular repolarization in CHF, which may be related to its direct electrophysiological property rather than its effect on ventricular remodeling.</AbstractText> |
8,502 | Cardiopulmonary arrest and resuscitation in Landrace/Large White swine: a research model. | Sudden cardiac death (SCD) is a field of continuous research. In order to answer various questions regarding SCD, several animal models have been developed. The aim of the present study is to describe our experimental model of inducing cardiac arrest in Landrace/Large White pigs, and then resuscitated according to the International Guidelines on resuscitation. Fifteen Landrace/Large White pigs were anaesthetized and intubated while spontaneously breathing. The left and right jugular veins, as well as the femoral and the carotid arteries, were surgically prepared. Induction of cardiac arrest was achieved by using an ordinary rechargeable lithium battery, through a pacemaker wire inserted into the right ventricle. The typical Advanced Life Support (ALS) protocol was followed, and in case of restoration of spontaneous circulation, the animals were further evaluated for 30 min. Seven animals were successfully resuscitated using this protocol, whereas eight failed resuscitation efforts. Successful resuscitation was contingent on the restoration of the levels of coronary perfusion pressure and PETCO(2) during chest compressions. Among the different ways of inducing cardiac arrest, the ordinary lithium battery is a simple, safe and valuable technique. Landrace/Large White pigs' baseline haemodynamics closely resemble human haemodynamics, making the breed a favourable model for resuscitation. |
8,503 | Repolarization variability in the risk stratification of MADIT II patients. | QT variability has been reported to be associated with ventricular arrhythmias and sudden cardiac death. There is limited data regarding variability in T-wave morphology and its prognostic value. In this study, we present a novel approach for the measurement of T-wave variability (TWV) reflecting changes in T-wave morphology, and we investigate the prognostic significance of Holter-derived TWV in patients with and without ventricular arrhythmias requiring appropriate implantable cardioverter defibrillator (ICD) therapy from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II). Methods Study population consisted of 275 ICD patients from MADIT II after excluding patients with intraventricular conduction abnormalities or atrial fibrillation. TWV was measured based on amplitude variance of T-wave amplitude. Results During 2-year follow-up, 58 (21%) patients had appropriate ICD therapy for ventricular tachycardia or fibrillation. Patients with appropriate ICD therapy had higher levels of TWV measures than those without arrhythmic events. After adjustment for heart rate, ejection fraction, and significant clinical predictors of arrhythmic events, a Cox proportional-hazards regression model revealed that dichotomized TWV values were predictive for ventricular tachyarrhythmias requiring appropriate ICD therapy (hazard ratio, 2.0; 95% CI; 1.2-3.5; P=0.01). On the basis of the comprehensive testing, TWV value >59 microV was found predictive for arrhythmic events in MADIT II population.</AbstractText>Our newly designed method for the assessment of repolarization variability in ambulatory Holter recordings detected transient variability of T-wave morphology, which was predictive for ventricular tachyarrhythmias in the MADIT II population.</AbstractText> |
8,504 | Delayed termination of ventricular tachycardia after cardioversion. | Both anti-tachycardia pacing and cardioversion via an implantable cardioverter defibrillator are effective therapies for ventricular tachycardia (VT). We report a case of VT where cardioversion resulted in delayed termination of tachycardia. Potential mechanisms for this observation are discussed. |
8,505 | Limited cardiotoxicity after extensive thoracic surgery and intraoperative hyperthermic intrathoracic chemotherapy with doxorubicin and cisplatin. | Recently, pleural mesothelioma has been treated by cytoreductive surgery and intraoperative hyperthermic intrathoracic chemotherapy with doxorubicin and cisplatin. The well-established cardiotoxicity of doxorubicin and distressing data from an animal study raised concern about its impact on cardiac function. In the present study, early cardiotoxicity of this treatment modality was prospectively analyzed.</AbstractText>In 13 pleural mesothelioma patients, cardiotoxicity was monitored by clinical examination, electrocardiography, Troponin levels, cardiac ultrasonography, and estimation of left ventricular ejection fraction (LVEF) by radionuclide ventriculography before and during the first 6 months after cytoreductive surgery and intraoperative hyperthermic intrathoracic chemotherapy with doxorubicin (25-54 mg/m(2)) and cisplatin (65-120 mg/m(2)).</AbstractText>No clinical cardiac failure or treatment-related death was observed. In two patients transient atrial fibrillation was noted; one associated with pulmonary emboli. Early posttreatment Troponin release was not of predictive value. Ultrasonography did not reveal significant alterations. LVEF decreased significantly (mean 0.07 or 11%, P = .001) during the first 3 months and remained stable thereafter. In univariate analysis, the degree of LVEF reduction was statistically related to maximal intrathoracic doxorubicin concentration (P = .031) and total cisplatin dose (P = .029). Direct exposure of the heart to the drugs as a result of partial pericardectomy was not associated with greater LVEF decrease. On the contrary, partial pericardectomy seemed to be associated with a smaller LVEF decline than when the pericardium remained intact (P = .045). In this small series, no statistically significant correlation between other treatment or pharmacokinetic parameters and LVEF decline was found. Notably, higher doxorubicin plasma concentrations and exposure were not associated with increased LVEF reduction.</AbstractText>Early cardiotoxicity is limited after this treatment modality using substantial doses of doxorubicin and cisplatin. Hence, this study suggests that intrathoracic chemotherapy with doxorubicin and/or cisplatin may be used for primary and secondary pleural malignancies, even immediately after extensive thoracic surgery, without concern of severe early cardiotoxicity.</AbstractText> |
8,506 | Comparison of conduction delay in the right ventricular outflow tract between Brugada syndrome and right ventricular cardiomyopathy: investigation of signal average ECG in the precordial leads. | In both Brugada syndrome (BS) and arrhythmogenic right ventricular cardiomyopathy (ARVC), electrical abnormalities in the right ventricular outflow tract (RVOT) are important for arrhythmogenesis.</AbstractText>The aim of this study was to compare conduction delay in the right ventricular in BS with that in ARVC using the signal-averaged electrocardiogram.</AbstractText>Twenty patients with BS (18 men and 2 women; 55 +/- 12 years old; 9 symptomatic and 11 asymptomatic) and eight patients with ARVC (six men and two women; 53 +/- 16 years old) were included. We assessed the presence of late potentials (LPs) and the filtered QRS duration (fQRSd) in V(2) and V(5) using a high-pass filter of 40 Hz (fQRSd:40) and 100 Hz (fQRSd:100).</AbstractText>In ARVC, there was no significant difference in fQRSd:40 between V2 and V5 (158 +/- 19 vs. 145 +/- 17 ms, respectively): however, in BS, fQRSd:40 in V2 was significantly longer than fQRSd:40 in V5 (147 +/- 15 vs. 125 +/- 10 ms, P < 0.001). In ARVC, there was no significant difference between fQRSd:40 and fQRSd:100 in V(2) and V(5) (158 +/- 19 vs. 142 +/- 23 ms and 145 +/- 17 vs. 132 +/- 9 ms, respectively). In contrast, in BS, fQRSd:100 was significantly shorter than fQRSd:40 in V2 (110 +/- 8 ms vs. 147 +/- 15, P < 0.001). The relative decrease in fQRSd:100 compared with fQRSd:40 in V2 was significantly greater in BS than in ARVC.</AbstractText>The dominant prolongation of the fQRSd in the right precordial lead in BS was different from the characteristics of ARVC, which may be caused by the conduction delay due to fibro-fatty replacement in RV.</AbstractText> |
8,507 | Efficacy of cardiac resynchronization therapy in very old patients: the Insync/Insync ICD Italian Registry. | To assess the effects of cardiac resynchronization therapy (CRT) in > or =80-year-old patients vs. patients <80 years, in terms of clinical, functional, and echocardiographic parameters after 12 month of CRT, survival, and incidence of arrhythmic events.</AbstractText>The study population consisted of 1181 CRT patients (85 were > or =80 years old). They were enrolled in a national observational registry and underwent baseline evaluation and periodical follow-up visits. In the overall population, New York Heart Association class and ejection fraction (EF) improved and ventricular diameters decreased. Similar changes were observed in the two groups. In the study population, 157 patients died, 144 (13%) in the <80 years group and 13 (15%) in the > or =80 years group. There was a higher all-cause mortality (log-rank test, P = 0.015) among > or =80 years patients, with a trend towards higher sudden cardiac death (SCD) (P = 0.057), but similar non-SCD (P = 0.293). Using the combined endpoint of SCD or appropriate shock from a defibrillator for ventricular fibrillation, no significant differences resulted between groups (P = 0.455). In both groups, lower EF was associated with higher mortality.</AbstractText>Cardiac resynchronization therapy demonstrated similar efficacy in patients aged > or =80 years and in those under 80, in terms of clinical and functional parameters and reverse remodelling. Similarly, CRT resulted in comparable effects on death for heart failure and on SCD.</AbstractText> |
8,508 | [Treatment of atrial fibrillation]. | Atrial fibrillation is a common and in most patients recurrent arrhythmia. Atrial fibrillation can increase mortality and causes at times severe symptoms in affected patients. Timely initiation of sustained oral anticoagulation is indicated in patients with atrial fibrillation at risk for stroke to prevent thromboembolic complications. Patients at risk for stroke can be identified by clinical characteristics using validated score systems, e.g., the CHADS(2) score or the Framingham score. Drugs that slow AV nodal conduction can improve symptoms associated with high ventricular rate. Cardioversion can acutely terminate atrial fibrillation in almost all patients, but many patients suffer from recurrent atrial fibrillation. The prevention of arrhythmia recurrences ("rhythm control therapy") is indicated in patients with severe arrhythmia-related symptoms. Antiarrhythmic drugs can approximately double the maintenance rate of sinus rhythm. Other drugs that were not primarily developed as antiarrhythmic agents, e.g., ACE inhibitors, sartans, and possibly statins, can further improve maintenance of sinus rhythm in selected patient groups. Catheter-based isolation of the pulmonary veins is a recently developed intervention that can cure some forms of atrial fibrillation. It is likely that a multimodal therapeutic approach will in the future allow rhythm control therapy to become more effective. |
8,509 | Electrical atrial fibrillation induction affects the characteristics of induced arrhythmia. | Several methods are being used to induce atrial fibrillation (AF) in experimental investigations, which may affect the electrophysiologic parameters of the induced arrhythmia. The aim of our study was the investigation of temporal characteristics of AF during and after electrical induction. Direct current and high-frequency stimulation was used for induction in bipolar biatrial, right and left atrial appendage configurations in 6 dogs. Atrial and ventricular electrical activity was recorded near the bundle of His. Seven statistical parameters were calculated to analyze the temporal characteristics of electrical activity of both chambers. The induction method affected 5 atrial and no ventricular electrophysiologic parameters during stimulation, and the effect disappeared after ceasing induction, during the induced transient or persistent AF. Electrical stimulation affects the properties of the induced arrhythmia during the induction; thus, the investigation of AF is recommended only after ceasing the induction to avoid bias. |
8,510 | Ventricular repolarization dynamicity provides independent prognostic information toward major arrhythmic events in patients with idiopathic dilated cardiomyopathy. | The purpose of this work was to evaluate whether ventricular repolarization dynamicity predicts major arrhythmic events in patients with idiopathic dilated cardiomyopathy (DCM).</AbstractText>Arrhythmic risk stratification in patients with DCM is still an open issue. Ventricular repolarization analysis should provide relevant information, but QT interval and QT dispersion failed in predicting arrhythmic risk.</AbstractText>The following parameters were evaluated in 179 consecutive DCM patients without history of sustained ventricular tachycardia (VT) and/or ventricular fibrillation (VF) at enrollment: QRS duration, QT interval corrected for heart rate, and QT dispersion at electrocardiogram (ECG); left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter at echocardiogram; and nonsustained ventricular tachycardia (NSVT), heart rate variability (standard deviation of RR intervals), and ventricular repolarization dynamicity as measured by means of 24-h ECG monitoring, by calculating the slope of linear regression analysis of QT end and RR intervals (QTe-slope) and the value of mean QT end corrected for heart rate.</AbstractText>During a mean follow-up of 39 months, 9 patients died suddenly and 15 experienced VT and/or VF. At multivariate analysis, LVEF (p = 0.047), NSVT (p = 0.022), and QTe-slope (p = 0.034) were significantly associated with arrhythmic events. Among the patients with a low LVEF, NSVT and/or steeper QTe-slope identified a subgroup at highest arrhythmic risk.</AbstractText>In patients with DCM, QT dynamicity is independently associated with the occurrence of major arrhythmic events and improves the predictive accuracy of stratifying arrhythmic risk of these patients.</AbstractText> |
8,511 | Burden of atrial fibrillation after cardiac resynchronization therapy. | Cardiac resynchronization therapy (CRT) may diminish atrial fibrillation (AF) burden in patients with chronic heart failure (HF). Each of 27 patients without permanent AF in whom CRT implantation was unsuccessful was paired with 2 active CRT patients-1 responder and 1 nonresponder-based on age, gender, cause of HF, and history of paroxysmal AF. Device-documented high atrial rates and mode-switching episodes were tabulated during a median follow-up of 386 days. CRT responders had significantly improved left ventricular (LV) ejection fraction and New York Heart Association functional class compared with nonresponders and controls. Left atrial dimension change was similar among the groups (+0.03 +/- 0.92 cm controls; -0.18 +/- 0.80 cm responders; -0.11 +/- 1.01 cm nonresponders) despite a significant reduction in mitral regurgitation in responders compared with nonresponders. There was no significant difference in AF burden between controls and patients who underewent CRT when indexed over time. Median AF-free follow-up was significantly longer in patients who underwent CRT without a history of AF (log-rank p = 0.04), but no differences were seen in the overall cohorts. In conclusion, despite inducing LV reverse remodeling and clinical improvement, CRT does not appear to decrease AF burden in responders compared with nonresponders or matched controls in whom CRT implantation failed. CRT may, however, delay onset of new AF. |
8,512 | Comparison of rate versus rhythm control for atrial fibrillation in patients with left ventricular dysfunction (from the AFFIRM Study). | Optimal treatment for patients with atrial fibrillation (AF) and left ventricular (LV) dysfunction is not well defined. It is unclear if sinus rhythm is of greater benefit in patients with significantly reduced ejection fraction (EF) than in patients with normal or mildly depressed LV function. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study compared 2 treatment strategies: "rhythm control," attempting to maintain sinus rhythm, principally with antiarrhythmic drugs, and "rate control," allowing AF to persist or recur while controlling the ventricular rate. We sought to determine if rhythm control was superior to rate control for patients in the AFFIRM study with various degrees of LV dysfunction. The present study analyzed outcome data of 3,032 subjects from the AFFIRM study with LV dysfunction by 3 EF strata: 40% to 49%, 30% to 39%, and <30%. The end points were mortality, hospitalization, and a change in New York Heart Association (NYHA) class. Analyses were done by intent to treat and by final rhythm status. In conclusion, there was no significant improvement in mortality, hospitalization, and NYHA class with the strategy of rhythm control in any of the 3 EF strata. When the data were analyzed by final rhythm status, we again found no significant benefit to patients in the rhythm control arm. |
8,513 | Comparison of defibrillation efficacy and survival associated with right versus left pectoral placement for implantable defibrillators. | The preferred location for an implantable cardioverter-defibrillator (ICD) generator is the left pectoral region as a result of the shock vector formed by the active can and the lead system. However, a right pectoral site is necessary when left-sided implantation is contraindicated. The Low Energy Safety Study was a prospective, randomized trial conducted to assess chronic defibrillation efficacy in 627 patients, including 37 (5.9%) who received right pectoral implants and 590 (94.1%) who received left pectoral implants. Patients were followed for a mean of 24 +/- 13 months. There were no significant differences observed between patients who received left versus right pectoral implants in age, gender, indications, New York Heart Association classification, or ejection fraction. Patients who received a right pectoral implant had higher defibrillation thresholds at implantation (10.6 +/- 3.8 J) than those who received a left pectoral implant (8.9 +/- 4.2 J, p = 0.01) despite similar shock impedances. The conversion efficacy for spontaneous arrhythmia episodes among patients who received right and left pectoral implants were not significantly different (33 of 33 [100%] vs 255 of 263 [97%], respectively; p = 0.31). In addition, the conversion efficacy for induced ventricular fibrillation episodes were also similar (187 of 188 [99%] on the right vs 2429 of 2475 [98%] on the left, p = 0.18). However, the all-cause mortality rate was higher for patients who received right-sided implants (hazard ratio 1.93, p <0.004). In conclusion, defibrillation thresholds are higher with right pectoral implants compared with left-sided implants, but with a proper energy safety margin, there are no significant differences in spontaneous or induced shock conversion efficacy. However, the near doubling of the mortality rate among patients with right-sided implants needs to be considered when recommending such device therapy. |
8,514 | Age and follow-up time affect the prognostic value of the ECG and conventional cardiovascular risk factors for stroke in adult men. | To explore whether the predictive power of mid-life ECG abnormalities and conventional cardiovascular risk factors for future stroke change over a 30-year follow-up period, and whether a repeated examination improves their predictive power.</AbstractText>Longitudinal population-based study.</AbstractText>2,322 men aged 50 years, with a follow-up period of 30 years. 1,221 subjects were re-examined at age 70 years</AbstractText>Risk for fatal and non-fatal stroke during three decades of follow-up. Investigations included resting ECG and traditional cardiovascular risk factors.</AbstractText>When measured at age 50 years, ST segment depression and T wave abnormalities, together with ECG-left ventricular hypertrophy, were of importance only during the first 20 years, but regained importance when re-measured at age 70 years. Blood pressure was a significant predictor for stroke over all three decades of follow-up. In elderly people only, there is evidence that apolipoprotein A1 may protect from future stroke.</AbstractText>Mid-life values for blood pressure and ECG abnormalities retain their predictive value over long follow-up periods even though they improved in predictive power when re-measured in elderly people. Despite lower prevalence, ECG abnormalities had greater impact at age 50 years than at age 70 years. By contrast, apolipoprotein A1 was protective for future stroke only at age 70 years.</AbstractText> |
8,515 | Sustained abdominal compression during CPR raises coronary perfusion pressures as much as vasopressor drugs. | This study investigated sustained abdominal compression as a means to improve coronary perfusion pressure (CPP) during cardiopulmonary resuscitation (CPR) and compared the resulting CPP augmentation with that achieved using vasopressor drugs.</AbstractText>During electrically induced ventricular fibrillation in anesthetized, 30kg juvenile pigs, Thumper CPR was supplemented at intervals either by constant abdominal compression at 100-500mmHg using an inflated contoured cuff or by the administration of vasopressor drugs (epinephrine, vasopressin, or glibenclamide). CPP before and after cuff inflation or drug administration was the end point.</AbstractText>Sustained abdominal compression at >200mmHg increases CPP during VF and otherwise standard CPR by 8-18mmHg. The effect persists over practical ranges of chest compression force and duty cycle and is similar to that achieved with vasopressor drugs. Constant abdominal compression also augments CPP after prior administration of epinephrine or vasopressin.</AbstractText>During CPR noninvasive abdominal compression with the inflatable contoured cuff rapidly elevates the CPP, sustains the elevated CPP as long as the device is inflated, and is immediately and controllably reversible upon device deflation. Physical control of peripheral vascular resistance during CPR by abdominal compression has some advantages over pharmacological manipulation and deserves serious reconsideration, now that the limitations of pressor drugs during CPR have become better understood, including post-resuscitation myocardial depression and the need for intravenous access.</AbstractText> |
