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9,000 | Commotio cordis--sudden cardiac death with chest wall impact. | Commotio cordis (CC), sudden death as a result of a blunt, often innocent-appearing chest wall blow, is being reported with increasing frequency. The clinical spectrum is diverse; however, a substantial number of cases occur in youth athletics. In events that occur during sport, victims are struck by projectiles regarded as standard implements of the game. Sudden death is instantaneous and victims are most often found in ventricular fibrillation (VF). Overall survival is poor; however, successful resuscitation can be achieved with early defibrillation. Autopsy is notable for the absence of any significant cardiac or thoracic injury. Development of an experimental model has allowed for substantial insights into the underlying mechanisms of sudden death. In anesthetized juvenile swine, induction of VF is instantaneous following chest wall blows occurring during a vulnerable window before the T wave peak. Crucial variables including the velocity of impact, impact location, and hardness of the impact object have been identified. Rapid left ventricular (LV) pressure rise following chest impact likely results in activation of ion channels via mechano-electric coupling. The generation of inward current via mechano-sensitive ion channels likely results in augmentation of repolarization and nonuniform myocardial activation, and is the cause of premature ventricular depolarizations that are triggers of VF in CC. While softer-than-standard safety baseballs reduce the risk of CC, commercially available chest protectors are ineffective in preventing CC. The development of more effective chest protectors and more widespread use of automated external defibrillators at youth sporting events are needed. |
9,001 | Bradykinin is a mediator, but unlikely a trigger, of antiarrhythmic effects of ischemic preconditioning. | Brief reversible ischemic episodes (ischemic preconditioning, IPC) protect the heart against arrhythmias during a subsequent prolonged low-flow ischemia. We have recently shown that this protection involves release of bradykinin, activation of bradykinin B2 receptors followed by opening of sarcolemmal, but not mitochondrial ATP-sensitive K+ channels. The goal of this study was to clarify a trigger and/or mediator role of bradykinin in the antiarrhythmic effects of IPC during low-flow ischemia.</AbstractText>Isolated perfused rat hearts underwent 60 minutes of low-flow ischemia induced by reducing perfusion pressure followed by 60 minutes of reperfusion. Preconditioning was induced by 2 x 5 minutes episodes of zero-flow ischemia. In yet other groups, preconditioned or non-preconditioned hearts were treated either with bradykinin (10 nmol/L) or with HOE 140 (bradykinin B2 receptor antagonist, 100 nmol/L).</AbstractText>IPC reduced the number of ventricular premature beats, as well as the incidence of ventricular tachycardia and of ventricular fibrillation during low-flow ischemia. In addition, this protection was abolished by HOE 140 given during low-flow ischemia. Pharmacological preconditioning using short bradykinin perfusion instead of IPC did not show antiarrhythmic effects. However, bradykinin administered during low-flow ischemia and reperfusion reduced the number of ventricular premature beats and the incidence of ventricular tachycardia and of ventricular fibrillation during low-flow ischemia.</AbstractText>Bradykinin is a mediator, but unlikely a trigger, of antiarrhythmic effects of IPC during low-flow ischemia.</AbstractText> |
9,002 | Cardiac arrests at the Cenotaph. | This report describes the case histories of three veterans who suffered cardiac arrests at the 2005 Cenotaph Remembrance Parade. All three were successfully resuscitated and admitted to the St Thomas' Hospital Coronary Care Unit. They had internal cardioverter defibrillators (ICDs) inserted and remain well. All three plan to attend Remembrance ceremonies this year. We review the evidence between emotional stress and arrhythmias and the updated National Institute for Health and Clinical Excellence (NICE) guidelines for ICDs. |
9,003 | Is sensible use being made of an inpatient Holter monitoring and transthoracic echocardiogram service within acute medicine? | Transthoracic echocardiograms (TTE) and 24-hour Holter recordings are commonly requested investigations for patients presenting with symptoms thought to be due to underlying cardiac pathology. The objective of this study was to audit the use of inpatient TTE and Holter monitors in acute medical patients under the care of physicians other than cardiologists within a tertiary cardiology referral centre. This was accomplished by a retrospective analysis of 4,623 TTE and 3,145 Holters reported by cardiologists between 8 October 1999 and 3 November 2005. The age range for Holter monitoring was 16-104 years, mean 70 (SD 18) years. The age range for TTE was 16-101 years, mean 68 (SD 17) years. Of the Holters performed, 69.1% were within normal limits. Atrial fibrillation/flutter was the commonest arrhythmia, found in 787 patients (25.0%). A total of 99 patients were referred to a cardiologist; 47 of these patients were permanently paced. Of the TTE requests to assess left ventricular function, 44.8% were normal. A cardiac source of embolism was found in 1.8% of requests to assess for this. TTE requests for infective endocarditis confirmed the diagnosis in 4.1% of patients. Holter investigation and TTE were commonly requested investigations; a large proportion of both, however, were within normal limits. This suggests that more consideration is required before making the request for Holter investigation and TTE, as more appropriate investigations may be available. |
9,004 | Survival after out-of-hospital cardiac arrest in Sydney, Australia. | Out-of-hospital cardiac arrest (OHCA) is a significant cause of death, but there is little published information on its incidence and outcomes in Australia.</AbstractText>This study was undertaken to determine the incidence and survival from OHCA in Sydney, New South Wales.</AbstractText>Patients listed on the Ambulance Service of NSW database as having an OHCA during the 12-month period 1 June 2004 to 31 May 2005 were matched with the NSW Registry of Births, Deaths and Marriages to determine if they had died, and how long they survived. Survival was also determined for patients aged 80 years or older, and for the presenting electrocardiograph (ECG) rhythm.</AbstractText>OHCAs were recorded for 2011 people in a population of 3.993 million. The age-standardised incidence was 52.6 events per 100,000 person-years (95% CI, 51.6-53.6). Incidence was significantly higher in older age groups. Only 24% of patients survived past the day of the OHCA. Survival for 28 days, 90 days and 1 year was 12.6%, 12.2%, and 11.5%, respectively. Survival was highest when the presentation ECG was ventricular fibrillation. Patients aged 80 years or older had lower survival rates.</AbstractText>Survival from OHCA in Sydney is low, and lower in patients aged 80 years or older. The incidence of OHCA in Sydney is similar to that in the rest of the world. Mortality occurs early after OHCA. Hence, for interventions to be effective in improving survival, they need to be targeted at the early stages of OHCA.</AbstractText> |