8,516 | The effect of ischemia on ventricular fibrillation as measured by fractal dimension and frequency measures. | Most animal studies of ventricular fibrillation (VF) waveform characteristics involve healthy animals with VF initiated by electric shock. However, clinical VF is usually the result of ischemia. The waveform characteristics in these two types of VF may differ. The angular velocity (AV), frequency ratio (FR) and median frequency (MF) are three frequency-based measures of VF. The scaling exponent (ScE), the logarithm of the absolute correlations (LAC) and the Hurst exponent (HE) are three measures of the fractal dimension of VF.</AbstractText>We hypothesized that these quantitative measures would differ between ischemic and electrically initiated VF.</AbstractText>VF was induced in 14 swine by electric shock and in 12 swine by ischemia. For ischemia induced VF animals, an angioplasty catheter was positioned in the mid-LAD and the balloon inflated. A mean of 891+/-608 (S.D.)s later, VF occurred. For electrically induced animals, an AC current was passed through a catheter in the RV. Following initiation by either method, VF was recorded for 7min. Sequential 5s epochs were analyzed for AV, FR, MF and fractal dimension measures.</AbstractText>Ischemic VF demonstrated a significantly higher fractal dimension as estimated by the ScE for the first 0-90s (p=0.021) and for 90-180s (p=0.016). The Hurst exponent was significantly higher for ischemic VF for both 0-90s (p<0.0001) and 90-180s (p<0.0001). The fractal dimension as estimated by the LAC method was not significantly different for 0-90s (p=0.056) but was highly significant for 90-180s (p=0.001). During the initial 90s the groups did differ in all measures of frequency as follows: AV (p<0.001), FR (p<0.001), MF (p<0.001). These differences did not persist beyond 90s except for a mild elevation of the FR after 270s (p<0.02).</AbstractText>Fractal based measures indicate an increase in the fractal dimension of ischemia induced VF for the first 180s when compared to electrically induced VF. Frequency-based measures uniformly demonstrate a pattern of higher frequencies for electrically induced VF for the first 90s. The increased fractal dimension and decreased frequencies associated with ischemia induced VF may reflect changes in the underlying myocardial physiology that can be used to guide therapies.</AbstractText> |
8,517 | Cardiac troponin I after external electrical cardioversion for atrial fibrillation as a marker of myocardial injury--a preliminary report. | It is uncertain whether external electrical cardioversion (CV) of atrial fibrillation (AF) can cause myocardial injury identifiable by troponin I (cTnI).</AbstractText>To examine whether external CV of AF can cause cTnI rise as measured with high-sensitivity assay, and to identify factors determining this elevation.</AbstractText>Patients with non-valvular AF selected for CV were included. Exclusion criteria were myocardial ischaemia, elevated D-dimer, heart and renal failure. Patients underwent monophasic or biphasic CV. Troponin I was measured before, and 6 and 12 hours after the procedure with TNI-ADV assay; NT-proBNP was measured before CV. Echocardiography was performed in all patients.</AbstractText>Twenty-two patients were examined. Troponin I 6 and 12 hours after CV [0.04 ng/ml (0.00-0.30), 0.04 ng/ml (0.00-0.13)] was significantly higher than before [0.017 pg/ml (0.00-0.08)] (p=0.01, p=0.02). Only in one patient did cTnI exceed the cut-off for myocardial infarction after 6 hours (>0.16 ng/ml) with subsequent normalisation after 12 hours. Left ventricular end-diastolic dimension (LVEDD) was significantly higher and ejection fraction lower in the group with cTnI rise in comparison with the group with no cTnI elevation (54,2+/-6,3 vs. 47,6+/-5,7 mm, p=0,02; 56,2+/-8,9 vs. 63,2+/-7,1%, p=0,05). LVEDD=53 mm had 75% sensitivity and 72% specificity for predicting cTnI elevation after CV. Age, gender, AF duration, type of CV, energy, left atrial dimension, baseline cTnI and NT-proBNP were not predictive of cTnI increase.</AbstractText>Cardioversion can lead to mild but significant cTnI rise as measured with a high-sensitivity assay. The influence of CV on cTnI elevation appears to be more pronounced in patients with relatively large LVEDD.</AbstractText> |
8,518 | Spontaneous defibrillation after cessation of resuscitation in out-of-hospital cardiac arrest: a case of Lazarus phenomenon. | This report describes a case of out-of-hospital cardiac arrest with spontaneous defibrillation and subsequent return of circulation after cessation of resuscitative efforts. A 47-year-old man was found in cardiac arrest and resuscitation was initiated. As no response was achieved, the efforts were withdrawn and final registered cardiac rhythm was ventricular fibrillation. Fifteen minutes later the patient was found to be normotensive and breathing spontaneously. The patient made a poor neurological recovery and died 3 months after the arrest. The authors are unable to give an explanation to the event, but suspect the effect of adrenaline combined with mild hypothermia to have contributed to the self-defibrillation of the myocardium. |
8,519 | Return of spontaneous circulation and survival at hospital discharge in patients with out-of-hospital and emergency department cardiac arrests in a tertiary care centre. | To examine clinical variables and outcomes in patients with out-of-hospital (unwitnessed) and emergency department (ED; witnessed) cardiac arrests at a tertiary care hospital in Karachi.</AbstractText>A prospective observational study was conducted to note that outcomes in patients with first attempted cardiopulmonary resuscitation in the Emergency Department of the Aga Khan University Hospital, Karachi, between Jan. 2000 and Dec. 2000. Cardiac arrest was defined as absence of a palpable central pulse and apnoea. Return of spontaneous circulation (ROSC) and survival at hospital discharge were primary outcomes. Logistic regression was applied to determine predictors for ROSC.</AbstractText>Of 106 patients with cardiac arrest, 59% (n = 62/106) patients had ROSC [52% (n = 29/56) of unwitnessed group; 64% (n = 32/50) of witnessed group]. Mean age was 48 years (range: 27-86); 68% (n = 72/106) were males; and 41% (n = 43/106) had ventricular fibrillation (VF) as initial rhythm. Male gender (OR 0.381; CI 0.156-0.928), PEA (OR 0.175; CI 0.063-0.489, reference VF) and asystole (OR 0.328; CI 0.114-0.944, reference VF) were negatively associated with ROSC. Less than ten minutes duration of CPR (OR 63.628; CI 8.221-429.457) and one co-morbidity status (OR 3.607; CI: 1.26-10.327, reference two or more co-morbidities) were positively associated with ROSC. Overall, 22% (n = 23/106) of enrolled patients left the hospital alive: 34% (n = 17/50) of the witnessed group and 12% (n = 6/56) of the unwitnessed group.</AbstractText>Out of hospital arrest was associated with dismal survival at hospital discharge, emphasizing the need for development of pre-hospital care services for our country.</AbstractText> |
8,520 | ANP and BNP in atrial fibrillation before and after cardioversion--and their relationship to cardiac volume and function. | The role of atrial (ANP) and B-type (BNP) natriuretic peptide in atrial fibrillation (AF) is not clear. Our aim was to describe ANP and BNP in AF, and their changes following cardioversion in persistent AF. Furthermore, we wanted to assess the association between ANP and BNP and cardiac volume and function evaluated by magnetic resonance imaging. ANP and BNP decreased significantly following cardioversion. After 180 days of sinus rhythm, ANP and BNP were still significantly elevated. Same results were seen in patients with lone AF. Left and right atrial volumes correlated positively with ANP and BNP. Changes in left atrial volume were predictive of changes in ANP and BNP following cardioversion. AF may cause enduringly elevated ANP and BNP and atrial volume seems to be an important determinant of ANP and BNP in AF. |
8,521 | Safety and predictors of complications with a new accelerated dobutamine stress echocardiography protocol. | This study sought to document the safety of a new accelerated dobutamine-atropine stress echocardiography protocol and to analyze its complications.</AbstractText>Dobutamine-atropine stress echocardiography studies were performed using an incremental dobutamine infusion protocol from 20 to 40 microg/kg/min in 3-minute stages and followed by atropine.</AbstractText>A total of 962 patients were included. Mean age was 64 +/- 11 years and 584 were male (61%). Mean ejection fraction was 62 +/- 10%. Complications included hypertensive responses in 66 patients (7%), arrhythmias in 26 (2.7%), and symptomatic hypotension in 16 (1.7%). No patient developed heart failure, acute myocardial infarction, ventricular fibrillation, or died. The independent predictors of hypertensive responses were age, baseline systolic blood pressure, and treatment with nitrates. The independent predictors of arrhythmias were history of hypertension, previous coronary artery disease, and baseline heart rate.</AbstractText>This accelerated dobutamine-atropine stress echocardiography protocol is safe in a low-risk population and has a rate of complications similar to that reported for the standard protocol.</AbstractText> |
8,522 | Assessment of intraventricular systolic asynchrony in patients with atrial fibrillation using triplane tissue Doppler imaging. | Triplane tissue Doppler imaging (TDI) makes it possible to simultaneously obtain three apical view images and to measure the dyssynchrony index (DS) for 12 segments in patients with atrial fibrillation (AF). We evaluated the feasibility of using triplane TDI to assess intraventricular asynchrony in AF.</AbstractText>In 50 patients with AF, triplane TDI was used for the analysis of myocardial velocity curves of 12 (six basal and six mid) left ventricular (LV) segments by apical two-, three-, and four-chamber views. Time to peak systolic velocity (Ts) was measured, and DS was calculated as the standard deviation (SD) of Ts over 12 segments. The DS(avg) was defined as the average of DS of eight consecutive cycles. To assess the cyclic variability of DS, the coefficient of variation of DS (CoV(DS)) was calculated as the SD of DS for eight cycles divided by DS(avg) [SD(DS)/DS(avg)]. CoV(RR), representing the variability of RR intervals, was defined as [SD(RR)/RR(avg)]. Patients with a left ventricular ejection fraction (LVEF) of 45% or more were classified as group A, and patients with an LVEF less than 45% as were classified as group B.</AbstractText>The mean LVEF was 47% +/- 12%. Group B showed larger LV volume and lower sphericity index compared with group A. Intraobserver and interobserver variability of DS(avg) were 6% and 9%, respectively. More severe dyssynchrony was observed in group B (DS(avg); 23.5 +/- 8.5 ms in group B vs. 17.7 +/- 6.1 ms in group A, P = .008). DS(avg) was not related to RR(avg) or CoV(RR). DS(avg) negatively correlated with ejection fraction (r = -0.404, P = .004) and sphericity index (r = -0.317, P = .025) and showed positive correlation with LV volume.</AbstractText>Analysis of asynchrony by triplane TDI was feasible in patients with AF. DS(avg) correlated with echocardiographic parameters of systolic function.</AbstractText> |
8,523 | The effects of changes to the ERC resuscitation guidelines on no flow time and cardiopulmonary resuscitation quality: a randomised controlled study on manikins. | The European Resuscitation Council (ERC) guidelines changed in 2005. We investigated the impact of these changes on no flow time and on the quality of cardiopulmonary resuscitation (CPR).</AbstractText>Simulated cardiac arrest (CA) scenarios were managed randomly in manikins using ERC 2000 or 2005 guidelines. Pairs of paramedics/paramedic students treated 34 scenarios with 10min of continuous ventricular fibrillation. The rhythm was analysed and defibrillation shocks were delivered with a semi-automatic defibrillator, and breathing was assisted with a bag-valve-mask; no intravenous medication was given. Time factors related to human intervention and time factors related to device, rhythm analysis, charging and defibrillation were analysed for their contribution to no flow time (time without chest compression). Chest compression quality was also analysed.</AbstractText>No flow time (mean+/-S.D.) was 66+/-3% of CA time with ERC 2000 and 32+/-4% with ERC 2005 guidelines (P<0.001). Human factor interventions occupied 114+/-4s (ERC 2000) versus 107+/-4s (ERC 2005) during 600-s scenarios (P=0.237). Device factor interventions took longer using ERC 2000 guidelines: 290+/-19s versus 92+/-15s (P<0.001). The total number of chest compressions was higher with ERC 2005 guidelines (808+/-92s versus 458+/-90s, P<0.001), but the quality of CPR did not differ between the groups.</AbstractText>The use of a single shock sequence with guidelines 2005 has decreased the no flow time during CPR when compared with guidelines 2000 with multiple shocks.</AbstractText> |
8,524 | Nitric oxide mediates the vagal protective effect on ventricular fibrillation via effects on action potential duration restitution in the rabbit heart. | We have previously shown that direct vagus nerve stimulation (VNS) reduces the slope of action potential duration (APD) restitution while simultaneously protecting the heart against induction of ventricular fibrillation (VF) in the absence of any sympathetic activity or tone. In the current study we have examined the role of nitric oxide (NO) in the effect of VNS. Monophasic action potentials were recorded from a left ventricular epicardial site on innervated, isolated rabbit hearts (n = 7). Standard restitution, effective refractory period (ERP) and VF threshold (VFT) were measured at baseline and during VNS in the presence of the NO synthase inhibitor N(G)-nitro-L-arginine (L-NA, 200 microm) and during reversing NO blockade with L-arginine (L-Arg, 1 mm). Data represent the mean +/- S.E.M. The restitution curve was shifted upwards and became less steep with VNS when compared to baseline. L-NA blocked the effect of VNS whereas L-Arg restored the effect of VNS. The maximum slope of restitution was reduced from 1.17 +/- 0.14 to 0.60 +/- 0.09 (50 +/- 5%, P < 0.0001) during control, from 0.98 +/- 0.14 to 0.93 +/- 0.12 (2 +/- 10%, P = NS) in the presence of L-NA and from 1.16 +/- 0.17 to 0.50 +/- 0.10 (41 +/- 9%, P = 0.003) with L-Arg plus L-NA. ERP was increased by VNS in control from 119 +/- 6 ms to 130 +/- 6 ms (10 +/- 5%, P = 0.045) and this increase was not affected by L-NA (120 +/- 4 to 133 +/- 4 ms, 11 +/- 3%, P = 0.0019) or L-Arg with L-NA (114 +/- 4 to 123 +/- 4 ms, 8 +/- 2%, P = 0.006). VFT was increased from 3.0 +/- 0.3 to 5.8 +/- 0.5 mA (98 +/- 12%, P = 0.0017) in control, 3.4 +/- 0.4 to 3.8 +/- 0.5 mA (13 +/- 12%, P = 0.6) during perfusion with L-NA and 2.5 +/- 0.4 to 6.0 +/- 0.7 mA (175 +/- 50%, P = 0.0017) during perfusion with L-Arg plus L-NA. Direct VNS increased VFT and flattened the slope of APD restitution curve in this isolated rabbit heart preparation with intact autonomic nerves. These effects were blocked using L-NA and reversed by replenishing the substrate for NO production with L-Arg. This is the first study to demonstrate that NO plays an important role in the anti-fibrillatory effect of VNS on the rabbit ventricle, possibly via effects on APD restitution. |
8,525 | Novel anti-arrhythmic drugs for atrial fibrillation management. | Atrial fibrillation (AF) is a highly prevalent arrhythmia and responsible for significant morbidity, mortality and health care cost. Considerable work has been performed to improve medical options but treatment success still remains suboptimal. The use of conventional anti-arrhythmic agents has been limited by potentially fatal ventricular proarrhythmia. Thus, novel drug targets have been characterised and are currently being tested in experimental and clinical studies. The atrially (but not ventricularly) expressed ion channel subunit Kv1.5 (conducting the ultra-rapid delayed rectifier, I(Kur)) is a prominent candidate. A variety of drugs that inhibit this current is being evaluated. Human experience with these agents is limited. Atrial expression of connexin 40 and downregulation of this protein in AF turn its modulation into a potential therapeutic approach. The acetylcholine-activated current (I(KACh)) is another novel candidate target for drug therapy. The constitutively active form of this current is increased in human AF and pharmacological inhibition might be of therapeutic value. Certain drugs have I(KACh) blocking properties, but as for I(Kur)-blockers none to date has shown pure selectivity for this current. This article summarizes relevant aspects of the cellular electrophysiology of AF and reviews the actions of pharmacological agents presently available or in development as novel anti-arrhythmic therapy. |
8,526 | Predictors of atrial fibrillation after coronary artery bypass surgery. | Atrial fibrillation is one of the most common arrhythmias associated with not only increased morbidity after coronary artery bypass grafting but also increased healthcare costs. Many factors are associated with atrial fibrillation onset after coronary artery bypass grafting. We prospectively examined which factors could predict atrial fibrillation after coronary artery bypass grafting.</AbstractText>Fifty-seven consecutive patients (37 men, mean age=60.2+/-12 years) with sinus rhythm before coronary artery bypass grafting are included the study. Clinical, demographic, laboratory and echocardiographic characteristics are all evaluated prospectively. The maximum and minimum P-wave duration (P(max) and P(min)) were measured from the 12-lead surface electrocardiogram. The difference between the P(max) and the P(min) was calculated and defined as P-wave dispersion. Preoperative venous blood samples were taken for N-terminal proBrain natriuretic peptide level analysis.</AbstractText>Ten (17%) patients had postoperative atrial fibrillation. Patients with postoperative atrial fibrillation were older (69.4+/-6 versus 58.2+/-12 years, P=0.01), had lower ejection fraction (44.1+/-8.9% versus 54.3+/-9; P=0.002), higher proBrain natriuretic peptide levels (538+/-136 pg/ml versus 293+/-359 pg/ml; P=0.03), longer P(max) (142.2+/-13.7 ms versus 120.8+/-21.2 ms; P=0.006) and longer P-wave dispersion (55.0+/-8.2 ms versus 41.3+/-14.3 ms; P=0.008) compared with the patients without atrial fibrillation. Univariate analysis showed that increased age (P=0.01), lower ejection fraction (P=0.02), enlargement of left atrium (P=0.02), increased P(max) (P=0.006) and increased P-wave dispersion (P=0.008) and increased level of preoperative proBrain natriuretic peptide (P=0.03) were associated with postoperative atrial fibrillation. Positive correlation was seen between the age and level of proBrain natriuretic peptide (r=0.322 and P=0.015). In multivariate analysis, age (P=0.05), lower ejection fraction (P=0.03), left atrial enlargement (P=0.05), longer P(max) (P=0.01) and P-wave dispersion (P=0.01) were found to be independent predictors of postoperative atrial fibrillation.</AbstractText>Age, poor left ventricular functions, P(max) and P-wave dispersion are found to be independent predictors of atrial fibrillation after coronary artery bypass grafting.</AbstractText> |
8,527 | Strain rate imaging for noninvasive functional quantification of the left atrium in hypertensive patients with paroxysmal atrial fibrillation. | Strain rate (SR) imaging has been applied to the detection of regional left ventricular (LV) dysfunction but not as much to the assessment of left atrial (LA) function. We aimed to assess atrial myocardial properties during atrial fibrillation (AF) by myocardial velocity, SR and strain, focusing on the effects of hypertension and atrial arrhythmias, especially paroxysmal AF.</AbstractText>We compared 3 groups of a total of 110 consecutive patients with hypertension presenting to our institution: 20 with brief atrial tachycardia, 20 with paroxysmal AF and 70 with hypertension alone. These patients and 32 controls underwent transthoracic echocardiography, tissue velocity imaging (TVI), strain examination and SR imaging. Atrial tissue velocity, strain and SR values of hypertensive patients were compared with those of age-matched controls.</AbstractText>Compared with controls, hypertensive patients with paroxysmal AF showed significantly increased atrial myocardial features as assessed by TVI (p < 0.05-0.001). Time to peak late diastolic SR corrected for heart rate (TASRc) and the difference of early diastolic SR (deltaESR) were significantly increased (both p < 0.05), whereas the difference of late diastolic SR (deltaASR) (p < 0.05) and the difference of TASRc (deltaTASRc) (p < 0.001) were significantly decreased; moreover, systolic SR (SSR), deltaASR and deltaTASRc were significantly decreased (p < 0.05, p < 0.01 and p < 0.001, respectively), whereas deltaESR was significantly increased (p < 0.01), as compared with hypertensive patients without arrhythmia. No other parameters differed among the 4 groups.</AbstractText>SR imaging combined with TVI enables noninvasive quantification of LA dysfunction due to hypertension and paroxysmal AF. In hypertensive patients, paroxysmal AF decreases the efficiency, not the ability, of LA myocardia to reserve potential energy, which suggests that LA myocardial reservoir function decreases. The impaired conductivity of the left atrium leads to decreased total active atrial contraction and prolonged interatrial conduction. Thus, the temporal asynchrony of the atria is enhanced, but contraction asynchrony is reduced.</AbstractText>(c) 2007 S. Karger AG, Basel</CopyrightInformation> |
8,528 | Characterization of the acute cardiac electrophysiologic effects of ethanol in dogs. | Alcohol has been related to atrial fibrillation (holiday heart syndrome), but its electrophysiologic actions remain unclear.</AbstractText>We evaluated the effects of alcohol in 23 anesthetized dogs at baseline and after 2 cumulative intravenous doses of ethanol: first dose 1.5 ml/kg (plasma level 200 mg/dl); second dose 1.0 ml/kg (279 mg/dl). In 13 closed-chest dogs (5 with intact autonomic nervous system, 5 under combined autonomic blockade and 3 sham controls), electrophysiologic evaluation and monophasic action potential (MAP) recordings were undertaken in the right atrium and ventricle. In 5 additional dogs, open-chest biatrial epicardial mapping with 8 bipoles on Bachmann's bundle was undertaken. In the remaining 5 dogs, 2D echocardiograms and ultrastructural analysis were performed.</AbstractText>In closed-chest dogs with intact autonomic nervous system, ethanol had no effects on surface electrocardiogram and intracardiac variables. At a cycle length of 300 milliseconds, no effects were noted on atrial and ventricular refractoriness and on the right atrial MAP. These results were not altered by autonomic blockade. No changes occurred in sham controls. In open-chest dogs, ethanol did not affect inter-atrial conduction time, conduction velocity, and wavelength. Atrial arrhythmias were not induced in any dog, either at baseline or after ethanol. Histological and ultrastructural findings were normal but left ventricular (LV) ejection fraction decreased in treated dogs (77 vs. 73 vs. 66%; p = 0.04).</AbstractText>Ethanol at medium and high doses depresses LV systolic function but has no effects on atrial electrophysiological parameters. These findings suggest that acute alcoholic intoxication does not directly promote atrial arrhythmias.</AbstractText> |
8,529 | Arginine vasopressin during sinus rhythm: effects on haemodynamic variables, left anterior descending coronary artery cross sectional area and cardiac index, before and after inhibition of NO-synthase, in pigs. | We have shown previously that arginine vasopressin (AVP) given during sinus rhythm increases mean arterial blood pressure (MAP) and left anterior descending (LAD) coronary artery cross sectional area. AVP was assumed to result in vasodilatation via activation of the endothelial nitric oxide system. The purpose of the present study was to assess the effects of AVP before and after NO-inhibition. Nine domestic pigs were instrumented for measurement of haemodynamic variables using micromanometer-tipped catheters, and measurement of LAD coronary artery cross sectional area employing intravascular ultrasound (IVUS). Haemodynamic variables, LAD coronary artery cross sectional area and cardiac output were measured at baseline, 90 s and 5, 15, and 30 min after AVP (0.4 U kg (-1) IV) before and after blockade of nitric oxide synthase with N(G)-nitro L-arginine methyl ester (L-NAME). Compared with baseline, AVP significantly increased MAP after 90 s (89+/-4 versus 160+/-5 mm Hg), increased LAD coronary artery cross sectional area (11.3+/-1 versus 11.8+/-1 mm(2)) and decreased cardiac index (138+/-6 versus 53+/-6 mL/min kg(-1)). After blockade of nitric oxide synthase, AVP significantly increased MAP after 90 s (135+/-4 versus 151+/-3 mm Hg), increased LAD coronary artery cross sectional area (8.7+/-1 versus 8.9+/-1 mm(2)), and significantly decreased cardiac index (95+/-6 versus 29+/-4 mL/min kg (-1)).</AbstractText>During sinus rhythm, AVP increased MAP and LAD coronary artery cross sectional area, but decreased cardiac index.</AbstractText> |
8,530 | PCI of the right coronary artery via or under struts of stents protruding into the aorta. | Reported are two cases in which stent protrusion from the right coronary ostium into the aorta caused considerable difficulty in interventions. Two different methods were applied to overcome this problem. In the first (elective) case a new orifice was created at the side of the protruding stent. In the second case (acute inferoposterior and right myocardial infarction associated with complete heart block, recurrent ventricular fibrillation and shock), a new track was created underneath the underexpanded protruding stent, and the protruding stent was crushed under a new stent. Stents protruding from the right coronary artery into the aorta may present a considerable challenge during interventions, which can be managed by certain technical modifications. |
8,531 | Catheter ablation techniques in managing arrhythmias. | Pharmacological management of arrhythmias is not curative, is sometimes difficult, and may be associated with significant morbidity.</AbstractText>This article discusses the place of catheter ablation in the treatment of arrhythmias.</AbstractText>Supraventricular and typical atrial flutter can be cured with catheter ablation in approximately 95% of cases with very low complication rates. Catheter ablation can successfully restore and maintain sinus rhythm in patients with atrial fibrillation (AF) and should be considered in symptomatic patients not controlled on medical therapy before the initiation of amiodarone. Results for AF ablation are best in paroxysmal patients without structural heart disease. Ventricular tachycardia in patients without structural heart disease is readily treated with catheter ablation. Catheter ablation is an effective adjunct to an implantable cardioverter defibrillator in patients with ventricular tachycardia postmyocardial infarction.</AbstractText> |
8,532 | Pharmacologic management of tachycardia. | Cardiac arrhythmias may present with palpitations, chest pain, shortness of breath, dizziness and syncope. Diagnosis may be complicated by an inability to document the arrhythmia particularly when symptoms are infrequent and short lived.</AbstractText>This article aims to provide an overview of the pharmacological management of supraventricular tachycardia including atrial flutter and haemodynamically stable ventricular tachycardia. Management of atrial fibrillation is discussed in a companion article in this issue.</AbstractText>Antiarrhythmic medications are effective in reducing symptoms, however, side effects are frequent. Fortunately nonpharmacological strategies such as catheter ablation have evolved which offer long term cure in the majority of patients. However, despite technological advances, pharmacotherapy retains an important place in the therapeutic approach to cardiac arrhythmias in many patients. It is important to remember that pharmacological management should also address any underlying cardiac disease process.</AbstractText> |
8,533 | Emergency management of acute cardiac arrhythmias. | Anything other than normal sinus rhythm can be classified as an arrhythmia. However not all arrhythmias need acute intervention.</AbstractText>This article reviews which arrhythmias need intervention in an acute setting, and the various options available for intervention.</AbstractText>The impact of an arrhythmia upon perfusion determines what intervention should be considered. Conscious level, cardiac ischaemia secondary to poor perfusion of the coronary arteries and blood pressure need to be assessed. Patients with bradycardias with adequate perfusion are treated initially with oxygen and observation. Sinus bradycardia not responding to increased oxygenation is treated with atropine. For other bradycardias the two alternatives are to drive the inherent rate with a sympathomimetic drug or to pace the patient with an external or internal pacer. Usually supraventricular tachycardias are not life threatening. Unconscious patients with wide complex tachycardia should be treated in a standard cardiac arrest approach. Conscious patients in ventricular fibrillation however, can be treated either chemically or with synchronised cardioversion. If a patient is in cardiac arrest the approach is to establish effective resuscitation and early defibrillation as per Australian Resuscitation Council guidelines.</AbstractText> |
8,534 | The combination of B-type natriuretic peptide and C-reactive protein provides incremental prognostic value among older patients referred for cardiac catheterization. | Recent clinical studies have demonstrated the utility of B-type natriuretic peptide (BNP) and C-reactive protein (CRP) for predicting cardiovascular outcomes. The authors hypothesized that a combined biomarker score would provide incremental prognostic value among older individuals. Clinical data, biomarkers, and echocardiograms were obtained in 200 geriatric patients referred for cardiac catheterization. Tertile score was defined as the sum of an individual's BNP tertile plus CRP tertile within the study population, for a total score from 2 to 6. The primary end point was cardiovascular hospitalization or death at 6 months. Univariate predictors of events included prior heart failure, atrial fibrillation, left ventricular systolic dysfunction, functional class, significant mitral regurgitation, BNP, CRP, and the tertile score. In contrast to BNP or CRP alone, the tertile score consistently provided incremental value when added to clinical predictors in multivariate models. A simple summation score may help clinicians predict outcomes in symptomatic geriatric patients beyond standard clinical variables. |
8,535 | Antiarrhythmic induced electrical storm in Brugada syndrome: a case report. | Brugada syndrome (BS) may be "unmasked" by several pharmacological and/or physiological agents in an otherwise normal electrocardiogram. Once diagnosed the possibility of persistent ventricular tachycardia/fibrillation exists. Although this is treated with various antiarrhythmic agents, there remains a cohort of patients who fail to respond to conventional antiarrhythmic therapy therefore, amplifying the electrical storm. We report a case of a BS diagnosed via procainamide challenge, the resultant near fatal electrical storm aggravated by amiodarone and the eventual resolution with isoproterenol. |
8,536 | Vulnerability to reentry in a regionally ischemic tissue: a simulation study. | Sudden cardiac death is mainly provoked by arrhythmogenic processes. During myocardial ischemia many malignant arrhythmias, such as reentry, take place and can degenerate into ventricular fibrillation. It is thus of great interest to unravel the intricate mechanisms underlying the initiation and maintenance of a reentry. In this computational study, we analyze the probability of reentry during different stages of the acute phase of ischemia. We also aimed at the understanding of the role of its main components: hypoxia, hyperkalemia, and acidosis analyzing the intricate ionic mechanisms responsible for reentry generation. We simulated the electrical activity of a ventricular tissue affected by regional ischemia based on a modified version of the Luo-Rudy model (LRd00). The ischemic conditions were varied to simulate different stages of this pathology. After premature stimulation, we evaluated the vulnerability to reentry. We obtained an unimodal behavior for the vulnerable window as ischemia progressed, peaking at the eighth minute after the onset of ischemia where the vulnerable window yielded 58 ms. Under more severe conditions the vulnerable window decreased and became zero for minute 8.75. The present work provides insight into the mechanisms of reentry generation during ischemia, highlighting the role of acidosis and hypoxia when hyperkalemia is present. |
8,537 | Isolated left ventricular noncompaction in a patient presenting with a subacute myocardial infarction. | Isolated left ventricular noncompaction is a rare cardiomyopathy that is often not recognised. So far, it is not well established how best to manage this abnormality. We describe a patient in whom the diagnosis of isolated left ventricular noncompaction was made after presentation with a subacute myocardial infarction. Because of nonsustained ventricular tachycardias during hospitalisation, which were inducible and deteriorated into ventricular fibrillation on electrophysiological examination after coronary artery bypass grafting, he received an implantable defibrillator. Whether the ventricular tachycardias were due to the myocardial infarction or to the noncompacted myocardium remains uncertain. (Neth Heart J 2007;15:109-11.). |
8,538 | [Emergency therapy for acute heart failure]. | Acute heart failure (AHF) is defined as the rapid onset of symptoms and signs secondary to abnormal heart function which may occur with or without previous cardiac disease. Diagnosis and classification of severity are primarily based on clinical findings. The conditions leading to and reasons for acute heart failure which require specific therapeutic interventions should always be taken into consideration. Immediate goals in the guideline-oriented treatment of AHF are to improve the patient's symptoms and stabilize the hemodynamic condition. Medical therapy - besides oxygen supply - consists of the application of vasodilators, diuretics, and inotropes (especially dobutamine) depending both on the patient's clinical state and hemodynamic parameters. In the presence of ongoing signs of hypoxia, non-invasive ventilation has to be considered early. Bradycardia in AHF patients should initially be treated with atropine; a temporal pacemaker has to be inserted if no response is achieved by medical therapy. Ventricular fibrillation and tachycardia require immediate cardioversion. |
8,539 | Fatal cardiac tamponade as a result of a peripherally inserted central venous catheter: a case report and review of the literature. | We present a case of fatal cardiac tamponade that occurred in association with a peripherally inserted central catheter (PICC) inserted from the right antecubital fossa. Migration of the catheter from the right atrium within 24 h of insertion lead to the administration of a potassium-enriched sodium chloride solution into the pericardial space with the development of ST-segment elevation and progression to pulseless electrical activity and, subsequently, ventricular fibrillation. Although signs of tamponade were seen on echocardiography, we propose that myocardial hyperkalaemia from the diffusion of potassium through the epicardium accounted for some of the clinical picture. PICC lines carry a greater risk of migration because of the tip movement associated with arm abduction and, therefore, care must be taken to ensure that the catheter tip is correctly positioned to reduce this risk. When such catheters are used for intra-operative central venous access, we believe chest radiography is mandatory before fluid administration through the catheter, but that this is unnecessary when the catheter is being used solely for central venous pressure monitoring. The use of softer catheters may reduce the risk of vessel perforation. Once tamponade is suspected, all drugs and infusions administered via the catheter should be reviewed, the catheter aspirated and echocardiography performed urgently. This may be facilitated by the greater availability of limited bedside echocardiography within critical care units and theatre complexes. |
8,540 | Use of implantable cardioverter defibrillators in Canadian and US survivors of out-of-hospital cardiac arrest. | Cardiac arrest due to ventricular arrhythmia in the absence of a reversible cause or contraindication has been a class I indication for insertion of an implantable cardioverter defibrillator since 1998. We compared and contrasted the use of implantable cardioverter defibrillator therapy in Canada and the United States among adults who survived a cardiac arrest.</AbstractText>Data on hospital separations from April 1, 1994 through March 31, 2003 were obtained from the Health Person-Oriented Information Database maintained by Statistics Canada and from the US National Hospital Discharge Survey on all patients with a primary diagnosis of cardiac arrest, ventricular fibrillation or ventricular flutter for the same 9-year period. We excluded all records of patients with a secondary diagnosis of acute myocardial infarction.</AbstractText>In Canada, 3793 patients survived to discharge after a cardiac arrest; 628 (16.6%) of these were implanted with a cardioverter defibrillator before discharge. The implant rate rose steadily from 5.4% in 1994/95 to 26.7% in 2002/03. In the United States, 23 688 (30.2%) of 78 538 such survivors received an implantable cardioverter defibrillator before discharge. Logistic regression analysis indicated that sex, age, fiscal year, the hospital's teaching status, hospital size and patient history of heart failure were positive predictors of implantable cardioverter defibrillator implantation. Age, renal failure, liver failure and cancer were negative predictors of receiving an implantable cardioverter defibrillator.</AbstractText>The rate of use of implantable cardioverter defibrillator therapy for cardiac arrest survivors in Canada is increasing, but still is lower than the rate in the United States.</AbstractText> |
8,541 | Cardiac beat-to-beat alternations driven by unusual spiral waves. | Alternans, a beat-to-beat temporal alternation in the sequence of heartbeats, is a known precursor of the development of cardiac fibrillation, leading to sudden cardiac death. The equally important precursor of cardiac arrhythmias is the rotating spiral wave of electro-mechanical activity, or reentry, on the heart tissue. Here, we show that these two seemingly different phenomena can have a remarkable relationship. In well controlled in vitro tissue cultures, isotropic populations of rat ventricular myocytes sustaining a temporal rhythm of alternans can support period-2 oscillatory reentries and vice versa. These reentries bear "line defects" across which the phase of local excitation slips rather abruptly by 2pi, when a full period-2 cycle of alternans completes in 4pi. In other words, the cells belonging to the line defects are period-1 oscillatory, whereas all of the others in the bulk medium are period-2 oscillatory. We also find that a slowly rotating line defect results in a quasi-periodic like oscillation in the bulk medium. Some key features of these phenomena can be well reproduced in computer simulations of a nonlinear reaction-diffusion model. |
8,542 | A simpler cardiac arrest model in rats. | Two disadvantages of electrical induction of cardiac arrest used currently are that it is a technically complicated procedure and the consequent thermal injury, which prompts us to search for a simpler method with less adverse effect to induce ventricular fibrillation (VF) in rats. Different potential (18, 24, 30, and 36 V) of alternating current (AC) were administered to elicit VF in 15 rats via pacing electrode placed in esophagus. Four minutes after onset of VF, conventional cardiopulmonary resuscitation (CPR) was initiated. Restoration of spontaneous circulation was defined as the return of supraventricular rhythm with a mean aortic pressure of 20 mm Hg or greater for a minimum of 5 minute. Ventricular fibrillation was achieved by short interval of AC stimulation in all of the rats. After the termination of prolonged AC stimulation, electrocardiogram indicated VF occurred in 6 of 15 rats, asystole in 3 of 15 rats and pulseless electrical activity in 6 of 15 rats. Before CPR, however, electrocardiogram indicated that only 2 of 15 and 4 of 15 animals remained in VF and pulseless electrical activity, respectively, whereas 9 of 15 animals presented as asystole. After CPR, 11 of 15 animals were resuscitated. Necropsy showed that there was no gross evidence of thermal injury on the surface layer of the heart. Therefore, development of a rat cardiac arrest model by transesophageal AC stimulation is simpler and less adverse effect, which may have practical significance for facilitating experimental investigation on cardiac arrest and CPR. |
8,543 | New antiarrhythmic treatment of atrial fibrillation. | Antiarrhythmic pharmaceutical development for the treatment of atrial fibrillation (AF) is moving in several directions. The efficacy of existing drugs, such as carvedilol, for rate control and, possibly, suppression of AF, is more appreciated. Efforts are being made to modify existing agents, such as amiodarone, in an attempt to ameliorate safety and adverse effect concerns. This has resulted in promising data from the deiodinated amiodarone analog, dronedarone, and further work with celivarone and ATI-2042. In an attempt to minimize ventricular proarrhythmia, atrial selective drugs, such as intravenous vernakalant, have demonstrated efficacy in terminating AF in addition to promising data in suppression recurrences when used orally. Several other atrial selective drugs are being developed by multiple manufacturers. Other novel therapeutic mechanisms, such as drugs that enhance GAP junction conduction, are being developed to achieve more effective drug therapy than is offered by existing compounds. Finally, nonantiarrhythmic drugs, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, high-mobility group coenzyme A enzyme inhibitors and omega-3 fatty acids/fish oil, appear to have a role in suppressing AF in certain patient subtypes. Future studies will clarify the role of these drugs in treating AF. |