9,005 | Model-dependent effects of the gap junction conduction-enhancing antiarrhythmic peptide rotigaptide (ZP123) on experimental atrial fibrillation in dogs. | Abnormal intercellular communication caused by connexin dysfunction may be involved in atrial fibrillation (AF). The present study assessed the effect of the gap junctional conduction-enhancing peptide rotigaptide on AF maintenance in substrates that result from congestive heart failure induced by 2-week ventricular tachypacing (240 bpm), atrial tachypacing (ATP; 400 bpm for 3 to 6 weeks), and isolated atrial myocardial ischemia.</AbstractText>Electrophysiological study and epicardial mapping were performed before and after rotigaptide administration in dogs with ATP and congestive heart failure, as well as in similarly instrumented sham dogs that were not tachypaced. For atrial myocardial ischemia, dogs administered rotigaptide before myocardial ischemia were compared with no-drug myocardial ischemia controls. ATP significantly shortened the atrial effective refractory period (P=0.003) and increased AF duration (P=0.008), with AF lasting >3 hours in all 6-week ATP animals. Rotigaptide increased conduction velocity in ATP dogs slightly but significantly (P=0.04) and did not affect the effective refractory period, AF duration, or atrial vulnerability. In dogs with congestive heart failure, rotigaptide also slightly increased conduction velocity (P=0.046) but failed to prevent AF promotion. Rotigaptide had no statistically significant effects in sham dogs. Myocardial ischemia alone increased AF duration and impaired conduction (based on conduction velocity across the ischemic border and indices of conduction heterogeneity). Rotigaptide prevented myocardial ischemia-induced conduction slowing and AF duration increases.</AbstractText>Rotigaptide improves conduction in various AF models but suppresses AF only for the acute ischemia substrate. These results define the atrial antiarrhythmic profile of a mechanistically novel antiarrhythmic drug and suggest that gap junction dysfunction may be more important in ischemic AF than in ATP remodeling or congestive heart failure substrates.</AbstractText> |
9,006 | Loss-of-function mutations in the cardiac calcium channel underlie a new clinical entity characterized by ST-segment elevation, short QT intervals, and sudden cardiac death. | Cardiac ion channelopathies are responsible for an ever-increasing number and diversity of familial cardiac arrhythmia syndromes. We describe a new clinical entity that consists of an ST-segment elevation in the right precordial ECG leads, a shorter-than-normal QT interval, and a history of sudden cardiac death.</AbstractText>Eighty-two consecutive probands with Brugada syndrome were screened for ion channel gene mutations with direct sequencing. Site-directed mutagenesis was performed, and CHO-K1 cells were cotransfected with cDNAs encoding wild-type or mutant CACNB2b (Ca(v beta2b)), CACNA2D1 (Ca(v alpha2delta1)), and CACNA1C tagged with enhanced yellow fluorescent protein (Ca(v)1.2). Whole-cell patch-clamp studies were performed after 48 to 72 hours. Three probands displaying ST-segment elevation and corrected QT intervals < or = 360 ms had mutations in genes encoding the cardiac L-type calcium channel. Corrected QT ranged from 330 to 370 ms among probands and clinically affected family members. Rate adaptation of QT interval was reduced. Quinidine normalized the QT interval and prevented stimulation-induced ventricular tachycardia. Genetic and heterologous expression studies revealed loss-of-function missense mutations in CACNA1C (A39V and G490R) and CACNB2 (S481L) encoding the alpha1- and beta2b-subunits of the L-type calcium channel. Confocal microscopy revealed a defect in trafficking of A39V Ca(v)1.2 channels but normal trafficking of channels containing G490R Ca(v)1.2 or S481L Ca(v beta2b)-subunits.</AbstractText>This is the first report of loss-of-function mutations in genes encoding the cardiac L-type calcium channel to be associated with a familial sudden cardiac death syndrome in which a Brugada syndrome phenotype is combined with shorter-than-normal QT intervals.</AbstractText> |
9,007 | Wave similarity of human ventricular fibrillation from bipolar electrograms. | The aim of this report was to review existing techniques for assessment of directionality in fibrillation and to describe the concept of wave similarity analysis in human VF.</AbstractText>We applied a technique called wave similarity analysis to bipolar electrograms to study directionality during various rhythms (sinus rhythm, ventricular tachycardia and ventricular fibrillation) in humans. This technique uses the barycentre to determine the activation time and a similarity index is calculated using a technique described previously for AF studies.</AbstractText>We show here that using the wave similarity concept it is possible to recognize myocardial regions that are activated from multiple directions and differentiate those areas from regions that are activated by wave fronts in similar direction or at the exact mirror angle in ventricular fibrillation.</AbstractText>Wave similarity analysis provides a tool for assessing directional organization in human VF. This analysis of directional organization may have implications for the study of mechanisms of VF in the clinical arena.</AbstractText> |
9,008 | Death potentially secondary to sub-Tenon's block. | An 82-year-old ASA 2 patient underwent routine sub-Tenon's block for cataract surgery. One minute after injection of the local anaesthetic, the patient had a generalised tonic-clonic seizure and developed refractory ventricular fibrillation; subsequent resuscitation was unsuccessful. With no evidence for intravascular injection, the lack of structural brain abnormalities, and the most striking feature on post mortem examination being severe triple vessel coronary artery disease, it was concluded that this was primarily cardiac in origin; however, the possibility of brainstem anaesthesia should also be considered. |
9,009 | Adaptation of the heart to hypertension is associated with maladaptive gap junction connexin-43 remodeling. | We hypothesized that hypertension-related myocardial remodeling characterized by hypertrophy and fibrosis might be accompanied by cell-to-cell gap junction alterations that may account for increased arrhythmogenesis. Intercellular junctions and expression of gap junction protein connexin-43 were analyzed in rat heart tissues from both spontaneous (SHR) and L-NAME model of hypertension. Isolated heart preparation was used to examine susceptibility of the heart to lethal ventricular fibrillation induced by low potassium perfusion. Ultrastructure observation revealed enhanced neoformation of side-to-side type while internalization of end-to-end type (intercalated disc-related) of gap junctions prevailed in the myocardium of rats suffering from either spontaneous or L-NAME-induced hypertension. In parallel, immunolabeling showed increased number of connexin-43 positive gap junctions in lateral cell membrane surfaces, particularly in SHR. Besides, focal loss of immunopositive signal was observed more frequently in hearts of rats treated with L-NAME. There was a significantly higher incidence of hypokalemia-induced ventricular fibrillation in hypertensive compared to normotensive rat hearts. We conclude that adaptation of the heart to hypertension-induced mechanical overload results in maladaptive gap junction remodeling that consequently promotes development of fatal arrhythmias. |
9,010 | Successful radiofrequency ablation determines atrio-ventricular remodelling and improves systo-diastolic function at tissue Doppler-imaging. | Clinical, echocardiographic results and determinants of atrial fibrillation (AF) recurrence following AF ablation during mitral valve surgery (AFAMVS) were evaluated.</AbstractText>Fifty-two patients undergoing radiofrequency AFAMVS between January 2003 and December 2005, underwent serial echocardiographies with tissue Doppler imaging to assess atrio-ventricular function. Recurrence of AF, hospital readmission, episodes of congestive heart failure (CHF) were recorded. Predictors for AF-recurrence were evaluated.</AbstractText>At a 29.5+/-8.6 months of follow-up (100% complete), 78.8% patients were in sinus rhythm (SR). Freedom from AF-recurrence was 64.6+/-0.76%, from hospital readmission 88.9+/-0.47%, from CHF 91.6+/-0.63%. SR-patients demonstrated better freedom from hospital readmission (97.4 vs 60.6%; p=0.0003) and from CHF (100 vs 72.7%; p=0.008) during follow-up. At follow-up SR-patients demonstrated left atrial (preoperative 5.8+/-0.8 cm vs follow-up 5.1+/-0.9; p=0.013) and ventricular reverse remodelling (preoperative LVDd 5.7+/-1.1cm vs follow-up 5.2+/-1.1; p=0.048 - preoperative LVDs 4.0+/-1.4 vs follow-up 3.6+/-1.1; p=0.036). E/A ratio was normal in 73.1% (92.7% of SR-patients). TDI at the level of the left lateral annulus showed an improved left ventricular systole (Sm), and diastole (Em, E/Em) of SR-patients, compared with AF-patients (Sm 9.40+/-1.74 vs 7.72+/-1.5, p=0.0001; Em: 10.45+/-1.98 vs 7.68+/-0.72, p=0.001; E/Em: 0.07+/-0.02 vs 0.10+/-0.04, p=0.0001). Large preoperative atrial diameter (OR=5.81; p=0.002), preoperative NYHA-IV (OR=3.55; p=0.001), high diuretics at discharge (OR=1.27; p=0.03), tricuspid insufficiency at follow-up (OR=2.31; p=0.02) were independent predictors of AF-recurrence.</AbstractText>Radiofrequency AFAMVS achieves 78.8% of SR recovery. Maintenance of SR improves clinic, haemodynamic and echocardiographic endpoints. Pre- and post-operative cardiac failure is the main determinant of AF-recurrence.</AbstractText> |
9,011 | Association of delay to first intervention with return of spontaneous circulation in a swine model of cardiac arrest. | No single drug improves survival after cardiac arrest, despite success in animal studies. We sought to determine the duration of circulatory arrest after which maximal drug treatment and a rescue shock would fail to achieve return of spontaneous circulation (ROSC).</AbstractText><AbstractText Label="DESIGN/SUBJECTS" NlmCategory="METHODS">Retrospective analysis of 271 swine (20-30 kg) resuscitation attempts during ventricular fibrillation. Protocols were divided into five categories: immediate countershock, cardiopulmonary resuscitation (CPR) with standard-dose drugs, CPR alone, CPR and high-dose epinephrine (CPR+HDE) (0.1 mg/kg), and CPR with a drug cocktail (CPR+DC) of propanolol (1 mg), epinephrine (adrenaline) (0.1 mg/kg) and vasopressin (40IU). Time to first CPR, time to first drug administration, time to first shock, and protocol were examined as predictors of ROSC using logistic regression with Hosmer-Lemeshow test of fit. Probability of ROSC was calculated from logistic curves.</AbstractText>ROSC occurred in 119 of the 271 swine (44%). Time to first drug and the CPR+DC group were predictors of ROSC. Time to first CPR, the CPR+DC group, and the CPR+HDE group were also predictors of ROSC. Time to first rescue shock, the CPR+DC group, and the CPR+HDE groups were predictors of ROSC. In the CPR+DC group, 50% ROSC occurred at a first CPR time of 13.4 min, first drug time of 14.1 min and first rescue shock time of 17.5 min.</AbstractText>Pre-shock delivery of CPR+DC increases the likelihood of ROSC, and reaches 50% with a time of drug delivery of 14.1 min. ROSC rates of 50% may be achievable using an optimized resuscitation in experimental CPR.</AbstractText> |
9,012 | The impact of manual defibrillation technique on no-flow time during simulated cardiopulmonary resuscitation. | Rapid defibrillation is the most effective strategy for establishing return of spontaneous circulation following cardiac arrest due to ventricular fibrillation. The aim of this study is to measure the delay due to of charging the defibrillator during chest compression in an attempt to reduce the duration of the pre-shock pause in between cessation of chest compressions and shock delivery as advocated by the American Heart Association (AHA) guidelines compared to charging the defibrillator immediately following rhythm analysis without resuming chest compressions as recommended by the European Resuscitation Council (ERC).</AbstractText>This was a randomised controlled cross over trial comparing pre-shock pause times when defibrillation was performed on a manikin according to the AHA and ERC guidelines using paddles and hands free defibrillation systems.</AbstractText>The pre-shock pause between cessation of chest compression and shock delivery was significantly different between techniques (Friedman test, P<0.0001). ERC paddles technique had the greatest pre-shock pause (7.4 s [6.7-11.2]) followed by ERC hands free (7.0 s [6.5-8.5]) and AHA paddles (1.6 s [1.1-2.3]). AHA hands free took the least amount of time (1.5 s [0.8-1.5]). Extrapolating these data to older defibrillators with longer charge times saw pre-shock pause intervals of 9 s (Codemaster XL) and 12 s (Lifepak 20) with the ERC approach.</AbstractText>This study demonstrated clinically significant delays to defibrillation by analysing and charging the defibrillator without performing concurrent chest compressions. In a simulated scenario, charging the defibrillator whilst performing chest compressions was perceived as safe and significantly reduced the pre-shock pause between cessation of chest compression and shock delivery.</AbstractText> |
9,013 | Hypertrophic cardiomyopathy: the importance of arrhythmic events in patients at risk for sudden cardiac death. | To evaluate, in patients with hypertrophic cardiomyopathy and risk for SCD who underwent implantable cardioverter-defibrillator (ICD) implantation: a- the occurrence of arrhythmic events; b- the occurrence of clinical events and their correlation with arrhythmic events; c- the occurrence of ICD shock therapy and clinical and functional correlations; d- clinical and functional predictors of prognosis.</AbstractText>Twenty six patients with hypertrophic cardiomyopathy and risk factors for SCD undergoing ICD implantation from May, 2000 to January, 2004 (mean follow-up = 20 months) were studied. Fourteen patients (53.8%) were females and the mean age was 42.7 years. ICD was indicated for primary prevention of sudden cardiac death in 16 patients (61.5%), and for secondary prevention in 10 patients (38.5%). Twenty patients (76.9%) presented syncope prior to ICD implantation; half of them were related to ventricular fibrillation or sustained ventricular tachycardia, 15 (57.7%) had a history of familial sudden death, 12 patients (46.2%) had nonsustained ventricular tachycardia on the 24-hour Holter monitoring, and five (19.2%) had an interventricular septal thickness greater than 30 mm.</AbstractText>Four shock therapies were recorded by the ICD in potentially lethal arrhythmias (three patients with sustained ventricular tachycardia and one patient with ventricular fibrillation) during the follow-up. One death occurred, probably due to a thromboembolic stroke. Four patients had recurrence of syncope with no arrhythmic event recorded by the ICD. The statistical analysis showed a significant difference in early ICD shock therapy in patients whose interventricular septal thickness was greater than 30 mm.</AbstractText>1- occurrence of arrhythmic events in 50% of the patients; most of them (62%) were ventricular tachycardia, whether sustained (31%) or nonsustained (31%); in the remaining patients paroxysmal supraventricular tachycardia was observed. 2- recurrent syncope in the minority of the patients (16%), however not associated with the presence of arrhythmic events. 3- the presence of an interventricular septal thickness greater than 30 mm in the echocardiogram was associated with early shock therapy (p = 0.003). 4- absence of clinical or functional predictors.</AbstractText> |