8,544 | Atrial overdrive pacing and incidence of heart failure-related adverse events in permanently paced patients. | Atrial overdrive pacing algorithms may be effective in preventing or suppressing atrial fibrillation (AF). However, the maintenance of a heart rate incessantly faster than spontaneous could induce left ventricular (LV) dysfunction and promote heart failure (HF) on the long term.</AbstractText>This post hoc analysis examined the effects of a new overdrive algorithm on the incidence of HF-related adverse events in 411 patients enrolled in the ADOPT-A trial.</AbstractText>The AF Suppression algorithm was randomly programmed ON in 209 patients (treatment group) versus OFF in 202 patients (control group). The incidence of HF-related adverse events and HF-related deaths over a 6-month follow-up was compared between the two groups. Patients with versus without HF-related clinical events were also compared to each other within each group.</AbstractText>There were eight HF-related adverse clinical events (3.8%) in the treatment group and 11 (5.4%) in the control group, including four HF-related deaths (1.9 vs. 2.0%) in each group during follow-up. Baseline NYHA functional class in patients with versus without HF-related adverse events was 1.4 +/- 0.5 versus 1.5 +/- 0.7 in the control, and 1.5 +/- 0.8 versus 1.5 +/- 0.6 in the treatment group. LV ejection fraction (EF) was 49 +/- 7% in patients with, versus 57 +/- 12% in patients without HF-related adverse events, in the control group, and 43 +/- 14% in patients with, versus 56 +/- 13% in patients without HF-related adverse events, in the treatment group. LVEF was lowest and similar in both groups among patients who died from HF (35 +/- 10% in the control and 38 +/- 27% in the treatment group).</AbstractText>In ADOPT-A, HF-related clinical events and deaths were related to LV dysfunction and not to atrial pacing overdriven by the AF suppression algorithm.</AbstractText> |
8,545 | Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation. | In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus formation in patients with AF is unknown and was consequently evaluated in this study.</AbstractText>One-hundred and twenty-five patients (mean age 64 +/- 12 years, 72% male) with persistent non-valvular AF (mean duration 28 +/- 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time-frequency analysis of lead V1. Atrial fibrillatory rate measured 401 +/- 63 fibrillations per minute (fpm, range 235-566 fpm) and was related with age (R = -0.326, P < 0.001), ventricular rate (R = -0.202, P = 0.024), gender (407 +/- 62 in males vs. 387 +/- 64 fpm in females, P = 0.038) but not AF duration (R = 0.088, P = 0.374), presence of lone AF (408 +/- 66 vs. 394 +/- 58 fpm, P = 0.228), or beta-blocker or calcium channel blocker treatment (398 +/- 63 vs. 405 +/- 62 fpm, P = 0.556). Age was the only independent predictor of fibrillatory rate (B = -1.714, P < 0.001). In patients with left atrial thrombus (n = 10), spontaneous echo contrast (SEC) was more frequently present (70 vs. 29 %, p = 0.007) and left atrial appendage (LAA) outflow velocity was lower (26 +/- 20 vs. 37 +/- 15 cm/s, P = 0.012) than in patients without thrombus (n = 115). In contrast, mean fibrillatory rate, which showed a weak inverse correlation with LAA velocity (R = -0.118, P = 0.048) was not different between both groups (380 +/- 56 vs. 403 +/- 63 fpm, P = 0.226). Similarly, presence of thrombus and SEC combined was not related with fibrillatory rate.</AbstractText>Atrial fibrillatory rate obtained from surface ECG lead V1 is not a risk marker for left atrial thrombus formation in AF.</AbstractText> |
8,546 | Brief review: anesthetic implications of long QT syndrome in pregnancy. | To review the effects of the long QT syndrome (LQTS) in the parturient and the current anesthetic management of patients with LQTS.</AbstractText>Relevant articles were obtained from a MEDLINE search spanning the years 1980-2006 and a PubMed search spanning the years 1949-2006. Bibliographies of retrieved articles were searched for additional articles.</AbstractText>The prevalence of LQTS in the developed world is one per 1,100 to 3,000 of the population. Clinically, LQTS is characterized by syncope, cardiac arrest and occasionally, by a history of seizures. The QT interval can also be prolonged by drugs, electrolyte imbalances, toxins and certain medical conditions. Long QT syndrome patients are at risk of torsades de pointes and ventricular fibrillation. Medical management aims to reduce dysrhythmia frequency. The LQTS is subdivided into different groups (LQT1-6) depending on the cardiac ion channel abnormality. Torsades can be precipitated by adrenergic stimuli such as stress or pain (LQT1 and 2), sudden noises (LQT2) or whilst sleeping (LQT3). Patients with LQTS require careful anesthetic management as they are at high risk of torsades perioperatively despite minimal data on the effects of anesthetic agents on the QT interval. While information on effects of LQTS in pregnancy is limited, the incidence of dysrhythmia increases postpartum. Isolated case reports of patients with LQTS women highlight several peripartum dysrhythmias.</AbstractText>An understanding of LQTS and the associated risk factors contributing to dysrhythmias is important for anesthesthesiologists caring for parturients with LQTS.</AbstractText> |
8,547 | Ganglionated plexi modulate extrinsic cardiac autonomic nerve input: effects on sinus rate, atrioventricular conduction, refractoriness, and inducibility of atrial fibrillation.<Pagination><StartPage>61</StartPage><EndPage>68</EndPage><MedlinePgn>61-8</MedlinePgn></Pagination><Abstract><AbstractText Label="OBJECTIVES" NlmCategory="OBJECTIVE">This study sought to systematically investigate the interactions between the extrinsic and intrinsic cardiac autonomic nervous system (ANS) in modulating electrophysiological properties and atrial fibrillation (AF) initiation.</AbstractText><AbstractText Label="BACKGROUND" NlmCategory="BACKGROUND">Systematic ganglionated plexi (GP) ablation to evaluate the extrinsic and intrinsic cardiac ANS relationship has not been detailed.</AbstractText><AbstractText Label="METHODS" NlmCategory="METHODS">The following GP were exposed in 28 dogs: anterior right GP (ARGP) near the sinoatrial node, inferior right ganglionated plexi (IRGP) at the junction of the inferior vena cava and atria, and superior left ganglionated plexi (SLGP) near the junction of left superior pulmonary vein and left pulmonary artery. With unilateral vagosympathetic trunk stimulation (0.6 to 8.0 V, 20 Hz, 0.1 ms in duration), sinus rate (SR), and ventricular rate (VR) during AF were compared before and after sequential ablation of SLGP, ARGP, and IRGP.</AbstractText><AbstractText Label="RESULTS" NlmCategory="RESULTS">The SLGP ablation significantly attenuated the SR and VR slowing responses with right or left vagosympathetic trunk stimulation. Subsequent ARGP ablation produced additional effects on SR slowing but not VR slowing. After SLGP + ARGP ablation, IRGP ablation eliminated VR slowing but did not further attenuate SR slowing with vagosympathetic trunk stimulation. Unilateral right and left vagosympathetic trunk stimulation shortened the effective refractory period and increased AF inducibility of atrium and pulmonary vein near the ARGP and SLGP, respectively. The ARGP ablation eliminated ERP shortening and AF inducibility with right vagosympathetic trunk stimulation, whereas SLGP ablation eliminated ERP shortening but not AF inducibility with left vagosympathetic trunk stimulation.</AbstractText><AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">The GP function as the "integration centers" that modulate the autonomic interactions between the extrinsic and intrinsic cardiac ANS. This interaction is substantially more intricate than previously thought.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Hou</LastName><ForeName>Yinglong</ForeName><Initials>Y</Initials><AffiliationInfo><Affiliation>Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Clinical Medical College of Shandong University, Jinan City, Shandong, China.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Scherlag</LastName><ForeName>Benjamin J</ForeName><Initials>BJ</Initials></Author><Author ValidYN="Y"><LastName>Lin</LastName><ForeName>Jiaxiong</ForeName><Initials>J</Initials></Author><Author ValidYN="Y"><LastName>Zhang</LastName><ForeName>Ying</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Lu</LastName><ForeName>Zhibing</ForeName><Initials>Z</Initials></Author><Author ValidYN="Y"><LastName>Truong</LastName><ForeName>Kim</ForeName><Initials>K</Initials></Author><Author ValidYN="Y"><LastName>Patterson</LastName><ForeName>Eugene</ForeName><Initials>E</Initials></Author><Author ValidYN="Y"><LastName>Lazzara</LastName><ForeName>Ralph</ForeName><Initials>R</Initials></Author><Author ValidYN="Y"><LastName>Jackman</LastName><ForeName>Warren M</ForeName><Initials>WM</Initials></Author><Author ValidYN="Y"><LastName>Po</LastName><ForeName>Sunny S</ForeName><Initials>SS</Initials></Author></AuthorList><Language>eng</Language><GrantList CompleteYN="Y"><Grant><GrantID>5K23HL069972</GrantID><Acronym>HL</Acronym><Agency>NHLBI NIH HHS</Agency><Country>United States</Country></Grant></GrantList><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType><PublicationType UI="D052061">Research Support, N.I.H., Extramural</PublicationType><PublicationType UI="D013485">Research Support, Non-U.S. Gov't</PublicationType></PublicationTypeList><ArticleDate DateType="Electronic"><Year>2007</Year><Month>06</Month><Day>18</Day></ArticleDate></Article><MedlineJournalInfo><Country>United States</Country><MedlineTA>J Am Coll Cardiol</MedlineTA><NlmUniqueID>8301365</NlmUniqueID><ISSNLinking>0735-1097</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000818" MajorTopicYN="N">Animals</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D017776" MajorTopicYN="N">Autonomic Pathways</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004195" MajorTopicYN="N">Disease Models, Animal</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004285" MajorTopicYN="N">Dogs</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004558" MajorTopicYN="N">Electric Stimulation</DescriptorName><QualifierName UI="Q000009" MajorTopicYN="N">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004567" MajorTopicYN="N">Electrodes, Implanted</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D022062" MajorTopicYN="N">Electrophysiologic Techniques, Cardiac</DescriptorName><QualifierName UI="Q000379" MajorTopicYN="N">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D005725" MajorTopicYN="N">Ganglia, Autonomic</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006325" MajorTopicYN="N">Heart Atria</DescriptorName><QualifierName UI="Q000294" MajorTopicYN="N">innervation</QualifierName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006329" MajorTopicYN="N">Heart Conduction System</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="Y">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D011336" MajorTopicYN="N">Probability</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D012680" MajorTopicYN="N">Sensitivity and Specificity</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D012849" MajorTopicYN="N">Sinoatrial Node</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="received"><Year>2006</Year><Month>10</Month><Day>10</Day></PubMedPubDate><PubMedPubDate PubStatus="revised"><Year>2007</Year><Month>2</Month><Day>12</Day></PubMedPubDate><PubMedPubDate PubStatus="accepted"><Year>2007</Year><Month>2</Month><Day>27</Day></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>7</Month><Day>3</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2007</Year><Month>8</Month><Day>10</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>7</Month><Day>3</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17601547</ArticleId><ArticleId IdType="doi">10.1016/j.jacc.2007.02.066</ArticleId><ArticleId IdType="pii">S0735-1097(07)01262-4</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17601037</PMID><DateCompleted><Year>2007</Year><Month>08</Month><Day>27</Day></DateCompleted><DateRevised><Year>2018</Year><Month>12</Month><Day>19</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0869-6047</ISSN><JournalIssue CitedMedium="Print"><Issue>5</Issue><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Vestnik Rossiiskoi akademii meditsinskikh nauk</Title><ISOAbbreviation>Vestn Ross Akad Med Nauk</ISOAbbreviation></Journal>[Comparison of the efficacy and safety of electrical cardioversion and pharmacological cardioversion with nibentan in patients with persisting atrial fibrillation and flutter]. | The aim of the study was to compare the efficacy and safety of pharmacological cardioversion (PC) by nibentan, a class III antiarrhythmic agent, and electrical cardioversion (EC) in patients with persisting atrial fibrillation (AFib) and atrial flutter (AFI) receiving basic antiarrhythmic therapy. Ninety-seven patients with persisting AFib and AFI were included in the trial (45 patients constituted PC group, and 52 constituted EC group). Both groups were comparable according to basic demographic and clinical parameters as well as antiarrhythmic therapy being applied. The results of the study showed that the efficacy of PC did not differ from that of EC (86.7% and 92.3% respectively, p = 0.282). the frequency of arrhythmogenic effect did not differ between the groups either (p = 0.46). One case of non-stable ventricular tachycardia was registered in the PC group. The most significant adverse effect was bradicardia, which was registered more often in the PC group than in EC group (26.7% and 3.8%, respectively, p = 0.001). In conclusion, the efficacy and safety of PC with nibentan in patients with persisting AFib/AFI is comparable with those of EC. |
8,548 | Tachycardia-induced heart failure. | Heart failure associated with tachyarrhythmias can very often be reversed by dealing with the underlying tachyarrhythmia. Typically characterized by left ventricular dilation and subsequent systolic dysfunction, this disorder can be caused by both atrial and ventricular arrhythmias, most commonly chronic atrial fibrillation. Whereas for most cardiomyopathies there is little that can be done to reverse the progression of the disease, in tachycardia-induced heart failure the patient's often debilitating symptoms can be ameliorated. This is particularly important in the primary care setting because tachyarrhythmias, particularly atrial fibrillation, are commonly encountered. The alert physician will be able to diagnose and treat tachyarrhythmias, which can result in improvement of systolic function within weeks and often normalization within several months. |
8,549 | Does intermittent aortic cross clamping decrease the incidence of atrial fibrillation after coronary bypass surgery? | Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass grafting (CABG). AF is a vexing problem that causes morbidity, prolongs hospital stay, and increases costs. Numerous factors have been suggested to play a role in the development of AF. The aim of this study was to evaluate the effect of intermittent aortic cross clamping (IACC) compared with hypothermic cardioplegic solution (HCS) in the development of postoperative AF. We evaluated data obtained from 345 patients undergoing CABG with HCS (HCS group, n = 212) and IACC (IACC group, n = 173) between April 2004 and August 2005. Diabetes mellitus was observed more often in the HCS group (P < .05), otherwise both groups had similar preoperative characteristics including sex, age, the number of distal anastomoses, left ventricle ejection fraction, history of myocardial infarction, and use of beta-blocker medication. The only statistically significant difference between the groups was higher postoperative Ca-antagonist use in the HCS group. Rates of postoperative AF, however, were significantly lower in the IACC group (21.52%) than that in the HCS group (11.05%; P < .01). Postoperative Ca-antagonist use in the HCS group and smoking in the IACC group were independent predictors of AF after CABG. The incidence of postoperative AF after CABG with IACC was reduced compared with HCS. IACC with ventricular fibrillation may exert a counteractive effect against AF. |
8,550 | Intravenous and oral amiodarone for the prevention of postoperative atrial fibrillation in patients undergoing off-pump coronary artery bypass surgery. | Atrial fibrillation is still a frequent complication that increases morbidity after coronary artery bypass grafting. This prospective randomized study is designed to define efficacy of postoperative amiodarone prophylaxis in preventing atrial fibrillation after off-pump coronary artery bypass grafting.</AbstractText>One hundred forty-four patients who underwent elective off-pump coronary artery bypass grafting were enrolled for the study. Seventy-six patients (amiodarone group) received 5 mg/kg loading amiodarone infusion in the first postoperative hour, followed by 10 mg/kg for the first 24 hours. After 24 hours, patients received 600 mg/day amiodarone orally for 7 days and 200 mg/day until the end of the postoperative first month. Sixty-eight patients received placebo (control group).</AbstractText>Preoperative characteristics and operative variables of the patients were similar in both groups. Incidence of new-onset atrial fibrillation and maximal ventricular rate response were recorded. The incidence of new-onset atrial fibrillation (11.8% versus 26.5%) (P = .025) and maximal ventricular rate response (109 +/- 13.8 beats/min versus 124.5 +/- 13.9 beats/min) (P = .011) were significantly lower in the amiodarone group. Duration of atrial fibrillation was 17.5 +/- 8.1 hours for the amiodarone group compared with 32.7 +/- 12 hours for the control group (P = .002).</AbstractText>Postoperative intravenous amiodarone prophylaxis followed by oral amiodarone significantly reduces the incidence of atrial fibrillation after off-pump coronary artery bypass grafting and the ventricular rate during atrial fibrillation.</AbstractText> |
8,551 | Preshock phase singularity and the outcome of ventricular defibrillation. | Phase singularity (PS) is a topological defect that serves as a source of ventricular fibrillation (VF). Whether or not the quantity of preshock PS determines defibrillation outcome is unclear.</AbstractText>The purpose of this study was to test the hypothesis that the number of PSs at the time of shock is an important factor that determines the shock outcome.</AbstractText>Isolated, perfused rabbit hearts (n = 7) were optically mapped with a potentiometric dye (di-4-ANNEPS). Shocks were delivered during short (10 seconds) and long (1 minute) VF, and the outcome was classified as successful type A (immediate termination), type B (postshock repetitive responses before termination), and unsuccessful.</AbstractText>When shock strengths of 50% probability of successful defibrillation (DFT50) +/- 50 V were given in short VF, the types A and B and unsuccessful shocks were associated with a preshock PS number of 0.3 +/- 0.4, 1.4 +/- 0.3, and 1.5 +/- 0.4 (P <.01 by analysis of variance) and shock strengths of 205 +/- 77, 207 +/- 65, and 173 +/- 74 V (P <.01), respectively. When the same shocks were applied during long VF, the PS numbers were 1.7 +/- 0.5, 3.0 +/- 0.5, and 3.5 +/- 0.6, respectively (P <.01), and the shock strengths were 282 +/- 100, 283 +/- 135, and 256 +/- 126 V, respectively (P <.01). If we only analyze shocks with strength at DFT(50), the preshock PS number was still significantly different for short VF (0.6 +/- 0.5, 1.6 +/- 0.9, and 1.5 +/- 0.8; P <.05) and for long VF (1.4 +/- 0.5, 2.7 +/- 0.6, and 2.7+/-1.3; P <.05), respectively. All preshock PSs were eliminated by shocks. However, rapid repetitive activity was then reinitiated in unsuccessful and type B successful shocks but not in type A successful shocks.</AbstractText>A low number or an absence of preshock PS was associated with type A successful defibrillation. There was no difference in preshock PS numbers between unsuccessful and type B successful defibrillation.</AbstractText> |
8,552 | Eliminating right ventricular pacing may not be best for patients requiring implantable cardioverter-defibrillators. | Excessive right ventricular (RV) pacing has been associated with adverse clinical outcomes in patients receiving pacemakers or implantable cardioverter-defibrillators (ICDs). It remains uncertain how much RV pacing is clinically deleterious.</AbstractText>This retrospective analysis assessed the relationship between the amount of RV pacing and the composite of all-cause mortality and heart failure hospitalization in all patients programmed DDDR in the Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) study.</AbstractText>Seven hundred fifteen patients consistently programmed to DDDR mode throughout follow-up (mean 11.6 months) were examined. The relationship between RV pacing tier and death and heart failure hospitalization was determined and compared with patient characteristics.</AbstractText>Across the six RV pacing tiers, patients differed significantly with respect to age, clinical history of ventricular tachycardia, atrial fibrillation, and atrial flutter, and amiodarone use. When controlling for these baseline differences, the best outcome was seen in the group with RV pacing between 10% and 19% (2.8% event rate; n = 106). Increasing levels of RV pacing were generally predictive of higher event rates (death or heart failure hospitalization; P = 0.003), except for the group (n = 344) with the least amount of RV pacing (0-9%). This group exhibited poorer outcomes than otherwise expected (P = 0.016), with 8.1% of these patients experiencing an event.</AbstractText>High levels of RV pacing are associated with heart failure hospitalization and mortality in a large ICD population. However, ICD patients with some RV pacing (10%-19%) exhibit lower event rates compared with those with very low levels (0-9%), possibly due to the physiologically appropriate nature of that RV pacing.</AbstractText> |