9,014 | The signal-averaged electrocardiogram of atrial activation in patients with or without paroxysmal atrial fibrillation. | To analyze the parameters of the time domain P-wave signal-averaged electrocardiogram (P-SAECG) and compare them with the P-wave duration on the conventional electrocardiogram (P on ECG) as well as the left atrium diameter (LAD) and left ventricular ejection fraction (EF) obtained on the echocardiogram in order to evaluate patients with paroxysmal atrial fibrillation (PAF).</AbstractText>One hundred and eighty-one patients were included in the study: 117 with confirmed PAF and 64 without PAF. The P-SAECG parameters used were: the filtered P-wave duration (FPD), the root mean square (RMS) voltages in the last 40, 30 and 20 ms of the filtered P-wave (RMS 40, RMS 30 and RMS 20), the root mean square voltage of the filtered P-wave potentials (RMS P), the integral of the potentials during the filtered P-wave (Integral P) and the filtered P-wave late potential durations below 3 microV (PL<3).</AbstractText>The parameters that presented significant statistical differences between the groups were: FPD, RMS 40, 30 and 20, PL<3, P on ECG and LAD. The ROC curve calculations demonstrated the best cut-off points and performance estimates for each parameter: sensitivity, specificity, area under the curve and p-value (p).</AbstractText>The time domain P-SAECG proved to be a superior method to identify patients with paroxysmal atrial fibrillation than the conventional electrocardiogram and echocardiogram.</AbstractText> |
9,015 | Autonomic modulation of electrical restitution, alternans and ventricular fibrillation initiation in the isolated heart. | Abnormal autonomic nerve activity is a strong prognostic marker for ventricular arrhythmias but the mechanisms underlying the autonomic modulation of ventricular fibrillation (VF) initiation are poorly understood. We examined the effects of direct sympathetic (SS) and vagus (VS) nerve stimulation on electrical restitution, alternans and VF threshold (VFT) in a novel isolated rabbit heart preparation with intact dual autonomic innervation.</AbstractText>Monophasic Action Potentials (MAPs) were recorded from a left ventricular epicardial site on innervated, isolated rabbit hearts (n=16). Standard restitution, effective refractory period (ERP), electrical alternans and VFT were measured at baseline and during SS and VS separately.</AbstractText>The restitution curve was shifted downwards and made steeper with SS whilst VS caused an upward shift and a flattening of the curve. The maximum slope of restitution was increased from 1.30+/-0.10 at baseline to 1.86+/-0.17 (by 45+/-12%, P<0.01) with SS and decreased to 0.69+/-0.10 (by 51+/-6%, P<0.001) with VS. ERP was decreased from 127.3+/-2.5 ms to 111.8+/-1.8 ms with SS (by 12+/-2%, P<0.001) and increased to 144.0+/-2.2 ms with VS (by 13+/-2%, P<0.001). VFT was decreased from 4.7+/-0.6 mA to 1.9+/-0.5 mA with SS (by 64+/-5%, P<0.001) and increased to 8.7+/-1.1 mA with VS (by 89+/-14%, P<0.0005). There was a significant inverse relationship between the maximum slope of restitution and VFT (r=-0.63, P<0.0001). When compared with baseline, SS caused electrical alternans at longer pacing cycle lengths (139.0+/-8.4 vs. 123.0+/-7.8 ms, P<0.01) with greater degree of alternans (32.5+/-9.9 vs. 15.4+/-3.2%, P<0.05). It also caused a wider range of cycle lengths where alternans occurred (53.0+/-6.2 vs. 41.0+/-7.0 ms, P<0.05) whilst vagus nerve stimulation shortened this range (33.0+/-7.3 ms, P<0.001).</AbstractText>Sympathetic stimulation increased maximum slope of restitution and electrical alternans but decreased ERP and VF threshold whilst vagus nerve stimulation had opposite effects. The interaction between action potential duration and beat-to-beat interval may play an important role in the autonomic modulation of VF initiation.</AbstractText> |
9,016 | [The efficacy and safety of antithrombotic therapy with warfarin in nonrheumatic atrial fibrillation]. | To identify the optimal intensity of anticoagulation with warfarin in patients with nonvalvular atrial fibrillation by studying the relation between the thromboembolic and hemorrhagic events.</AbstractText>Nonvalvular atrail fibrillation patients randomized to receive adjusted-dose warfarin [international normalized ratio (INR) 2.0 to 3.0] were included. The initial dose of warfarin was 2 mg and the dose was then adjusted to target at INR 2.0-3.0. Thromboembolic events and bleeding events were identified during follow-up.</AbstractText>Of the 335 patients, 204 (60.9%) were male. Mean age was (62.6 +/- 10.3) years. Sixty-six percent of all the patients had at least one risk factor for thromboembolism. The median follow-up period was 19 months (range 2-24 months). Among the 3482 INRs measured during the study, 2378 were in the target range. Of the 19 thromboembolic events occurred during warfarin therapy, 15 occurred with INR less than 2.0. The independent risk factors for thromboembolic events during warfarin therapy were age > 75 years, history of stroke, left ventricular ejection fraction (LVEF) < 0.40 and INR > 2.0. The incidence of bleeding events were 6.9%, including 5 cases (1.5%) of minor bleeding and 18 cases (5.4%) of major bleeding. The independent risk factors for the hemorrhage in warfarin treatment are age > 75 years, systolic blood pressure > or = 160 mm Hg, elevated serum creatinine level INR > 3.0. INR of 2.0 to 3.0 was associated with the lowest combined rate of bleeding and thromboembolism.</AbstractText>INR > 3.0 should be avoided to minimize the bleeding complications. Under intense monitoring, adjusted-dose warfarin (INR 2.0 - 3.0) is effective and safe for the moderate to high risk nonvalvular atrial fibrillation patients.</AbstractText> |
9,017 | Preclinical cardio-safety assessment of torsadogenic risk and alternative methods to animal experimentation: the inseparable twins. | The last decade has been marked by the withdrawal from the market of several medicines whose use in patients has been associated with the development of torsade de pointes (TdP), a potentially life-threatening polymorphic tachycardia. In a few cases, TdP can degenerate into ventricular fibrillation and lead to sudden death, thus constituting a real problem of public health. The recently finalized ICH S7B guideline defines the prolongation of the QT interval on the electrocardiogram as the best biomarker for predicting the torsadogenic risk of a given compound. However, a growing body of evidence suggests that drugs' torsadogenic potential may not necessarily be proportional to their ability to prolong the QT interval. It is a dynamic combination of multiple predisposing factors and components rather than a single particular event that can trigger this particular tachycardia. Following recommendations of the guideline, pharmaceutical companies have intensively implemented methodologies to assess the possible risk of QT prolongation and TdP in humans. The main problem in cardiac safety pharmacology is how best to combine the capabilities of different methodologies with their strengths and limitations in order to detect the potential of one molecular entity to induce a lethal arrhythmia of very low clinical incidence. This publication will review the current methodologies, focusing on the alternative methods to animal experimentation, including an overview of cardiac modeling. |
9,018 | Brugada syndrome unmasked by pneumonia. | A 69-year-old white woman presented at our emergency room with right-side pleuritic chest pain, fever, and tachycardia. Results of the physical examination, routine laboratory tests, and chest radiography were unexceptional. An electrocardiogram showed ST elevation in leads V(1) through V(3) with T-wave inversion. Because of the chest pain and the ST elevation, the patient underwent emergency cardiac catheterization, which showed no coronary artery stenosis. A computed tomographic scan of the chest showed pulmonary infiltration in the right middle lobe and the lingula of the left upper lobe; pneumonia was diagnosed, and appropriate antibiotic therapy was started. The electrocardiographic changes met the criteria for type-1 Brugada pattern. Brugada syndrome is an arrhythmogenic disease caused in part by mutations in the cardiac sodium channel gene SCN5A. When the sodium current is disrupted, the outward transient current at the end of phase 1 of the action potential becomes unopposed. This creates a voltage gradient between the epicardium and endocardium, especially in the right ventricular wall, which leads to J-point elevation in leads V(1) through V(3). Fever exaggerates this defect in sodium channels. In our patient, the pleuritic chest pain was caused by the pneumonia, and the ST elevation was probably related to Brugada syndrome, unmasked by the febrile episode. Brugada syndrome can be associated with ventricular tachycardia or fibrillation; the only treatment proven to prevent sudden death is placement of an implantable cardioverter defibrillator, which is recommended in symptomatic patients or in those with ventricular tachycardia induced during electrophysiologic studies. |
9,019 | Uncorrected tetralogy of Fallot in an 86-year-old patient. | This report describes the presentation and evaluation of an elderly man with uncorrected tetralogy of Fallot. The patient had remained fairly asymptomatic for much of his life. He presented to the hospital at age 86 with new-onset atrial fibrillation with rapid ventricular response and a non-ST-segment elevation myocardial infarction. Transthoracic and transesophageal echocardiography revealed infundibular pulmonic stenosis with a ventricular septal defect, overriding aorta, and right ventricular hypertrophy, findings consistent with unrepaired tetralogy of Fallot. Severe right ventricular pressure overload was also present. Coronary angiography revealed nonobstructive coronary artery disease. It was felt that the rapid atrial fibrillation resulted in right ventricular subendocardial ischemia that improved following restoration of sinus rhythm. After a systematic literature search, the authors believe this case represents the oldest reported patient with the diagnosis of uncorrected tetralogy of Fallot and serves as an example of a well-balanced congenital shunt. |
9,020 | Functional capacity after traditional Chinese medicine (qi gong) training in patients with chronic atrial fibrillation: a randomized controlled trial. | Evidence indicates that low energy expenditure protocols derived from traditional Chinese medicine may benefit patients with cardiac impairment; therefore, the authors carried out a randomized controlled trial to test a 16-week medically assisted qi gong training program for the physical rehabilitation of patients with stable chronic atrial fibrillation and preserved left ventricular function. Functional capacity variation was evaluated using the 6-minute walk test, which was performed at baseline, at the end of the intervention, and after 16 weeks. Thirty men and 13 women (mean age, 68+/-8 years) were randomized to the intervention protocol or to a wait-list control group. Qi gong training was well tolerated and, compared with baseline, trained patients walked an average 114 meters more (27%) at the end of treatment (P<.001) and 57 meters more (13.7%) 16 weeks later (P=.008). Control subjects showed no variation in functional capacity. These results seem promising and deserve confirmation with further research. |
9,021 | The effect of successful electrical cardioversion on left ventricular diastolic function in patients with persistent atrial fibrillation: a tissue Doppler study. | Changes in mitral inflow and pulmonary venous flow after electrical cardioversion (ECV) in patients with persistent atrial fibrillation (AF) were showed in many former studies. In our study we investigated the effects of ECV on diastolic parameters by using tissue Doppler imaging (TDI) in patients with persistent AF.</AbstractText>Forty-one (24 women) consecutive patients underwent successful elective ECV for nonvalvular persistent AF, and maintained sinus rhythm for 1 month were enrolled to the study. Transthoracic echocardiography was applied to all patients before, 24 hours after and 1 month after ECV. Mitral annular TDI parameters were also measured with mitral inflow, pulmonary venous flow, and other standard echocardiographic measurements.</AbstractText>No differences in peak myocardial early velocity (Em), deceleration time of Em, and myocardial isovolumic relaxation time measured from mitral lateral annulus before, 24 hours after, and one month after ECV were found. Peak myocardial late velocity measured 24 hours after ECV increased significantly at the end of 1 month.</AbstractText>There were not any changes in LV diastolic function except restoration of atrial mechanical contraction following ECV in patients with persistent AF.</AbstractText> |
9,022 | Risk factors for ischemic stroke: electrocardiographic findings. | Standard 12-lead electrocardiography is a routine and mandatory cardiovascular examination in the evaluation of stroke patients. This study investigates the relationship of electrocardiography findings and first-ever ischemic stroke.</AbstractText>This hospital-based case-control study consisted of 238 consecutively hospitalized cases of first-ever ischemic stroke and 238 healthy age- and sex-matched control subjects. Multivariate logistic regression analyses were performed to evaluate the risk factors and electrocardiography findings.</AbstractText>Atrial fibrillation [odds ratio (OR) = 6.8, 95% confidence interval (CI) =1.90-24.45], myocardial ischemic change (OR = 5.0, 95% CI = 2.22-11.06), left ventricular hypertrophy (OR = 3.9, 95% CI = 2.02-7.39) and sinus bradycardia (OR = 0.37, 95% CI = 0.18-0.79) were significantly related with first-ever ischemic stroke.</AbstractText>Electrocardiography findings of atrial fibrillation, myocardial ischemic change and left ventricular hypertrophy as risk factors for ischemic stroke were similar to those from other studies. Additional studies are needed to assess the role of sinus bradycardia for ischemic stroke, which was less common in patients with stroke than in controls.</AbstractText> |
9,023 | Compromising bradycardia: management in the emergency department. | Bradycardia may represent a serious emergency. The need for temporary and permanent pacing is unknown.</AbstractText>We analysed a registry for the incidence, symptoms, presenting rhythm, underlying mechanism, management and outcome of patients presenting with compromising bradycardia to the emergency department of a university hospital retrospectively during a 10-year period.</AbstractText>We identified 277 patients, 173 male (62%), median age 68 (IQR 58-78), median ventricular rate 33 min(-1) (IQR 30-40). The leading symptoms were syncope [94 (33%)], dizziness [61 (22%)], collapse [46 (17%)], angina [46 (17%)] and dyspnoea/heart failure [30 (11%)]. The initial ECG showed high grade AV block [134 (48%)], sinus bradycardia/AV block [46 (17%)], sinuatrial arrest [42 (15%)], bradycardic atrial fibrillation [39 (14%)] and pacemaker-failure [16 (6%)]. The underlying mechanisms were primary disturbance of cardiac automaticity and/or conduction [135 (49%)], adverse drug effect [58 (21%)], acute myocardial infarction [40 (14%)], pacemaker failure [16 (6%)], intoxication [16 (6%)] and electrolyte disorder [12 patients (4%)]. In 107 (39%) patients bed rest resolved the symptoms. Intravenous drugs to increase ventricular rate were given to 170 (61%) patients, 54 (20%) required additional temporary transvenous/transcutaneous pacing. Two severely intoxicated patients could be stabilised only by cardiopulmonary bypass. A permanent pacemaker was implanted in 137 patients (50%). Mortality was 5% at 30 days.</AbstractText>In our cohort, about 20% of the patients presenting with compromising bradycardia required temporary emergency pacing for initial stabilisation, in 50% permanent pacing had to be established.</AbstractText> |