8,553 | Optimizing implantable cardioverter-defibrillator treatment of rapid ventricular tachycardia: antitachycardia pacing therapy during charging. | Previous studies in implantable cardioverter-defibrillator (ICD) patients demonstrated the efficacy and safety of antitachycardia pacing (ATP) for rapid ventricular tachycardias (VT). To prevent shock delay in case of ATP failure, a new feature (ATP during charging) was developed to deliver ATP for rapid VT while charging for shock.</AbstractText>The purpose of this study was to determine the efficacy and safety of this new feature.</AbstractText>In a prospective, nonrandomized trial, patients with standard ICD indication received an EnTrust ICD. VT and ventricular fibrillation (VF) episodes were reviewed for appropriate detection, ATP success, rhythm acceleration, and related symptoms.</AbstractText>In 421 implanted patients, 116 VF episodes occurred in 37 patients. Eighty-four (72%) episodes received ATP during or before charging. ATP prevented a shock in 58 (69%) of 84 episodes in 15 patients. ATP stopped significantly more monomorphic (77%) than polymorphic VTs (44%, P = .05). Five (6%) episodes accelerated after ATP but were terminated by the backup shock(s). No symptoms were related to ATP during charging. In four patients, 38 charges were saved by delivering ATP before charging. Of 98 induced VF episodes, 28% were successfully terminated by ATP versus 69% for spontaneous episodes (P <.01).</AbstractText>Most VTs detected in the VF zone can be painlessly terminated by ATP delivered during charging, with a low risk of acceleration or symptoms. ATP before charging allows delivery of two ATP attempts before shock in the same time that would otherwise be required to deliver only one ATP plus a shock. It also offers potential battery energy savings.</AbstractText> |
8,554 | Usefulness of ventricular dyssynchrony measured using M-mode echocardiography to predict response to resynchronization therapy. | There are discordant data about the utility of septal-to-posterior wall motion delay (SPWMD) assessed using M-mode echocardiography to predict an improvement with cardiac resynchronization therapy (CRT). Baseline SPWMD was measured using M-mode in a parasternal short-axis view in a series of 67 patients undergoing CRT and followed up after 6 months. Heart failure was caused by coronary artery disease in 27 patients. Clinical responders were patients who were alive, had not undergone heart transplantation, and also increased the distance walked in 6 minutes by >10%. Baseline SPWMDs were mean 155 +/- 113 ms and median 135. Thirty-four patients (51%) had an SPWMD >130 ms. At 6-month follow-up, there were 17 nonresponders. At baseline, there were no significant differences between patients with SPWMD >130 or <130 ms in age, drug therapy, permanent atrial fibrillation, New York Heart Association functional class, underlying cause of cardiomyopathy, QRS duration, left ventricular (LV) ejection fraction, LV dimensions, or neurohormonal activation (norepinephrine and atrial and brain natriuretic peptide). At 6-month follow-up, baseline SPWMD was not associated with clinical response, New York Heart Association functional class, distance walked in 6 minutes, LV reverse remodeling, or neurohormonal activation. SPWMD >130 ms was also not a predictor. In conclusion, SPWMD is not a good predictor of response to CRT. |
8,555 | [Estimation of defibrillation threshold using abdominally implanted cardioverter-defibrillator with an additional defibrillation pole in a dual-coil lead endocardial defibrillation system]. | Safety of patients treated with an implanted cardioverter-defibrillator (ICD) depends on defibrillator threshold (DFT). In patients with frequent ICD interventions the high DFT influences battery life-time. The aim of the study was to compare DFT in abdominally placed ICD with an active and passive can and dual-coil endocardial leads.</AbstractText>The study involved 9 patients (4 F and 5 M, mean age 56 +/- 19 years) with previously implanted in abdominal position ICD with passive can and dual-coil defibrillation lead. In all patients DFT was measured using active and passive can ICD at the time of planed generator replacement.</AbstractText>Compared to the passive can, the abdominal active can ICD lowered DFT in 6 patients (66%), in 1 patients the DFT increased, whereas in 2 patients we observed no change in DFT. The mean DFT measured with the passive can ICD was 11.6 +/- 5.2J (5.1-20J) and with the active can was 9,3 +/- 4,5J (3-18J). The mean defibrillation resistance was 64 +/- 11W (48-84W) and 55 +/- 8W (47-70W) in passive and active can respectively. Active can ICD decreased the DFT by 20% (p = 0.049) and the defibrillation resistance by 23% (p = 0.012).</AbstractText>An abdominally positioned active can ICD with dual coil defibrillation leads allowed to lower DFT and defibrillation resistance in a majority of patients. It seems useful to replace previously implanted passive can ICDs with an active ones particularly in patients with high DFT.</AbstractText> |
8,556 | Echocardiographic features of patients with paroxysmal atrial fibrillation. | There are several risk factors for the initiation of paroxysmal atrial fibrillation (PAF) and the underlying mechanisms are multifactorial. Our study aims to explore the echocardiographic parameters that can identify in patients with PAF compared to normal subjects.</AbstractText>Eighty consecutive patients who were with PAF detected by 24-h Holter monitoring (HM) were assigned in our study. The control group (n = 80) consisted individuals with no PAF on HM. Indication for HM was palpitations at rest. All patients underwent routine echocardiographic evaluation. Patients with aortic and mitral stenosis, hyperthyroidism, and hypothyroidism were excluded from the study. Comprehensive clinical data were collected.</AbstractText>Mean age of the patients with PAF was 63 +/- 11 years and of those 42% were male subjects. There was no difference in the prevalence of hypertension in both groups. Mean left ventricular ejection fraction (LVEF) was 57 +/- 15% in PAF group and 64 +/- 2% in control subjects (p < 0.001). Mean values of left atrial (LA) diameter for PAF and control groups were 3.7 +/- 0.6 cm vs. 3.1 +/- 0.4 cm (p < 0.001), respectively. Patients with PAF had more severe valve insufficiency, higher values of mean pulmonary artery systolic pressures (PAP) (29 +/- 10 mmHg vs. 25 +/- 2 mmHg, respectively; p = 0.001) and deteriorated MV inflow velocities (E:A ratio 0.9 +/- 0.4 vs. 1.1 +/- 0.3, respectively; p = 0.008) when compared to control group. In multivariate logistic regression analysis, LA diameter predicted the development of PAF after adjusted for age and gender.</AbstractText>Our results indicate that LA diameter predicts the development of PAF.</AbstractText> |
8,557 | Self-terminating AF depends on electrical remodeling while persistent AF depends on additional structural changes in a rapid atrially paced sheep model. | The development of atrial fibrillation (AF) is associated with electrical and structural remodeling. The aim of this study was to assess the contribution of electrical and structural remodeling to the development of AF in a rapid atrially paced ovine model with and without His bundle ablation and to determine the role of the angiotensin pathway and matrix metalloproteinases in this process. Thirty-five sheep were rapidly paced in the atrium and were randomized to undergo His bundle ablation (HBA) (21 sheep; HBA sheep) or not (14 sheep; non-HBA sheep). After HBA the ventricles were paced at 80 bpm. Both groups were subdivided to receive active treatment (quinapril+losartan) or placebo. Sheep were followed for 15 weeks. Inducible AF was defined as a rapid irregular atrial rhythm lasting >1 min. Inducible AF was considered to be persistent if during further follow-up no sinus rhythm (SR) was documented anymore. The inducibility of AF with atrial tachypacing was not different between the 4 groups. On the other hand, non-HBA sheep developed persistent AF significantly earlier than HBA sheep (p=0.028). They had elevated ventricular rates, diminished atrial MMP-2, increased TIMP-2 expression, and more extensive atrial fibrosis. Active treatment in these sheep significantly lowered AT-II (p=0.018), prevented atrial fibrogenesis (p<0.001) and slowed the development of persistent AF (p=0.049). Electrical remodeling is sufficient to induce AF, while structural changes are needed for persistent AF. Fibrosis development in our model is the result of an increased expression of AT-II in combination with changes in MMP expression. Inhibition of the angiotensin pathway suppresses atrial fibrosis and the development of persistent AF. |
8,558 | Exercise testing for non-invasive assessment of atrial electrophysiological properties in patients with persistent atrial fibrillation. | Experimental studies suggest that the autonomic nervous system modulates atrial refractoriness and conduction velocity in atrial fibrillation (AF). These modulatory effects are, however, difficult to assess in the clinical setting. This study sought to non-invasively characterize in patients with persistent AF, the influence of autonomic modulation induced by exercise on atrial fibrillatory rate as marker of atrial refractoriness and to identify clinical and electrocardiographic predictors of atrial rate response.</AbstractText>In 24 patients (16 males, mean age 60 +/- 13 years) with persistent AF (16 +/- 25 months), continuous ECGs were recorded during bicycle exercise testing. Fibrillatory rate (in fibrillations per minute, fpm) was assessed at baseline and immediately after termination of exercise with spatiotemporal QRST cancellation and time-frequency analysis. Ventricular response was characterized by time-domain HRV indices. Exercise had no influence on mean fibrillatory rate (409 +/- 42 vs. 414 +/- 43 fpm, P = NS). Seven patients responded to exercise with an increase in fibrillatory rate (26 +/- 10 fpm, P < 0.001 and three with a decrease (-21 +/- 8 fpm, P < 0.001), while the remaining 14 patients did not show a response. Responders' HRV indices changed in response to exercise similarly to that of non-responders. Their baseline fibrillatory rate was, however, lower than that of non-responders (387 +/- 18 vs. 425 +/- 48 fpm, P = 0.028). No other clinical or echocardiographic variable was associated with fibrillatory rate response. Twelve weeks after cardioverson, responders were more likely to remain in sinus rhythm than non-responders (88 vs. 46 %, P = 0.04).</AbstractText>Exercise-induced autonomic activation produces changes in atrial electrophysiological properties that can be detected by time-frequency analysis. Higher baseline fibrillatory rates are associated with an impaired atrial response to exercise that suggests advanced electrical remodelling and reduced sensitivity to autonomic stimuli.</AbstractText> |
8,559 | Do small (6.6 Fr.) active and passive fixation defibrillation leads perform as well as larger sized leads? A multi-centre analysis. | The 6.6 Fr. Sprint Fidelis lead family may allow multiple lead implantation procedures with reduced risk of venous obstruction.</AbstractText>Two prospective, historically controlled, multi-centre studies were conducted in Europe (80 patients) and Canada (79 patients). The purpose was to assess the ventricular lead-related adverse events (LRAEs) and performance of the small Models 6948 and 6949 defibrillation leads, respectively, in patients with a standard indication for an ICD implant. Safety was assessed by demonstrating equivalence of the LRAE free rate at 1 month to comparable but larger leads (Models 6942, 6943, 6944, 6947and 4074). Seventy-five of 80 patients with a 6948 lead (93.8%) remained free of LRAEs. Seventy-four out of 79 patients (93.7%) with the 6949 lead remained free of LRAEs. The 95% lower confidence bounds were above the critical difference limits. Thus, safety of the Sprint Fidelis((R)) leads is similar to that of larger leads. Electrical performance through 1-month follow-up proved to be acceptable in comparison with other established leads.</AbstractText>These multi-centre studies confirm that smaller defibrillation leads offer similar safety and efficacy features to widely used larger leads; they have low LRAE rates and defibrillation thresholds, while providing the advantage of a smaller introducer size and reduced venous obstruction.</AbstractText> |
8,560 | [Heart-rate disorders: a challenge for the radiologist]. | Arrhythmia or altered heart rhythms can present with or without underlying heart disease. Most cardiopathies give rise to arrhythmias; however, arrhythmias can also be caused in previously healthy hearts by other conditions such as metabolic disorders, electrolyte imbalances, and drug use or abuse. The clinical presentation can range from asymptomatic cases discovered incidentally on routine examination to sudden death as the only clinical sign. In cases with clinical suspicion of arrhythmia, Holter and electrophysiological studies should be performed. If the condition is confirmed, associated cardiopathy must be ruled out. Echocardiography should be the first imaging test to be performed. Multidetector computed tomography (CT) and magnetic resonance imaging (MRI) have been applied to the field of cardiology more recently and are gradually acquiring specific roles with precise indications. In the study of arrhythmias, MRI is indicated in two particular areas: auricular fibrillation and arrhythmogenic right ventricular dysplasia. |
8,561 | Incidence of atrial fibrillation post-cavotricuspid isthmus ablation in patients with typical atrial flutter: left-atrial size as an independent predictor of atrial fibrillation recurrence. | Atrial fibrillation and atrial flutter often coexist. The long-term occurrence of atrial fibrillation in patients presenting with atrial flutter alone is unknown. We report the long-term follow-up in patients who underwent cavotricuspid isthmus ablation for treatment of lone atrial flutter.</AbstractText>Between January 1997 and June 2002, 632 patients underwent cavotricuspid isthmus ablation for the treatment of typical atrial flutter at the Cleveland Clinic Foundation. Three hundred sixty-three patients were included in this study and followed for a mean duration of 39 +/- 11 months. The mean duration of atrial flutter symptoms was 12 +/- 5 months. Mean left-atrial size and left-ventricular ejection fraction were 4.2 +/- 0.8 cm and 47 +/- 13%, respectively. After a mean follow-up time of 39 +/- 11 months, 13% (48 of 363) of the patients remained in sinus rhythm. Five percent (18 of 363) of patients experienced recurrence of atrial flutter only. Sixty-eight percent (246 of 363) experienced the onset of atrial fibrillation and 14% (51 of 363) experienced recurrence of atrial flutter and the new onset of atrial fibrillation. Overall, 82% (297 of 363) of the patients experienced new onset of drug refractory atrial fibrillation. Left-atrial size was a predictor of atrial fibrillation recurrence post-atrial flutter ablation.</AbstractText>At long-term follow-up, approximately 82% of patients post-cavotricuspid isthmus ablation for atrial flutter developed drug refractory atrial fibrillation. This finding suggests that elimination of atrial flutter might delay, but does not prevent, atrial fibrillation. Evidence suggests both arrhythmias may share common triggers and such patients may derive a better long-term benefit from anatomical ablative treatment of atrial fibrillation as well.</AbstractText> |
8,562 | Web-based virtual cardiac symposia: a new approach for worldwide professional medical education. | The Internet is an extremely powerful tool for the transmission of data and knowledge, and the question is whether this technology can be used effectively in continuing medical education. We present our experience with worldwide, web-based virtual symposia for practicing physicians.</AbstractText>The International Society for Holter and Noninvasive Electrocardiography (ISHNE) decided four years ago to conduct a series of cardiology-related educational activities for physicians utilizing a web-based approach. Six educational events under the format of virtual symposia were held on the Internet during the years 2002 to 2006. These Internet events included symposia on Brugada syndrome (2002), the long QT syndrome (2004), arrhythmogenic right ventricular dysplasia (2005), atrial fibrillation (2005), heart failure (2006), and sudden cardiac death (2006).</AbstractText>During the past four years, there has been a dramatic and progressive increase in the number of physician registrants, the number of countries represented, and the number of lectures downloaded with each subsequent virtual symposium. For example, during the month of October 2006, the Internet-based sudden cardiac death symposium involved 14,087 physician registrants from 120 countries with 64,939 lectures downloaded. The top lecture was downloaded 11,251 times, and over 200 e-mail questions and replies were exchanged. The average time per visit to the web site was 12.5 minutes.</AbstractText>The progressively increasing numbers of physician registrants from around the world who participated in these web-based, virtual symposia suggest that this approach is answering an unmet professional educational need. This Internet approach adds an important, new, low-cost dimension to continuing medical education.</AbstractText> |
8,563 | Characteristics, management process, and outcome of patients suffering in-hospital cardiopulmonary arrests in a teaching hospital in Hong Kong. | To examine the demographics, process indicators of adult in-hospital cardiopulmonary arrest resuscitation, and outcomes in a teaching hospital in Hong Kong.</AbstractText>Retrospective study.</AbstractText>A university-affiliated tertiary referral hospital with 997 acute adult beds in Hong Kong.</AbstractText>Those who suffered a cardiopulmonary resuscitation event, as documented in retrieved records of all in-patients during the inclusive period January 2002 to December 2005.</AbstractText>There were 531 resuscitation events; the mean (standard deviation) age of the corresponding patients was 70.7 (15.4) years. Most (83%) occurred in non-monitored areas and most (97%) were cardiopulmonary arrests. The predominant initial rhythm was asystole (52%); only 8% of patients had ventricular tachycardia/fibrillation. All the resuscitations were initiated by on-site first responders. The median times from collapse to arrival of the resuscitation team, to defibrillation, to administration of adrenaline, and to intubation were: 5 (interquartile range, 2-6) minutes, 5 (1-7) minutes, 5 (3-10) minutes, and 9 (5-13) minutes, respectively. The overall hospital survival (discharge) rate was 5%. The survival rate was higher among patients in monitored areas (9 vs 4%, P=0.046), among patients with isolated respiratory arrests (61 vs 3%, P<0.001), primary ventricular tachycardia/fibrillation arrests (13 vs 4%, P<0.001), shorter interval times from collapse to medication (1.5 vs 5 min, P=0.013), and longer interval times to intubation (12 vs 8 min, P=0.013).</AbstractText>Hospital survival after in-hospital cardiopulmonary arrests was poor. Possible strategies to improve survival include shorten time interval to defibrillation, and provision of more monitored beds.</AbstractText> |
8,564 | [Nonlinear dynamical complexity analysis of short-term heartbeat series using joint entropy]. | In this paper is reported a method using joint entropy to analyze the nonlinear dynamical complexity of short-term heart rate variability(HRV) signal. This method can effectively pick up dynamical information from the short-term heartbeat time series, reflect the dynamical complexity of heart rate variability, and so improve the quality of being covenient in clinical application. At first, the joint entropy method is demonstrated by applying it to the low-dimensional nonlinear deterministic systems such as logistic map and henon map. Then, the proposition is applied to the short-term heartbeat time series. The result shows that the method could robustly discriminate the patterns generated from healthy and pathologic states, as well as aging. Furthermore, the authors point out that decreased nonlinear dynamical complexity in the heartbeat time series with physiological aging and pathologic states is probably due to self-adjusting ability depression with aging and disease. At last, using the joint entropy method,the authors uncover nonrandom patterns in the ventricular response to atrial fibrillation. |
8,565 | A pilot study of mechanical stimulation and cardiac dysrhythmias in a porcine model of induced hypothermia. | Hypothermia is a frequent complication of cold weather exposure and/or wilderness injuries. Anecdotal reports have postulated that patients suffering from acute hypothermia are at significantly increased risk of developing lethal cardiac dysrhythmias secondary to the physical stimulation from moving and transporting patients.</AbstractText>To develop a model to attempt to determine if rough handling and sudden movement can induce lethal cardiac dysrhythmias in a controlled animal study of mild to severe hypothermia.</AbstractText>Ten anesthetized swine had continuous cardiac and invasive blood pressure (BP) monitoring. Core body temperature (CBT) was measured with an esophageal probe. Animals were secured to a backboard in a supine position for the duration of the study and their CBT was serially lowered by external cooling measures. At preset intervals (every 3 degrees C lowered from the baseline CBT of 38 degrees C), the animals were lifted via the backboard and rolled 90 degrees to the left and held for 5 seconds and then rolled to the right and held for 5 seconds. After rolling, the swine were lifted via the backboard 6 inches off the surgical table and dropped back onto the table, and after 15 seconds this was repeated at 12 inches. If no signs of dysrhythmia were noted, external cooling was continued. Data were analyzed by tests of proportion on mortality associated with hypothermia and mechanical stimulation. To determine whether hypothermia and mechanical stimulation were independent effects, a one-sided McNemar's test of matched pairs was employed.</AbstractText>No animal developed a dysrhythmia at a CBT > 25 degrees C with or without stimulation. Fifty percent of the animals developed fatal dysrhythmias (3 ventricular fibrillation, 2 asystole) with no stimulation but at CBT <or= 25 degrees C (average CBT 22.7 degrees C). Twenty percent (2/10) developed fatal dysrhythmias (ventricular fibrillation) during mechanical stimulation. For hypothermia, a binomial test of the observed proportion 0.70 (fatality during hypothermia) against a hypothetical proportion of 0 (no fatality in the absence of hypothermia) yielded P < .001 with power = 1.00. For mechanical stimulation, a binomial test of the observed proportion 0.20 (fatality from mechanical stimulation); against a hypothetical proportion of 0 yielded P < .001 with power = 1.00. The test of matched pairs yielded P < .037, indicating that the variables of mechanical stimulation and hypothermia jointly caused mortality.</AbstractText>Profound hypothermia induces fatal dysrhythmias both with and without mechanical stimulation in a swine model.</AbstractText> |