9,024 | [Implantable cardioverter defibrillator: an update]. | Automatic implantable cardioverter defibrillator is now a well established therapy to prevent sudden cardiac death. In secondary prevention (patients with a previous cardiac arrest) defibrillator can be considered as a class I indication, if there is no transient or reversible cause. The level of proof is A. in primary prevention the defibrillator is indicated in coronary artery disease patients with or without symptoms of mild to moderate heart failure (NYHA II or III), an ejection fraction lower than 30 %, measured at least one month after a myocardial infarction and 3 months after a revascularisation, surgery or angioplasty (level of proof B). It is also indicated in symptomatic spontaneous sustained ventricular tachycardias with underlying heart disease (level of proof B), in patients with spontaneous sustained ventricular tachycardia, poorly tolerated, without underlying heart disease for which pharmacological treatment or ablation can not be performed or failed (level of proof B). Finally it is also indicated in patients with syncope of unknown cause with sustained ventricular tachycardia or inducible ventricular fibrillation, with an underlying heart disease (level of proof B). The guidelines proposed by the different societies have also proposed class IIa recommendations which are the following: coronary artery disease patients with left ventricular dysfunction (ejection fraction between 31 or 35 %) measured at least one month after a myocardial infarction and 3 months after a revascularisation with an inducible ventricular arrhythmia. It can be also indicated in idiopathic dilated cardiomyopathies with an ejection fraction lower than 30% and NYHA class II or III. It can be also indicated in familial or inherited conditions with a high risk of sudden cardiac death by ventricular fibrillation without any other efficient known treatment and finally in heart failure patients remaining symptomatic, in class III or IV NYHA, with an optimal medical therapy, an ejection fraction lower than 35 % and a QRS complex duration higher than 120 ms: in this case it is an indication of cardiac resynchronization therapy device associated to the defibrillator. All these class IIa indications have a level of proof B. |
9,025 | Reversible cardiomyopathy. | We report a case of reversible dilated cardiomyopathy, in a middle-aged male. The patient presented with severe left ventricular dysfunction and atrial fibrillation. Inspite of vigorous medical therapy there was only mild clinical improvement. Subsequently laboratory test results diagnosed it as hyperthyroidism and then specific thyrostatic treatment was added. There was a prompt clinical and hemodynamic improvement in the form of reversal of left ventricular dysfunction and achievement of sinus rhythm at the end of two weeks. |
9,026 | [Cardiac resynchronization therapy in patients with permanent atrial fibrillation--with or without atrial lead?]. | A 59-year-old patient received a biventricular defibrillator for cardiac resynchronization therapy (CRT) due to severe heart failure and a left bundle branch block. He had suffered from mitral stenosis and had received valve replacement 16 years earlier. Because he had permanent atrial fibrillation since that time, no atrial lead was implanted. His symptoms improved with CRT until he received adequate shock therapy for a rapid ventricular tachyarrhythmia. After that his symptoms deteriorated again severely. The ECG recorded during an unscheduled follow-up visit 1 week after the shock explains the reason. |
9,027 | Radiofrequency current catheter ablation of accessory atrioventricular pathways. | The purpose of this study was to evaluate the safety and efficacy of a radiofrequency catheter ablation in the patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory atrio ventricular connection.</AbstractText>During a 45 month period (1st January 2002 until 30th September 2005) 373 consecutive patients underwent electrophysiological study in our electrophysiological lab at the Institute for Heart Diseases. Of all the patients 171 (45.8%) were ablated for junction depend tachycardia. Ninety-five patients had undergone ablation of atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentry tachycardia (AVRT) with accessory pathway (AP) 76 patients. Ablation of the atrioventricular node (AVN) was performed in 59 patients, because of uncontrolled atrial fibrillation with implantation of pacemakers. Ablation was successful in 206 patients (89.3%), partial successful was achieved in 21 patient (9.4%), and no successful only in 3 patients (1.3%). Ablation successful outcome rate was 98.7% (without clinical supraventricular arrhythmia in the follow up period until September 2005). There was a need for performing a re-do ablation in 11 patients (4.8%). A complication occurred in 8 patients, 4.9% (only one major complication, complete atrioventricular block with narrow QRS complex in the AVNRT group). In the group with accessory pathways (atrio ventricular reentry tachycardia (AVRT), there were 76 patients, 28 without delta way on the electrocardiogram (concealed accessory pathways), 47 patients were with open form of accessory pathways, with delta way on EKG (Wolff-Parkinson-White syndrome) and only in one patient with accessory pathway between right atrio and right bundle branch (Mahaim form of concealed accessory pathway). In two patients with AVRT, another circle movement tachycardia was found after the ablation of the accessory pathways, bystander arrhythmia of AVNRT:</AbstractText>The success and safety of catheter accessory pathway ablation is so great that we recommend this nonpharmacological approach as an initial option to any patient with AVRT who has recurrent symptomatic arrhythmias.</AbstractText> |
9,028 | [The effects of intracoronary infusion of bone marrow mononuclears on myocardial contractility]. | The effects of intracoronary infusion of bone marrow mononuclears (BMM) on myocardial contractility after myocardial infarction (MI) was studied in 16 post-infarction patients. The intracoronary infusion of autologic BMM during the subacute period of MI did not have a significant effect on myocardial contractility, the functional class of chronic heart failure, physical tolerance, and quality of life evaluated three and six months after the transplantation. Intracoronary BMM transplantation did not provoke ventricular tachycardia or ventricular fibrillation. BMM transplantation into an infarcted myocardium did not exacerbate coronary heart disease in post-infarction patients. |
9,029 | [Morgagni-Adams-Stokes after adenosine injection in a patient with WPW syndrome--a case report]. | A case of a 16-year-old girl with left sided accessory pathway is presented. Following adenosine-induced termination of atrio-ventricular reentrant tachycardia the patient developed polymorphic ventricular tachycardia followed by preexcited atrial fibrillation with very rapid ventricular response and syncope. Arrhythmia was terminated by amiodarone infusion. Potential complications after adenosine injection are discussed. |