8,566 | The ratio of mitral deceleration time to E-wave velocity and mitral deceleration slope outperform deceleration time alone in predicting cardiovascular outcomes: the Strong Heart Study. | The deceleration time of early mitral inflow (E) is shortened by left ventricular chamber stiffening and prolonged by impaired relaxation. For any given rate of deceleration of early mitral inflow, a higher E-wave velocity (E) is associated with a longer deceleration time. It is not known whether deceleration time normalized for E-velocity or its inverse (deceleration slope) better predicts cardiovascular (CV) events compared with deceleration time or E-velocity alone.</AbstractText>We compared the prognostic value of deceleration time, E-velocity, deceleration time/E-velocity, and deceleration slope in 3102 American Indian participants in the Strong Heart Study, free of clinical CV disease and documented atrial fibrillation, in predicting fatal and nonfatal CV events.</AbstractText>During a mean of 8.5 +/- 2.4 years, there were 637 fatal and nonfatal CV events. After adjustment for traditional CV risk factors, deceleration time/E-velocity (adjusted hazard ratio [HR], 1.09; 95% confidence interval [CI], 1.00-1.18; P = .04 for every 0.89 msec/[cm/s] [1 + standard deviation {SD}] increase) and deceleration slope (HR, 0.91; 95% CI, 0.82-1.00; P = .01 for every 91 msec [1 + SD] increase) predicted CV events, whereas deceleration time and E-velocity did not. When participants with restrictive-type filling (n = 74) were removed from the analysis, deceleration time/E-velocity (HR, 1.10; 95% CI, 1.01-1.20; P = .03 for every 0.89 msec/[cm/s] [1 + SD] increase) and deceleration slope (HR, 0.64; 95% CI, 0.36-0.91; P = .01 for every 91 msec [1 + SD] increase) predicted CV events even more strongly.</AbstractText>In a large population-based sample with high prevalences of hypertension and diabetes, free of prevalent CV disease, deceleration time/E-velocity and deceleration slope predict CV events, whereas their components (deceleration time and E-velocity) do not. This suggests normalization of deceleration time for E-velocity or using its inverse (deceleration slope) more precisely captures prognostically significant prolongation of deceleration than does deceleration time alone.</AbstractText> |
8,567 | Late dofetilide-associated life-threatening proarrhythmia. | This report is about a 62-year old male patient with an implantable cardioverter defibrillator (ICD) for patient activated termination of atrial fibrillation who experienced dofetilide-associated ventricular tachyarrhythmias and ICD-induced ventricular fibrillation six months after the initiation of the antiarrhythmic drug therapy. |
8,568 | The pinwheel experiment revisited: effects of cellular electrophysiological properties on vulnerability to cardiac reentry. | In normal heart, ventricular fibrillation can be induced by a single properly timed strong electrical or mechanical stimulus. A mechanism first proposed by Winfree and coined the "pinwheel experiment" emphasizes the timing and strength of the stimulus in inducing figure-of-eight reentry. However, the effects of cellular electrophysiological properties on vulnerability to reentry in the pinwheel scenario have not been investigated. In this study, we extend Winfree's pinwheel experiment to show how the vulnerability to reentry is affected by the graded action potential responses induced by a strong premature stimulus, action potential duration (APD), and APD restitution in simulated monodomain homogeneous two-dimensional tissue. We find that a larger graded response, longer APD, or steeper APD restitution slope reduces the vulnerable window of reentry. Strong graded responses and long APD promote tip-tip interactions at long coupling intervals, causing the two initiated spiral wave tips to annihilate. Steep APD restitution promotes wave front-wave back interaction, causing conduction block in the central common pathway of figure-of-eight reentry. We derive an analytical treatment that shows good agreement with numerical simulation results. |
8,569 | Cognitive and neurophysiological outcome of cardiac arrest survivors treated with therapeutic hypothermia. | Cognitive deficits are common in survivors of cardiac arrest (CA). The aim of this study was to examine the effect of therapeutic hypothermia after CA on cognitive functioning and neurophysiological outcome.</AbstractText>A cohort of 70 consecutive adult patients resuscitated from out-of-hospital ventricular fibrillation CA were randomly assigned to therapeutic hypothermia of 33 degrees C for 24 hours accomplished by external cooling or normothermia. Neuropsychological examination was performed to 45 of the 47 conscious survivors of CA (27 in hypothermia and 18 in normothermia group) 3 months after the incident. Quantitative electroencephalography (Q-EEG) and auditory P300 event-related potentials were studied on 42 patients at the same time point.</AbstractText>There were no differences between the 2 treatment groups in demographic variables, depression, or delays related to the resuscitation. No differences were found in any of the cognitive functions between the 2 groups. 67% of patients in hypothermia and 44% patients in normothermia group were cognitively intact or had only very mild impairment. Severe cognitive deficits were found in 15% and 28% of patients, respectively. All Q-EEG parameters were better in the hypothermia-treated group, but the differences did not reach statistical significance. The amplitude of P300 potential was significantly higher in hypothermia-treated group.</AbstractText>The use of therapeutic hypothermia was not associated with cognitive decline or neurophysiological deficits after out-of-hospital CA.</AbstractText> |
8,570 | Explaining racial disparities in incidence of and survival from out-of-hospital cardiac arrest. | A prospective observational study of 4,653 consecutive cases of out-of-hospital cardiac arrest (OOHCA) occurring in New York City from April 1, 2002, to March 31, 2003, was used to assess racial/ethnic differences in the incidence of OOHCA and 30-day survival after hospital discharge among OOHCA patients. The age-adjusted incidence of OOHCA per 10,000 adults was higher among Blacks than among persons in other racial/ethnic groups, and age-adjusted survival from OOHCA was higher among Whites compared with other groups. In analyses restricted to 3,891 patients for whom complete data on all variables were available, the age-adjusted relative odds of survival from OOHCA among Blacks were 0.4 (95% confidence interval: 0.2, 0.7) as compared with Whites. A full multivariable model accounting for demographic factors, prior functional status, initial cardiac rhythm, and characteristics of the OOHCA event explained approximately 41 percent of the lower age-adjusted survival among Blacks. The lower prevalence of ventricular fibrillation as the initial cardiac rhythm among Blacks relative to Whites was the primary contributor. A combination of factors probably accounts for racial/ethnic disparities in OOHCA survival. Previously hypothesized factors such as delays in emergency medical service response or differences in the likelihood of receipt of cardiopulmonary resuscitation did not appear to be substantial contributors to these racial/ethnic disparities. |
8,571 | Diastolic function assessment in clinical practice: the value of 2-dimensional echocardiography. | The aim of this study was to test the hypothesis that diastolic dysfunction associated with increased filling pressures is unlikely in a structurally normal heart and to assess whether 2-dimensional echocardiography can facilitate diastolic function grading in a clinical setting.</AbstractText>Consecutive patients referred for transthoracic echocardiography received a comprehensive Doppler echocardiographic evaluation of diastolic function and measurements of left ventricular ejection fraction (EF) by biplane Simpson's method, left atrial volume index (LAVI) by area-length method, and interventricular septal thickness (IVS) from 2-dimensional images. Patients with atrial fibrillation, cardiac pacemaker, severe mitral regurgitation, or mitral prosthesis were excluded.</AbstractText>Of 187 patients, 38 had normal diastolic function and 77 had grade I; 54, grade II; and 18, grade III diastolic dysfunction. The presence of any 2-dimensional abnormality (EF < 55%, IVS > or = 14 mm, LAVI > or = 40 mL/m2) identified any diastolic dysfunction (grade I-III) with 92.6% sensitivity and 92.1% specificity. In a receiver operating characteristic analysis to predict any diastolic dysfunction, the areas under the receiver operating characteristic curve for EF, IVS, and LAVI and the sum of all 3 abnormalities were 0.69, 0.81, 0.87, and 0.95 (all P < .0001), respectively. Among all patients with at least one abnormality, the probability of diastolic dysfunction was 97.9% (138/141). Interpretation of 2-dimensional abnormalities together with the mitral inflow pattern resulted in correct diastolic function grading in 98.4% (184/187).</AbstractText>Structural abnormalities on 2-dimensional echocardiography are not only statistically associated with diastolic dysfunction, but the combination of LAVI, EF, and IVS is of practical value for diastolic function grading. The presence of any such 2-dimensional abnormality should be considered indicative of diastolic dysfunction.</AbstractText> |
8,572 | Atrio-ventricular block during left atrial flutter ablation. | We present a case of a patient treated with catheter ablation for atrial fibrillation aiming to pulmonary veins isolation. During ablation, atrial fibrillation organized into a left atrial flutter. Electroanatomic and electrophysiologic mapping revealed the anterior left atrium area between the mitral annulus and left atrium septum as a critical region for flutter ablation. After a few pulses of radiofrequency, complete atrio-ventricular block appeared. Finally, we propose pace mapping of the mitral annulus to detect left dislodgment of the compact atrio-ventricular node. |
8,573 | A model of survival following pre-hospital cardiac arrest based on the Victorian Ambulance Cardiac Arrest Register. | This study describes the epidemiology of sudden cardiac arrest patients in Victoria, Australia, as captured via the Victorian Ambulance Cardiac Arrest Register (VACAR). We used the VACAR data to construct a new model of out-of-hospital cardiac arrest (OHCA), which was specified in accordance with observed trends.</AbstractText>All cases of cardiac arrest in Victoria that were attended by Victorian ambulance services during the period of 2002-2005.</AbstractText>Overall survival to hospital discharge was 3.8% among 18,827 cases of OHCA. Survival was 15.7% among 1726 bystander witnessed, adult cardiac arrests of presumed cardiac aetiology, presenting in ventricular fibrillation or ventricular tachycardia (VF/VT), where resuscitation was attempted. In multivariate logistic regression analysis, bystander CPR, cardiac arrest (CA) location, response time, age and sex were predictors of VF/VT, which, in turn, was a strong predictor of survival. The same factors that affected VF/VT made an additional contribution to survival. However, for bystander CPR, CA location and response time this additional contribution was limited to VF/VT patients only. There was no detectable association between survival and age younger than 60 years or response time over 15min.</AbstractText>The new model accounts for relationships among predictors of survival. These relationships indicate that interventions such as reduced response times and bystander CPR act in multiple ways to improve survival.</AbstractText> |
8,574 | Revised resuscitation guidelines: adrenaline versus adrenaline/vasopressin in a pig model of cardiopulmonary resuscitation--a randomised, controlled trial. | Synergistic effects of adrenaline (epinephrine) and vasopressin may be beneficial during cardiopulmonary resuscitation. However, it is unknown whether either adrenaline alone or an alternating administration of adrenaline and vasopressin is better for restoring vital organ perfusion following basic life support (BLS) according to the revised algorithm with a compression-to-ventilation (c/v) ratio of 30:2.</AbstractText>After 4min of ventricular fibrillation, and 6min of BLS with a c/v ratio of 30:2, 16 pigs were randomised to receive either 45microg/kg adrenaline, or alternating 45microg/kg adrenaline and 0.4U/kg vasopressin, respectively.</AbstractText>Coronary perfusion pressure (mean+/-S.D.) 20 and 25min after cardiac arrest was 7+/-4 and 5+/-3mm Hg after adrenaline, and 25+/-2 and 14+/-3mm Hg after adrenaline/vasopressin (p<0.001 and <0.01 versus adrenaline), respectively. Cerebral perfusion pressure was 23+/-7 and 19+/-9mm Hg after adrenaline, and 40+/-10 and 33+/-7mm Hg after adrenaline/vasopressin (p<0.001 and <0.01 versus adrenaline), and cerebral blood flow was 30+/-10 and 27+/-11% of baseline after adrenaline, and 65+/-40 and 50+/-31% of baseline after adrenaline/vasopressin (p<0.05 versus adrenaline), respectively. Return of spontaneous circulation (ROSC) did not differ significantly between the adrenaline group (0/8) and the adrenaline/vasopressin group (3/8).</AbstractText>Adrenaline/vasopressin resulted in higher coronary and cerebral perfusion pressures, and cerebral blood flow, while ROSC was comparable.</AbstractText> |
8,575 | Comparison of rectilinear biphasic waveform with biphasic truncated exponential waveform in a pediatric defibrillation model. | To compare the rectilinear biphasic waveform with a biphasic truncated exponential waveform for pediatric defibrillation.</AbstractText>Prospective, randomized study.</AbstractText>Experimental laboratory of a university-affiliated research institute.</AbstractText>Male domestic piglets (4-24 kg).</AbstractText>Eleven piglets (4-8 kg), which represented a patient <1 yr old, and ten piglets (16-24 kg), which represented a pediatric patient between the ages of 2 and 8 yrs, were anesthetized, intubated, and mechanically ventilated. Ventricular fibrillation was induced and maintained for 30 secs, and a predetermined shock was then delivered to defibrillate. Following defibrillation, the animal was permitted to stabilize hemodynamically for 4 mins. Fifty shocks were applied to each animal using a randomization schedule based on a predetermined permutation of 50. The 50 shocks were 25 shocks for each rectilinear biphasic and biphasic truncated exponential waveforms, comprising five shocks at five energy settings. Each group of five shocks was fixed at a predetermined energy value, depending on the body weight of the animal. Dose-response curves were constructed using logistic regression. Aortic pressure, electrocardiogram, left ventricular pressure, and left ventricular pressure value of 40 mm Hg were continually measured.</AbstractText>Dose-response curves determined defibrillation thresholds at 50% (D50) and 90% (D90) probability of success. The rectilinear biphasic waveform defibrillated with <90% of the D50 and D90 energies required for a biphasic truncated exponential waveform. The rectilinear biphasic waveform also successfully defibrillated with significantly less energy per body weight and per heart weight compared with a biphasic truncated exponential waveform.</AbstractText>The rectilinear biphasic waveform has superior defibrillation performance compared with a biphasic truncated exponential waveform in a piglet defibrillation model for young children.</AbstractText> |
8,576 | [Prevalence of atrial fibrillation in the Spanish population aged 60 years or more. The PREV-ICTUS study]. | The aims of this study were to determine the prevalence of atrial fibrillation in individuals aged 60 years or more in Spain using a random sample of the population and to identify associated factors.</AbstractText>An analysis of the PREV-ICTUS study, a randomized cross-sectional population-based study of individuals aged 60 years or more, was carried out. Data on demographic variables, cardiovascular risk factors, and cardiovascular disease were obtained from medical records. The diagnosis of atrial fibrillation was based on the patient's medical history and an electrocardiogram performed during the study.</AbstractText>In the 7108 individuals studied (mean age 71.9 [7.1] years, 53.6% female), the prevalence of atrial fibrillation was 8.5% (95% confidence interval [CI] 7.9-9.2%). It was higher in males (9.3% vs 7.9% in females; P=.036) and increased from 4.2% in individuals aged 60-64 years to 16.5% in those aged 85 years or more (chi-squared test for linear trend, P< .001). Multivariate analysis showed that existing cardiovascular disease, hypertension, age, and left ventricular hypertrophy had the strongest associations with atrial fibrillation. Although there was a strong relationship between hypertension and atrial fibrillation (odds ratio 2.53, 95% CI, 1.60-4.01), no association was found between poor blood pressure control and atrial fibrillation. A weak association with diabetes mellitus was found only when arterial pressure was included in the model, but not when a diagnosis of hypertension was included.</AbstractText>In this cross-sectional population-based study of elderly individuals, the prevalence of atrial fibrillation was 8.5%, and was strongly associated with existing cardiovascular disease, hypertension, age and left ventricular hypertrophy.</AbstractText> |
8,577 | Five cases of aconite poisoning: toxicokinetics of aconitines. | Aconite poisoning was examined in five patients (four males and one female) aged 49 to 78 years old. The electrocardiogram findings were as follows: ventricular tachycardia and ventricular fibrillation in case 1, premature ventricular contraction and accelerated idioventricular rhythm in case 2, AIVR in case 3, and nonsustained ventricular tachycardia in cases 4 and 5. The patient in case 1 was given percutaneous cardiopulmonary support because of unstable hemodynamics, whereas the other patients were treated with fluid replacement and antiarrhythmic agents. The main aconitine alkaloid in each patient had a half-life that ranged from 5.8 to 15.4 h over the five cases, and other detected alkaloids had half-lives similar to the half-life of the main alkaloid in each case. The half-life of the main alkaloid in case 1 was about twice as long as the half-lives in the other cases, and high values for the area under the blood concentration-time curve and the mean residence time were only observed in case 1. These results suggest that alkaloid toxicokinetics parameters may reflect the severity of toxic symptoms in aconite poisoning. |
8,578 | The association between pneumococcal pneumonia and acute cardiac events. | Increased cardiac stress, hypoxemia, and inflammation may contribute to acute cardiac events, such as myocardial infarction (MI), arrhythmia, and/or congestive heart failure (CHF). We sought to determine the incidence of such events in patients who were hospitalized for community-acquired pneumococcal pneumonia.</AbstractText>We studied the medical records of all patients who were admitted for pneumococcal pneumonia during a 5-year period (2001-2005) to identify those who had MI, atrial fibrillation or ventricular tachycardia, or new-onset or worsening CHF at the time of hospital admission.</AbstractText>Of 170 patients, 33 (19.4%) had > or =1 of these major cardiac events. Twelve had MI, of whom 2 also had arrhythmia and 5 had new-onset or worsening CHF. Eight had new-onset atrial fibrillation or ventricular tachycardia; 6 of these also had new CHF. Thirteen had newly diagnosed or worsening CHF, without MI or new arrhythmias. Hypoxemia and anemia were prominent. Importantly, patients with concurrent pneumococcal pneumonia and cardiac events had a significantly higher mortality than those with pneumococcal pneumonia alone (P<.008). The coexistence of pulmonary and cardiac disease was often overlooked by admitting physicians who, seeking a unifying diagnosis, emphasized one diagnosis to the exclusion of the other.</AbstractText>Patients with pneumococcal pneumonia are at substantial risk for a concurrent acute cardiac event, such as MI, serious arrhythmia, or new or worsening CHF. This concurrence significantly increases mortality due to pneumonia. Admitting physicians tend to seek a unifying diagnosis, but the frequent coexistence of pneumonia and cardiac events indicates the importance of considering multiple diagnoses.</AbstractText> |
8,579 | Technical considerations for dominant frequency analysis. | Dominant frequency (DF) analysis of atrial electrograms has been used to characterize atrial fibrillation (AF). The aim of this study was to explore technical issues that may affect the estimation of local activation rate during AF using DF analysis.</AbstractText>Epicardial atrial electrograms recorded during AF from 10 dogs were used to evaluate the effects of unipolar versus bipolar recordings, bipolar electrode spacing, postrecording processing, far field ventricular depolarizations, ventricular template subtraction, and signal duration on DF analysis. Simulated electrograms were used to evaluate the effect of far field ventricular depolarizations and signal-to-noise ratio. DFs were compared with activation rates obtained by manual marking and the reproducibility of the DFs was evaluated. Bipolar electrograms were found to be preferable to unipolar electrograms. Preprocessing was a necessary step for bipolar signals, but also aided analysis of unipolar recordings. Ventricular far field depolarizations significantly affected DFs. Ventricular template subtraction helped DF analysis in signals with both minimal and significant ventricular components. A recording duration above 2 seconds was required for reliable DF measurements. Signal-to-noise ratios below 13 dB could also affect DF, particularly for signals with significant amplitude and frequency variation.</AbstractText>Various factors affect DF analysis. Proper interpretation of DF analysis requires careful evaluation of the AF signals and robust processing techniques.</AbstractText> |
8,580 | I(Ks) block by HMR 1556 lowers ventricular defibrillation threshold and reverses the repolarization shortening by isoproterenol without rate-dependence in rabbits. | The slow delayed rectifier K+ current (I(Ks)) contributes little to ventricular repolarization at rest. It is unclear whether I(Ks) plays a role during ventricular fibrillation (VF) or ventricular repolarization at rapid rates during beta-adrenergic stimulation.</AbstractText>In an in vivo rabbit model, we evaluated the effects of HMR 1556 (1 mg Kg(-1) + 1 mg kg(-1) hr(-1) i.v.), a selective I(Ks) blocker, on monophasic action potential duration at 90% repolarization (MAPD90), ventricular effective refractory period (VERP), and defibrillation threshold (DFT). In perfused rabbit hearts, the effects of HMR 1556 (10 and 100 nM) in the presence of isoproterenol (5 nM) on MAPD90 and VERP were studied at cycle lengths (CLs) 200-500 msec. In vivo, HMR 1556 prolonged MAPD90 by 6 +/- 1 msec at CL 200 msec (P < 0.01, n = 6), lowered DFT from 558 +/- 46 V to 417 +/- 31 V (P < 0.01), and decreased the coefficient of variation in the VF inter-beat deflection intervals from 8.9 +/- 0.6% to 6.5 +/- 0.4% (P < 0.05) compared with control. In perfused rabbit hearts, isoproterenol shortened MAPD90 by 5 +/- 1 msec at CL 200 msec and 11 +/- 4 msec at CL 500 msec (P < 0.05, n = 7). This shortening was reversed by HMR 1556 (P < 0.05), and both effects were rate-independent.</AbstractText>I(Ks) block increases VF temporal organization and lowers DFT, and I(Ks) that is activated following beta-adrenergic stimulation contributes to ventricular repolarization without rate dependence.</AbstractText> |
8,581 | Effects of shock polarity reversal on defibrillation threshold in an implantable cardioverter-defibrillator. | An increased defibrillation threshold (DFT) may limit the efficacy of an implantable cardioverter-defibrillator (ICD) in termination of life-threatening ventricular arrhythmias. A search for methods of decreasing DFT has been ongoing since the introduction of ICD into clinical practice.</AbstractText>To assess the effects of various shock polarities on DFT.</AbstractText>The study group consisted of 19 patients (8 females and 11 males, mean age 52+/-17 years) who received devices (Biotronik, Germany) with a single-coil defibrillation lead. In all patients the value of DFT was assessed using a normal shock polarity as well as using a reversed polarity shock, starting from the energy lower than that measured during normal DFT testing. The impedance of the defibrillation system using two different polarities was also measured. The effects of demographic and clinical parameters on defibrillation parameters were also examined.</AbstractText>When using normal shock polarity, the mean DFT value was 12+/-5 J (range 3.1-20 J) and impedance was 64+/-12 Omega. When shock polarity was reversed, the mean DFT value was 9.2+/-5.0 J (range 2-20 J) and impedance was 67+/-11 Omega. In 11 (58%) patients the polarity change caused a marked (by 37%) decrease in the mean DFT value - from 11.5+/-5.1 J to 7.2+/-3.8 J. In 5 patients DFT reduction was > or = 5 J. There was no relationship between demographic or clinical parameters and defibrillation efficacy using the two tested shock polarities.</AbstractText>The reversal of shock polarity reduces DFT in more than half of patients. In patients with a high DFT the use of reversed polarity of defibrillating impulse may reduce DFT, which widens the safety margin and makes implantation of additional leads unnecessary. Because clinical parameters have no value in predicting the effects of polarity changes on DFT, the efficacy of reversed polarity shock has to be assessed individually in each patient.</AbstractText> |
8,582 | Omega-3 fatty acids and sudden arrhythmic death. | Cardiovascular disease is the leading cause of death in developed countries. In Canada, in 1999, cardiovascular disease was responsible for 36% of all deaths. Ischemic heart disease accounts for the greatest percentage of these deaths (20% of all deaths), half of which are due to the acute effects of myocardial infarction. The other half are related to the late manifestations and complications of myocardial infarction. Once coronary arteriosclerosis has reached the point where it results in myocardial infarction, two main complications can ensue, loss of myocardial function and disturbance of cardiac rhythm. Progressive loss of myocardial pump function results in the syndrome of congestive heart failure. Abnormalities of the heart rhythm result in ventricular fibrillation, which is the direct cause of sudden death. Congestive heart failure rates have been easy to track because of the frequent need for hospitalization and we know from analysis of administrative databases that the annual rate of death from heart failure is about 2.5% in Canada. Sudden death, however most often occurs at home and without warning, making it much more difficult to quantitate its impact. However, the most conservative estimates suggest that no less than 25% of deaths in patients with a diagnosis of ischemic heart disease are due to ventricular fibrillation. |
8,583 | Ventricular long-axis function is of major importance for long-term survival in patients with heart failure. | To assess the importance of ventricular systolic and diastolic long-axis (LAX) function in comparison with short-axis (SAX) function for prediction of long-term survival in patients with heart failure.</AbstractText>Prospective epidemiological study.</AbstractText>University and county hospital.</AbstractText>Patients with idiopathic heart failure (n = 228), not older than 65 years, mean (SD) ejection fraction 44 (17)%, were investigated with echocardiography in the SAX and in the LAX basal parts of the right and left ventricle. Patients were followed up for 10 years with respect to total survival or heart transplantation.</AbstractText>Left ventricular (LV) LAX systolic amplitude was a strong risk predictor of long-term survival (p<0.001). In a multivariate Cox proportional hazard analysis, adjusting for age, gender, heart rate, systolic blood pressure, and SAX fractional shortening, LAX systolic amplitude was the only independent predictor of outcome (hazard ratio = 0.89 (95% CI 0.80 to 0.98), p = 0.02). Survival curves for each quartile of LAX systolic amplitude differentiated between mild, moderate and severe dysfunction in relation to outcome (p<0.001). There was a significant correlation between SAX and LAX ventricular function only in the lower range of LAX systolic amplitude (<6.8 mm).</AbstractText>LV LAX systolic amplitude independently predicted survival, after adjustment for clinical variables and LV SAX function. These data further emphasise the importance of the basal parts of the ventricles for ventricular function and thereby long-term outcome.</AbstractText> |
8,584 | Spontaneous gasping produces carotid blood flow during untreated cardiac arrest. | Coincident with "agonal" gasping during cardiac arrest, there are prominent increases in stroke volumes even in the absence of chest compression. In the present study, we tested the hypothesis that gasps also increase carotid blood flow (CBF) during untreated cardiac arrest.</AbstractText>The tracheas of nine domestic male pigs, weighing 39+/-2kg, were intubated and animals were ventilated mechanically. Ventricular fibrillation (VF) was induced electrically and untreated for 5min. Coincident with the onset of VF, mechanical ventilation was discontinued. The right femoral artery and vein were cannulated. Intrathoracic pressure (ITP) was measured with the aid of a balloon tipped catheter advanced into the esophagus for a distance of 35cm. A transonic flowprobe was placed around the right common carotid artery for measurement of CBF.</AbstractText>Gasps increased in frequency during the first 4min of untreated VF together with increases in CBF. The CBF produced by gasping averaged 220+/-102mL/min, which represented approximately 59% of a pre-cardiac arrest CBF. Significant increases in CBF were highly correlated with the decreases in ITP during the inspiratory phase of the gaspings (r=0.78) and with the increases in aortic pressure during the expiratory phase of the gaspings (r=0.76).</AbstractText>Spontaneous gasps produce significant increases in CBF during untreated cardiac arrest. The present study therefore confirmed beneficial effects of gasping during cardiac arrest.</AbstractText> |
8,585 | Outcomes of CPR in the presence of partial occlusion of left anterior descending coronary artery. | To develop a clinically relevant experimental model of cardiac arrest and CPR in which a partial occlusion of the left anterior descending coronary artery (LAD) is maintained during the resuscitation procedure and the initial post-resuscitation interval.</AbstractText>Ventricular fibrillation (VF) was induced by LAD occlusion with a balloon tipped catheter in 16 domestic male pigs weighing 41+/-2kg. After a 7min interval of untreated VF, the LAD balloon occlusion was deflated and the catheter withdrawn in eight animals. The LAD balloon was deflated in the remaining eight animals but the catheter was kept in place in order to maintain a partial occlusion of the LAD, which was approximately 75% of the internal lumen. CPR, including chest compressions and ventilations with oxygen, was then performed for 2min before a defibrillation attempt. Thirty minutes following successful resuscitation the LAD catheter was withdrawn in the animals with partial occlusion of the LAD.</AbstractText>In the animals that had the LAD totally unoccluded before to starting CPR, each animal was resuscitated successfully and survived for more than 72h with better neurological recovery during the initial 24h post-resuscitation than did the partially occluded group. When a partial occlusion of the LAD was maintained during CPR, six of eight animals were resuscitated and only four of these survived for 72h. A significantly greater number of electrical shocks prior to ROSC were required when a partial occlusion of the LAD was maintained during CPR. Significantly greater severity of post-resuscitation myocardial dysfunction was observed in animals resuscitated with a partial occlusion of the LAD.</AbstractText>In this model of prolonged untreated cardiac arrest, maintaining a partial occlusion of the LAD during CPR and the initial post-resuscitation interval required a greater number of shocks before ROSC, increased severity of post-resuscitation myocardial dysfunction significantly and yielded less favourable outcomes.</AbstractText> |
8,586 | Taser-induced rapid ventricular myocardial capture demonstrated by pacemaker intracardiac electrograms. | A Taser weapon is designed to incapacitate violent individuals by causing temporary neuromuscular paralysis due to current application. We report the first case of a Taser application in a person with a dual-chamber pacemaker demonstrating evidence of Taser-induced myocardial capture.</AbstractText>Device interrogation was performed in a 53-year-old man with a dual-chamber pacemaker who had received a Taser shot consisting of two barbs delivered simultaneously. Assessment of pacemaker function after Taser application demonstrated normal sensing, pacing thresholds, and lead impedances. Stored event data revealed two high ventricular rate episodes corresponding to the exact time of the Taser application.</AbstractText>This report describes the first human case of ventricular myocardial capture at a rapid rate resulting from a Taser application. This raises the issue as to whether conducted energy devices can cause primary myocardial capture or capture only in association with cardiac devices providing a preferential pathway of conduction to the myocardium.</AbstractText> |
8,587 | Hybrid epicardial and endocardial ablation of persistent or permanent atrial fibrillation: a new approach for difficult cases. | Although percutaneous epicardial catheter ablation (PECA) has been used for the management of epicardial ventricular tachycardia, the use of PECA for atrial fibrillation (AF) has not yet been reported.</AbstractText>To evaluate the efficacy and feasibility of a hybrid PECA and endocardial ablation for AF.</AbstractText>We performed PECA for AF in five patients (48.6 +/- 8.1 years old, all male, four redo ablation procedures of persistent AF with a risk of pulmonary vein (PV) stenosis, one de novo ablation of permanent [AF]) after an endocardial AF ablation guided by PV potentials and 3D mapping (NavX). Utilizing an open irrigation tip catheter, a left atrial (LA) linear ablation from the roof to the perimitral isthmus or localized ablation at the junction between the LA appendage and left-sided PVs or ligament of Marshall (LOM) was performed.</AbstractText>PECA of AF was successful in all patients with an ablation time of <15 minutes. The left-sided PV potentials were eliminated by PECA in all patients. Bidirectional block of the perimitral line was achieved in two of two patients and a left inferior PV tachycardia with conduction block to the LA was observed during the ablation in the area of the LOM in one patient. A hemopericardium developed in one patient, but was controlled successfully. During 8.0 +/- 6.3 months of follow-up, all patients have remained in sinus rhythm (four patients without antiarrhythmic drugs).</AbstractText>A hybrid PECA of AF is feasible and effective in patients with redo-AF ablation procedures and at risk for left-sided PV stenosis or who are resistant to endocardial linear ablation.</AbstractText> |
8,588 | Cerebral protection. | Ischaemic/hypoxic insults to the brain during surgery and anaesthesia can result in long-term disability or death. Advances in resuscitation science encourage progress in clinical management of these problems. However, current practice remains largely founded on extrapolation from animal studies and limited clinical investigation. A major step was made with demonstration that rapid induction of mild sustained hypothermia in comatose survivors of out-of-hospital ventricular fibrillation cardiac arrest reduces death and neurological morbidity with negligible adverse events. This provides the first irrefutable evidence that outcome can be favourably altered in humans with widely applicable neuroprotection protocols. How far hypothermic protection can be extended to global ischaemia of other aetiologies remains to be determined. All available evidence suggests an adverse response to hyperthermia in ischaemic or post-ischaemic brain. Management of other physiological values can have dramatic effects in experimental injury models and this is largely supported by available clinical data. Hyperoxaemia may be beneficial in transient focal ischaemia but deleterious in global ischaemia. Hyperglycaemia causes exacerbation of most forms of cerebral ischaemia and this can be abated by restoration of normoglycaemia. Studies indicate little, if any, role for hyperventilation. There is little evidence in humans that pharmacological intervention is advantageous. Anaesthetics consistently and meaningfully improve outcome from experimental cerebral ischaemia, but only if present during the ischaemic insult. Emerging experimental data portend clinical breakthroughs in neuroprotection. In the interim, organized large-scale clinical trials could serve to better define limitations and efficacy of already available methods of intervention, aimed primarily at regulation of physiological homeostasis. |
8,589 | Do daily threshold trend fluctuations of epicardial leads correlate with pacing and sensing characteristics in paediatric patients? | To evaluate whether the magnitude of daily ventricular pacing threshold fluctuations (Deltafluctuation) in trend graphs of stored diagrams correlate with ventricular threshold and sensing changes over time.</AbstractText>A total of 56 children received AutoCapture devices (St. Jude Medical, Sylmar, CA, USA) connected to steroid-eluting epicardial leads. Maximum lead age at study closure was 12.2 years (median 4.0). Telemetry data and daily Deltafluctuation were obtained every 6 months. Regression slope coefficients and mean values of repeated measurements were calculated for each patient's course. High daily Deltafluctuation correlated with higher pacing thresholds (rho = 0.68, P < 0.001), lower impedances (rho = -0.38, P = 0.004), and a Deltafluctuation-incline (rho = 0.34, P = 0.01) over time. Furthermore, a Deltafluctuation-incline correlated with a pacing threshold-incline (rho = 0.34, P = 0.01). No correlation was observed for ventricular sensing. Higher daily Deltafluctuation were observed if lead age was > 5 years compared with <or= 5 years (0.75 vs. 0.55 V@0.5 ms, P = 0.028).</AbstractText>High amplitudes of daily Deltafluctuation correlate with higher and increasing pacing thresholds and lower impedances. Theoretically, this results from electrode microinstability on the epicardial surface. A decrease of the steroid-eluting potency of the electrode can be hypothesized to cause higher daily Deltafluctuation beyond a lead age of 5 years. Potential implications of marked daily Deltafluctuation are short-term follow-up and lead replacement in the presence of high pacing thresholds.</AbstractText> |
8,590 | [Significance of permanent atrial fibrillation in idiopathic dilated cardiomyopathy]. | The significance of atrial fibrillation (AF) in idiopathic dilated cardiomyopathy (IDCM) remains discussed. The purpose of the study was to evaluate the clinical significance of permanent atrial fibrillation in patients with IDCM.</AbstractText>Systematic noninvasive and invasive studies including Holter monitoring, measurement of left ventricular ejection fraction (LVEF), electrophysiological study and coronary angiography were performed in 323 patients with IDCM; all patients had a left ventricular ejection fraction (LVEF)<40%. The studies were indicated for spontaneous ventricular tachycardia (VT) in 69 patients, syncope in 103 patients and nonsustained VT on Holter monitoring in 151 asymptomatic patients. Sixty-five patients were in permanent AF (group I). Remaining patients were in sinus rhythm at the time of evaluation (group II). Programmed ventricular stimulation using up to 3 extrastimuli in control state and if necessary after isoproterenol was systematic. Patients were followed 3+/-2 years.</AbstractText>Mean age was significantly older in group I (61+/-8 years) than in group II (52+/-12) (P<0.01). Syncope (31 vs 36%), spontaneous sustained VT (18 vs 23%); mean LVEF (28+/-9% vs 29+/-9%), VT induction (25 vs 35%) were similar in both groups. During the follow-up, there were no statistical differences between groups I and II concerning each event: sudden death occurred in 13 patients, 1.5% of group I patients and 5% of group II patients (NS); a death related to heart failure occurred 22 patients, 5% of group I patients and 7% of group II patients (NS); heart transplantation was performed in 13 patients, 8% of group I patients and 3% of group II patients (NS).</AbstractText>An older age is the only significant clinical factor associated with the presence of a permanent atrial fibrillation in idiopathic dilated cardiomyopathy. The presence of permanent AF does not increase the induction of a sustained ventricular tachycardia and does not affect the general prognosis of IDCM.</AbstractText> |
8,591 | External cardioversion of atrial fibrillation in patients with implanted pacemaker or cardioverter-defibrillator systems: a randomized comparison of monophasic and biphasic shock energy application. | External cardioversion (ECV) of atrial fibrillation (AF) may damage implanted pacemaker and cardioverter-defibrillator (ICD) systems. This prospective study evaluated the safety and efficacy of ECV comparing mono- to biphasic shock waveforms in patients with implanted rhythm devices.</AbstractText>Patients with pacemaker or ICD systems and an indication for ECV were randomized to receive mono- or biphasic shocks. Systems were tested immediately before and after ECV, 1 h and 1 week later with respect to device and lead integrity. Forty-four patients (71 +/- 10 years, 31 male; 29 pacemakers, 12 ICDs, three cardiac resynchronization systems) underwent ECV with antero-posterior paddle orientation (monophasic in 21 and biphasic in 23 patients). Pacing impedances were reduced immediately after ECV (atrial 402-392 ohm, P < 0.001; ventricular 517-496 ohm, P = 0.001) and returned to baseline values within 1 week. Ventricular sensing was reduced immediately after ECV (12.4-11.6 mV, P = 0.004). There was no device or lead dysfunction in any patient. ECV was successful in 42/44 patients (95%), cumulative energy was significantly lower for biphasic compared with monophasic shocks (P = 0.001).</AbstractText>ECV for AF seems to be safe and effective in patients with implanted rhythm devices.</AbstractText> |