9,030 | Radio-frequency ablation of arrhythmias following congenital heart surgery. | Cardiac arrhythmias as a late complication following congenital heart surgery are encountered more and more frequently in clinical practice. The use of new electrophysiological methods of visualisation and mapping improves the efficacy of radio-frequency (RF) ablation of these arrhythmias.</AbstractText>To assess patterns of atrial arrhythmias following congenital heart surgery and to examine the efficacy of RF ablation using the electro-anatomical CARTO system.</AbstractText>Electrophysiological diagnostic study and RF ablation were performed in 24 consecutive patients (mean age 36+/-18 years) who had atrial arrhythmias following congenital heart surgery. The mechanism of arrhythmia (ectopic or reentrant) and strategy of RF ablation procedure were based on the results of the right atrial map performed during index arrhythmia.</AbstractText>The patients were divided into five groups according to the type of congenital heart surgery. The ASD group consisted of 17 patients who had undergone in the past surgery due to atrial septal defect, four patients had a history of surgery due to ventricular septal defect (VSD group), and one patient each had undergone surgery due to corrected transposition of the great arteries (ccTGA), tetralogy of Fallot (TF) or dual-outflow right ventricle (DORV). During diagnostic electrophysiological study typical atrial flutter (AFL) was diagnosed in nine patients from the ASD group, atypical AFL in three ASD patients, and ectopic atrial tachycardia (EAT) in six ASD patients. In one patient EAT was induced after ablation of typical AFL. Of the VSD patients, three had atypical AFL, and one had typical AFL. The patient following surgery for ccTGA had atypical AFL and EAT, whereas in the two remaining patients (DORV and TF) atypical AFL was demonstrated. The efficacy of the first session of RF ablation was 83% and no complications were observed. The efficacy of RF ablation of typical AFL was 90%, atypical AFL 78%, and EAT 86% (NS). During the long-term follow-up (24+/-17 months) arrhythmia recurrences were noted in 2 (10%) out of 20 patients who were effectively treated during the first RF ablation session.</AbstractText>Reentry is the most common electrophysiological mechanism of incisional tachycardias, followed by ectopic atrial tachycardia. RF ablation using the electro-anatomical CARTO system is effective and safe in this group of patients.</AbstractText> |
9,031 | [Sudden cardiac arrest as the first symptom of coronary heart disease--case report]. | We describe the patient at whom sudden cardiac arrest was the first symptom of coronary heart disease. In the paper, we describe factors which influence the effectiveness of resuscitation in out of hospital cardiac arrest. Applying the cardiac massage by a bystander, the presence of defibrillation rhythm and short period of time to the first defibrillation, determined the survival of the patient. |
9,032 | [Positive microvolt T-wave alternans as a marker of ventricular arrhythmia trigering during cardioverter-defibrillator implantation]. | Microvolt T-wave alternans (MTWA) is promising method for noninvasive assessment of arrhythmic risk, but its role hasn't established yet. The aim of this study was to establish the MTWA potency to predict the ventricular arrhythmia triggering during implantable cordioverter-defibrillator (ICD) implantation. Material and metods. The study group consisted of 21 patients, aged 63.0+/-8.0 years; EF was 38.0+/-12.8%. Seventeen of them had a history of myocardial infarction and 4 had non-ischemic cardiomyopathy. The reason for ICD implantation were secondary prevention due to nonfatal cardiac arrest caused by VF/VT in nineteen patients and in two patients ICD was implanted because of unexplained syncope and low EF (< or =35%). All patients underwent VT/VF triggering during device implantation caused by electrophysiological study (EPS). If this proved ineffective aggressive protocol of 50 Hz BURST and T SHOCK was applied. After ICD implantation the following tests were performed: ECG with HR, QRS and QTc evaluation, 24-hour ECG Holter monitoring with HRV assessment and MTWA evaluation during treadmill exercise test. Results. In the group with VT/VF induced by less aggressive protocol (EPS), group I (n = 10) MTWA was present in nine patients, in one the result of MTWA was indeterminate. In the group with VT/VF induced by more aggressive protocol, group II (n = 11) MTWA was present in four patients, indeterminate in four and absent in three. There was a significant (p = 0.017) difference between group I and II in the frequency of positive result of MTWA. There were no differences between the two groups according to time domain parameters of HRV such as SDNN, RMSSD and PNN50 and QTc. There was a significant difference between the two groups in time duration of QRS complexes, 118.9+/-14.7 vs. 105.6+/-11.5 accordingly (p < 0.04). Conclusions. MTWA may help identify patients in whom VTNVF is more easily inducible by electrophysiologic study during ICD implantation. It is easier to induce ventricular arrhythmia when QRS complexes are wider, irrelevant to left ventricular dysfunction and autonomic function of the heart. |
9,033 | Prevention of life-threatening ventricular tachyarrhythmia by a novel and pure class-III agent, nifekalant hydrochloride. | Nifekalant hydrochloride (NIF) is a novel intravenous class-III antiarrhythmic agent with a pirimidinedione structure that purely blocks the K+ channel without inhibiting beta-adrenergic receptors. The authors investigated the efficacy of NIF for refractory ventricular tachycardia/fibrillation (VT/VF). They studied 30 patients treated with an intravenous infusion of NIF [ 26 men, 4 women; age: 63 +/- 17 (mean +/- SD) years] at a dose of 0.19 +/- 0.14 mg/kg body weight per hour. Sixteen were patients with acute coronary syndrome (ACS), and 14 were patients with chronic structural heart disease (Chr-HD). Amiodarone and sotalol had already been administered to 9 patients with Chr-HD before the administration of NIF. The QT and T peak-end (Tp-e) intervals were measured and corrected by Bazett's method (QTc, cTp-e). The left ventricular ejection fraction was depressed (28 +/- 9%). NIF was effective for preventing VT/VF without proarrhythmia and hemodynamic deterioration in 21 patients (70%; 12 with ACS; 9 with Chr-HD), but ineffective in 4 patients (all with Chr-HD). The QTc prolongation in the responders was more pronounced than in the nonresponders (25% +/- 15% versus 5% +/- 7% increase; P < 0.05). Proarrhythmic torsade de pointes (TdP) developed transiently in the remaining 5 patients in whom the cTp-e was markedly increased compared with that in the responders (93% +/- 49% versus 37% +/- 41% increase; P < 0.05). In conclusion, these findings indicate that the intravenous administration of NIF is useful in the emergent treatment of inhibiting drug-refractory VT/VF, although proarrhythmic TdP owing to an enhancement of transmural dispersion of repolarization needs to be taken into account. |
9,034 | Successful use of a transvenous dual-chamber automatic implantable cardiac defibrillator after a classic Fontan operation for tricuspid atresia. | We report the first successful totally percutaneous pacing and defibrillation of a single ventricle in a 52-year-old woman who had undergone a classic Fontan operation (atriopulmonary connection) for tricuspid atresia 21 years earlier. Left ventricular pacing and sensing was obtained with a bipolar lead in the lateral cardiac vein, and defibrillation was obtained with a coronary sinus coil lead and an "active can" in the retromammary position to optimize the current vector. This approach has significant potential benefits because it avoids a repeat thoracotomy, with its associated mortality and morbidity. |
9,035 | Multiple premature beats triggered ventricular arrhythmias during pilsicainide infusion in a patient with inferior ST-segment elevation. | A 17-year-old man was referred to our hospital for treatment of common paroxysmal atrial flutter. His electrocardiogram at rest showed subtle ST-segment elevation in leads II, III, and aV(F). Intravenous pilsicainide caused further ST-segment elevation in the inferior leads, new ST-segment depression in leads V2-V6, two distinct forms of premature ventricular complexes (PVCs) triggering short runs of polymorphic ventricular tachycardia (VT). An infusion of isoproterenol suppressed these arrhythmias and normalized the ST-segment. Pilsicainide may induce PVCs and polymorphic VT in atypical Brugada syndrome. |