8,592 | The potential to improve primary prevention in the future by using BNP/N-BNP as an indicator of silent 'pancardiac' target organ damage: BNP/N-BNP could become for the heart what microalbuminuria is for the kidney. | Brain natriuretic peptide (BNP) or N-terminal pro-BNP (N-BNP) now appears to be the best independent predictor of cardiovascular mortality over and above the conventional ones like blood pressure. This may be because a high BNP/N-BNP is identifying any form of asymptomatic cardiac target organ damage (TOD) [especially silent ischaemia, left ventricular hypertrophy (LVH), left atrial dilatation/atrial fibrillation (LAD/AF) and LV systolic dysfunction (LVSD)]. There are strong hints that BNP/N-BNP will also identify those who are going to develop LVH, LAD/AF, and LVSD in a few years' time. Thus, the prospects are good that BNP/N-BNP could be used to identify 'pancardiac' TOD, even when it is silent and that this information could be 'harnessed' to improve primary prevention. BNP/N-BNP could become to the heart what microalbuminuria is to the kidneys, i.e. an indicator of early, silent TOD. |
8,593 | Long-term follow-up and risk assessment of arrhythmogenic right ventricular dysplasia/cardiomyopathy: personal experience from different primary and tertiary centres. | Limited data are available on the course of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) because of the low frequency of this diagnosis. A long-term follow-up was analysed in typical ARVD/C patients from different primary and tertiary centres, and risk factors for sudden cardiac death (SCD) and end-stage heart failure were assessed.</AbstractText>A total of 313 patients (197 males) with a mean age of 44.8 +/- 16.5 years were included, with symptoms including aborted SCD (7%), ventricular arrhythmias (47%), additional chest pain (42%), syncopes (17%), and atrial arrhythmias (12%); follow-up duration was 8.5 years. The total annual mortality rate was 0.3%, from SCD in 0.2% and heart failure in 0.1%. In symptomatic or high-risk patients, the annual rate of malignant ventricular arrhythmias was 6 and 9%, respectively. In multivariate analysis, a risk factor for SCD was left ventricular dysfunction. The annual heart failure rate was low at 0.5%; four patients died, two had heart transplants and one tricuspid reconstruction. Intrathoracic cardioverter-defibrillator (ICD) therapy was initiated in 35 patients. Adequate shocks after 6-72 months were delivered in 77%; in the majority aborted sudden death with documented ventricular fibrillation and unstable ventricular tachycardia were underlying arrhythmias.</AbstractText>The clinical course of ARVD/C is characterized by a high rate of recurrent malignant ventricular arrhythmias in initially symptomatic and high-risk cases, and is uneventful in primarily asymptomatic affected individuals. The spectrum of clinical symptoms represents a warning symptom initiating the so-called 'hot phase' of the disease in many cases. ICD treatment is highly effective in cases of aborted SCD and unstable ventricular tachycardia.</AbstractText> |
8,594 | Long-term follow-up and quality of life after closure of ventricular septal defect in adults. | To study patients who underwent surgical closure of a congenital ventricular septal defect (VSD) and presenting at adult age.</AbstractText>A retrospective study was carried out of 28 patients (15 male) operated upon between 1980 and 2004. Patients were investigated by echocardiography, ECG and assessed for quality of life by a questionnaire. The indication for surgery was volume overload in 11 patients, endocarditis in 8, aortic valve regurgitation in 8 and the combination of a VSD with subvalvular aortic stenosis in 1. Follow-up was complete with a mean duration of follow-up of 13 years. There was no early or late mortality. One patient was reoperated for recurrent VSD. Twenty-five patients underwent echocardiography, which revealed a trivial residual VSD in two and mild aortic regurgitation in 10 (40%) patients. One patient was in atrial fibrillation. Health related quality of life in the dimensions cognitive functioning and sleep differed significantly from that of the general population.</AbstractText>With a relative difference in indications for closure of a VSD in adulthood, surgical closure of VSD at adult age is an adequate and safe procedure, with good results on long-term follow-up. Progression of aortic valve regurgitation is a matter of concern.</AbstractText> |
8,595 | Clinical predictors of left atrial thrombus and spontaneous echocardiographic contrast in patients with atrial fibrillation. | We sought to determine the relationship between clinical risk factors for systemic thromboembolism in patients with atrial fibrillation and the prevalence of left atrial (LA) spontaneous echocontrast (SEC) and LA thrombus (LAT).</AbstractText>Atrial fibrillation is associated with an increased risk of systemic thromboembolism. LA SEC and LAT also predict thromboembolic events. The relationship between clinical risk factors for systemic thromboembolism and prevalence of LA SEC and LAT is unknown.</AbstractText>In all, 524 patients with atrial fibrillation underwent transesophageal echocardiography between August 2000 and March 2005. Clinical risk factors for systemic thromboembolism were determined for each patient. A CHADS(2) score ranging from 0 to 6 was calculated for each patient as: congestive heart failure = 1 point; hypertension = 1 point; age 75 years or older = 1 point; diabetes mellitus = 1 point; and history of stroke including transient ischemic attack or systemic embolism = 2 points. Transesophageal echocardiography reports were reviewed for the presence of LA SEC and LAT. Univariate and multivariable models were structured to assess which clinical risk factors predicted the presence of LA SEC or LAT.</AbstractText>In a multivariable model, age 75 years or older, previous thromboembolic event, and left ventricular ejection fraction (LVEF) less than 40% predicted LA SEC, whereas LVEF less than 40% was the only predictor of LAT. LA SEC was present in 24% of patients with a CHADS(2) score of 0, but was present in 58% with a CHADS(2) score of 5 or 6 (P < .0001). LAT was present in 3% percent of patients with a CHADS(2) score of 0, but in 17% of patients with a CHADS(2) score of 5 or 6 (P = .0026).</AbstractText>Age 75 years or older, previous thromboembolic event, and LVEF less than 40% predict presence of LA SEC. LVEF less than 40% is the only multivariate predictor of LAT. The prevalence of LA SEC and LAT increases with increasing CHADS(2) score.</AbstractText> |
8,596 | A simpler cardiac arrest model in the mouse. | Delivering alternating currency (AC) to right ventricular endocardium to induce ventricular fibrillation (VF) in mice is complicated. We tried to validate whether transoesophageal AC stimulation could induce VF and how long AC stimulation had to be sustained to prevent the spontaneous cardioversion of VF in mice.</AbstractText>A pacing electrode was inserted orally into the oesophagus and AC was delivered to esophagus through the pacing electrode to stimulate the heart and induce VF in 15 mice. The incidence of VF and time of AC stimulation were recorded 4min after onset of VF cardiopulmonary resuscitation (CPR) was started.</AbstractText>VF was induced by short AC stimulation in all 15 mice. With the prolongation of AC stimulation, the incidences of spontaneous cardioversion of VF decreased whereas the incidence of pulseless electrical activity (PEA) increased accordingly. Following the termination of prolonged AC stimulation, VF occurred only in 1 of 15 mice, but PEA in 14 of 15 mice. Before CPR 1 of 15 and 12 of 15 animals remained in VF and in PEA, respectively, while 2 of 15 animals developed into asystole. After CPR, 11 of 15 animals were successfully resuscitated.</AbstractText>VF can be induced by a short period of transoesophageal AC stimulation in mice. However, prolonged AC stimulation is prone to induce PEA other than VF. Nonetheless, the development of a mouse CA model in this manner is simpler and easier, which may have practical significance for facilitating experimental investigation on CA and CPR.</AbstractText> |
8,597 | [Beating heart surgery for the patient of severe mitral regurgitation with a episode of ventricular fibrillation; report of a case].<Pagination><StartPage>500</StartPage><EndPage>503</EndPage><MedlinePgn>500-3</MedlinePgn></Pagination><Abstract><AbstractText>A 77-year-old female was admitted to our hospital with a diagnosis of severe mitral regurgitation. Cardiopulmonary revival was done by an emergent resuscitation for the ventricular fibrillation before admission. She had mild anoxic brain damage and brain magnetic resonance imaging (MRI) revealed severe brain atrophy. Chest X-ray showed severe cardiomegaly and congestion. Beating heart mitral valve replacement was planned for the prevention of reperfusion injury. A cardiopulmonary bypass was established by bicaval drainage and aortic return. The prolapse of anterior leaflet was recognized through transeptal approach after aortic clamp. We selected continuous infusion of antegrade cardioplegia for intraoperative coronary perfusion. Mitral valve replacement was done successfully. During intraoperation and postoperation, ventricular fibrillation did not occur. On-pump beating mitral valve replacement is a good procedure to prevent perioperative ventricular arrhythmia especially such the case with a decompressed myocardial function and with a preoperative episode of lethal ventricular arrhythmia necessary for cardiopulmonary resuscitation.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Toyama</LastName><ForeName>Shuji</ForeName><Initials>S</Initials><AffiliationInfo><Affiliation>Second Department of Surgery, Yamagata University School of Medicine, Yamagata, Japan.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Sawamura</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Yoshimura</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Nakashima</LastName><ForeName>K</ForeName><Initials>K</Initials></Author><Author ValidYN="Y"><LastName>Maekawa</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Minagawa</LastName><ForeName>T</ForeName><Initials>T</Initials></Author><Author ValidYN="Y"><LastName>Kuroda</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Sadahiro</LastName><ForeName>M</ForeName><Initials>M</Initials></Author></AuthorList><Language>jpn</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>Japan</Country><MedlineTA>Kyobu Geka</MedlineTA><NlmUniqueID>0413533</NlmUniqueID><ISSNLinking>0021-5252</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000368" MajorTopicYN="N">Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006332" MajorTopicYN="N">Cardiomegaly</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002315" MajorTopicYN="N">Cardiopulmonary Bypass</DescriptorName><QualifierName UI="Q000379" MajorTopicYN="Y">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D016887" MajorTopicYN="N">Cardiopulmonary Resuscitation</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D019918" MajorTopicYN="Y">Heart Valve Prosthesis Implantation</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D002534" MajorTopicYN="N">Hypoxia, Brain</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName><QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D007423" MajorTopicYN="N">Intra-Aortic Balloon Pumping</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008279" MajorTopicYN="N">Magnetic Resonance Imaging</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008944" MajorTopicYN="N">Mitral Valve Insufficiency</DescriptorName><QualifierName UI="Q000601" MajorTopicYN="Y">surgery</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014693" MajorTopicYN="Y">Ventricular Fibrillation</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2007</Year><Month>6</Month><Day>27</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17564069</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17563938</PMID><DateCompleted><Year>2007</Year><Month>07</Month><Day>10</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>20</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0869-6047</ISSN><JournalIssue CitedMedium="Print"><Issue>4</Issue><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Vestnik Rossiiskoi akademii meditsinskikh nauk</Title><ISOAbbreviation>Vestn Ross Akad Med Nauk</ISOAbbreviation></Journal>[The inheritance of premature ventricular excitation syndrome and the evolution of its clinical course according to prospective studies]. | A 77-year-old female was admitted to our hospital with a diagnosis of severe mitral regurgitation. Cardiopulmonary revival was done by an emergent resuscitation for the ventricular fibrillation before admission. She had mild anoxic brain damage and brain magnetic resonance imaging (MRI) revealed severe brain atrophy. Chest X-ray showed severe cardiomegaly and congestion. Beating heart mitral valve replacement was planned for the prevention of reperfusion injury. A cardiopulmonary bypass was established by bicaval drainage and aortic return. The prolapse of anterior leaflet was recognized through transeptal approach after aortic clamp. We selected continuous infusion of antegrade cardioplegia for intraoperative coronary perfusion. Mitral valve replacement was done successfully. During intraoperation and postoperation, ventricular fibrillation did not occur. On-pump beating mitral valve replacement is a good procedure to prevent perioperative ventricular arrhythmia especially such the case with a decompressed myocardial function and with a preoperative episode of lethal ventricular arrhythmia necessary for cardiopulmonary resuscitation.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Toyama</LastName><ForeName>Shuji</ForeName><Initials>S</Initials><AffiliationInfo><Affiliation>Second Department of Surgery, Yamagata University School of Medicine, Yamagata, Japan.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Sawamura</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Yoshimura</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Nakashima</LastName><ForeName>K</ForeName><Initials>K</Initials></Author><Author ValidYN="Y"><LastName>Maekawa</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Minagawa</LastName><ForeName>T</ForeName><Initials>T</Initials></Author><Author ValidYN="Y"><LastName>Kuroda</LastName><ForeName>Y</ForeName><Initials>Y</Initials></Author><Author ValidYN="Y"><LastName>Sadahiro</LastName><ForeName>M</ForeName><Initials>M</Initials></Author></AuthorList><Language>jpn</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>Japan</Country><MedlineTA>Kyobu Geka</MedlineTA><NlmUniqueID>0413533</NlmUniqueID><ISSNLinking>0021-5252</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000368" MajorTopicYN="N">Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006332" MajorTopicYN="N">Cardiomegaly</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002315" MajorTopicYN="N">Cardiopulmonary Bypass</DescriptorName><QualifierName UI="Q000379" MajorTopicYN="Y">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D016887" MajorTopicYN="N">Cardiopulmonary Resuscitation</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D019918" MajorTopicYN="Y">Heart Valve Prosthesis Implantation</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D002534" MajorTopicYN="N">Hypoxia, Brain</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName><QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D007423" MajorTopicYN="N">Intra-Aortic Balloon Pumping</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008279" MajorTopicYN="N">Magnetic Resonance Imaging</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008944" MajorTopicYN="N">Mitral Valve Insufficiency</DescriptorName><QualifierName UI="Q000601" MajorTopicYN="Y">surgery</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014693" MajorTopicYN="Y">Ventricular Fibrillation</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2007</Year><Month>6</Month><Day>27</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17564069</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17563938</PMID><DateCompleted><Year>2007</Year><Month>07</Month><Day>10</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>20</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0869-6047</ISSN><JournalIssue CitedMedium="Print"><Issue>4</Issue><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Vestnik Rossiiskoi akademii meditsinskikh nauk</Title><ISOAbbreviation>Vestn Ross Akad Med Nauk</ISOAbbreviation></Journal><ArticleTitle>[The inheritance of premature ventricular excitation syndrome and the evolution of its clinical course according to prospective studies].</ArticleTitle><Pagination><StartPage>9</StartPage><EndPage>12</EndPage><MedlinePgn>9-12</MedlinePgn></Pagination><Abstract>Interest for the problem of inheritance of premature ventricular excitation syndrome (PVES) has grown significantly in the recent years due to an increase in the prevalence of paroxysmal supraventricular tachycardia and atrial fibrillation in the general population. Appearance of such cardiac arrhythmias in young people makes it necessary to include PVES in diagnostic search program. At the same time, the clinical picture of the disease may change with age and appearance of various cardiovascular pathology. A prospective study including 240 patients was undertaken to study the evolution of the clinical course of PVES. A 30-year observation showed that in 88% of PVES patients the number of forms and the degree of the severity of cardiac arrhythmias tended to grow. By the end of the study the prevalence of paroxysmal supraventricular tachycardia had decreased significantly, while the number of patients with atrial fibrillation had increased. Attacks of atrial fibrillation occurred in PVES at older age than paroxysmal tachycardia, and it was observed much more often in cases where PVES was combined with other heart diseases. Thus, the studies show that paroxysms of atrial fibrillation in PVES patients occur more often in the presence of different cardiovascular diseases, and that clinical manifestations of PVES are determined by the evolution of the associated diseases as well. |
8,598 | Intramyocardial transplantation of autologous CD34+ stem cells for intractable angina: a phase I/IIa double-blind, randomized controlled trial. | A growing population of patients with coronary artery disease experiences angina that is not amenable to revascularization and is refractory to medical therapy. Preclinical studies have indicated that human CD34+ stem cells induce neovascularization in ischemic myocardium, which enhances perfusion and function.</AbstractText>Twenty-four patients (19 men and 5 women aged 48 to 84 years) with Canadian Cardiovascular Society class 3 or 4 angina who were undergoing optimal medical treatment and who were not candidates for mechanical revascularization were enrolled in a double-blind, randomized (3:1), placebo-controlled dose-escalating study. Patients received granulocyte colony-stimulating factor 5 microg x kg(-1) x d(-1) for 5 days with leukapheresis on the fifth day. Selection of CD34+ cells was performed with a Food and Drug Administration-approved device. Electromechanical mapping was performed to identify ischemic but viable regions of myocardium for injection of cells (versus saline). The total dose of cells was distributed in 10 intramyocardial, transendocardial injections. Patients were required to have an implantable cardioverter-defibrillator or to temporarily wear a LifeVest wearable defibrillator. No incidence was observed of myocardial infarction induced by mobilization or intramyocardial injection. The intramyocardial injection of cells or saline did not result in cardiac enzyme elevation, perforation, or pericardial effusion. No incidence of ventricular tachycardia or ventricular fibrillation occurred during the administration of granulocyte colony-stimulating factor or intramyocardial injections. One patient with a history of sudden cardiac death/ventricular tachycardia/ventricular fibrillation had catheter-induced ventricular tachycardia during mapping that required cardioversion. Serious adverse events were evenly distributed. Efficacy parameters including angina frequency, nitroglycerine usage, exercise time, and Canadian Cardiovascular Society class showed trends that favored CD34+ cell-treated patients versus control subjects given placebo.</AbstractText>A randomized trial of intramyocardial injection of autologous CD34+ cells in patients with intractable angina was completed that provides evidence for feasibility, safety, and bioactivity. A larger phase IIb study is currently under way to further evaluate this therapy.</AbstractText> |
8,599 | The use of atrial overdrive and ventricular rate stabilization pacing algorithms for the prevention and treatment of paroxysmal atrial fibrillation: the Pacemaker Atrial Fibrillation Suppression (PAFS) study. | The PAFS study is a randomized, multicentre investigation of the effects of third generation anti-atrial fibrillation pacemaker algorithms in patients with paroxysmal atrial fibrillation (PAF).</AbstractText>182 patients (72 +/- 9 years, 55% male) with at least three symptomatic episodes of PAF within prior 3 months resistant to two anti-arrhythmics were enrolled. A pacemaker-derived atrial fibrillation (AF) burden of 1-50% was required in the initial induction phase. Seventy-nine patients fulfilled these criteria and were randomized to four, month-long phases in a crossover design. Algorithm phases were 'rate soothing' on, 'ventricular rate stabilization' on, and 'All on', which included these two algorithms plus post-AF response. The algorithm phases were compared to 'All off' dual chamber universal mode (DDD 60) for the analysis. Forty-two percent of patients enrolled in the monitoring phase had no AF. The percentage of AF induced by premature atrial contractions (PACs) was significantly reduced by rate soothing from 25 to 17% (P < 0.05). There was no significant change in AF burden, AF episode number, quality of life, or symptoms with any algorithm (P = ns).</AbstractText>The rate-soothing algorithm by atrial overdrive pacing reduced PAC-initiated PAF. However, there was no overall change in AF burden, PAF episodes, patient symptoms, or quality of life. Forty-two percent of PAF patients did not show any AF after enrollment, suggesting that bradycardia pacing alone eliminates AF.</AbstractText> |
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