9,036 | Differences in arrhythmogenicity between the canine right ventricular outflow tract and anteroinferior right ventricle in a model of Brugada syndrome. | The Brugada syndrome is characterized by ST-segment elevation on the ECG, especially in the right precordial leads sensitive to the right ventricular outflow tract (RVOT).</AbstractText>The purpose of this study was to evaluate the hypothesis that right ventricular electrophysiologic heterogeneity caused arrhythmogenicity in the Brugada syndrome.</AbstractText>Action potentials (APs) were mapped on the epicardium of 14 RVOT preparations and on the transmural surfaces of 15 pairs of RVOT and right ventricular anteroinferior (RVAI) preparations isolated from canine hearts. Brugada ECG and arrhythmias were induced with pilsicainide (2.5-12.5 micromol/L), pinacidil (1.25-12.5 micromol/L), and terfenadine (2.0 micromol/L).</AbstractText>Low doses of drugs elevated the J-ST segment and induced APs with both short and long action potential durations (APDs) in contiguous RVOT epicardial regions. In addition, APs in the RVOT had a larger phase 1 notch and longer APD than in RVAI. The longest APDs were in the epicardium in RVOT but in the endocardium in RVAI regions. High doses of drugs eliminated the phase 2 dome of the AP and abbreviated APDs in the epicardium but not in endocardium and reduced the epicardial heterogeneity of APs but increased the transmural gradient of APD in 14 (93%) of the RVOT preparations. In contrast, abbreviations of epicardial APDs occurred in only 4 (27%) of the RVAI preparations. Ventricular tachycardia occurred more frequently in the RVOT (47%) than in paired RVAI preparations (7%). Blocking the transient outward current reduced the heterogeneity of APs and eliminated arrhythmogenicity in all preparations.</AbstractText>Compared with the RVAI region, the RVOT has greater electrophysiologic heterogeneity that contributes to arrhythmogenicity in this model of Brugada syndrome.</AbstractText> |
9,037 | Interactive atrial neural network: Determining the connections between ganglionated plexi. | The electrophysiologic functions of the intrinsic cardiac autonomic nervous system (ANS) are not well understood.</AbstractText>The purpose of this study was to investigate the functional interactions between ganglionated plexi within the intrinsic cardiac ANS.</AbstractText>The hearts of 21 dogs were exposed via right and/or left thoracotomy to expose the (1) anterior right ganglionated plexi near the caudal end of the sinoatrial node, (2) inferior right ganglionated plexi at the junction of inferior vena cava and atria, and (3) superior left ganglionated plexi near the junction of left superior pulmonary vein and left pulmonary artery. Ganglionated plexi were stimulated at 0.6 to 8.0 V (square waves, 20 Hz, 0.1-ms duration). Sinus rate, AH interval during atrial pacing, and ventricular rate during atrial fibrillation were compared before and after ganglionated plexi stimulation and after their ablation.</AbstractText>Anterior right ganglionated plexi stimulation induced significant AH prolongation and slowing of ventricular rate and sinus rate. When inferior right ganglionated plexi was ablated, slowing of sinus rate by anterior right ganglionated plexi stimulation was unaltered, but inhibition of AV conduction was eliminated. Superior left ganglionated plexi stimulation induced similar effects on sinus and AV nodal function, and sinus rate slowing was markedly attenuated by anterior right ganglionated plexi ablation. Ablation of both anterior right ganglionated plexi and inferior right ganglionated plexi eliminated AV conduction inhibition but not sinus rate slowing by superior left ganglionated plexi stimulation.</AbstractText>This study provides functional evidence for the interconnections between ganglionated plexi to modulate sinus and AV nodal function, supporting clinical evidence that interconnections within the intrinsic cardiac ANS are critical elements in identifying the targets for atrial fibrillation ablation.</AbstractText> |
9,038 | Initial United States experience with the Paracor HeartNet myocardial constraint device for heart failure. | This study was undertaken to review the initial results and surgical safety data for the US Food and Drug Administration safety and feasibility trial of the Paracor HeartNet (Paracor Medical, Inc, Sunnyvale, Calif.) myocardial constraint device.</AbstractText>Patients with New York Heart Association functional class II or III heart failure underwent device implantation (n = 21) through a left minithoracotomy.</AbstractText>The average age was 53 years (31-72 years). There were 18 men and 3 women, and 17 patients had nonischemic etiology of heart failure. Mean heart failure duration was 8.3 years (1.4-18.8 years). Average ejection fraction was 22% (11%-33%), with an average left ventricular end-diastolic dimension of 74 mm (55-94 mm). Previous medical therapy included angiotensin-converting enzyme inhibitors, beta-blockers, diuretics, digoxin, and aldosterone receptor blockers. At implantation, 17 patients had implantable electronic devices: 1 biventricular pacemaker, 11 biventricular pacemakers with cardioverter-defibrillators, and 5 implantable cardioverter-defibrillators. Patient comorbidities included hypertension in 10 cases, diabetes mellitus in 8, myocardial infarction in 1, and ventricular tachycardia in 8. Mean operative time was 68 minutes (42-102 minutes), and implantation time averaged 15 minutes (5-51 minutes). The average time to ambulation was 1.6 days (1-4 days). The intensive care unit stay averaged 3.3 days (1-16 days), and hospital stay averaged 6.3 days (4-16 days). Atrial fibrillation occurred in 2 patients, and there were 2 in-hospital deaths.</AbstractText>The Paracor device can be implanted in patients with heart failure and reduced left ventricular function with a high degree of success. Significant surgical complications were infrequent. The initial US experience supports the conduct of a randomized, controlled, pivotal trial.</AbstractText> |
9,039 | Impact of left atrial appendage exclusion on left atrial function. | We sought to investigate the short-term and midterm effects of left atrial appendage exclusion on left atrial function. Left atrial appendage exclusion is considered a possible therapeutic option for stroke prevention in patients with atrial fibrillation. Favorable outcomes have encouraged widespread use of left atrial appendage exclusion for cardiac surgical patients-even for patients in sinus rhythm who have stroke risk factors; however, the chronic effects on left atrial function of left atrial appendage exclusion are unclear.</AbstractText>Nineteen mongrel dogs (29.7 +/- 5.2 kg) in sinus rhythm were studied. The Doppler signals from the pulmonary venous flow, transmitral flow, and tissue Doppler imaging of mitral annular motion were obtained before and after left atrial appendage exclusion. Dogs were evaluated in the same manner at 7 days (n = 2), 30 days (n = 7), or 90 days (n = 10) after left atrial appendage exclusion.</AbstractText>Except for a significant increase in early diastolic transmitral flow velocity after left atrial appendage exclusion (P = .01), no significant differences were found in any parameters related to the transmitral flow and tissue Doppler imaging measurements throughout follow-up. The systolic components of pulmonary venous flow at follow-up revealed a significant reduction relative to baseline (peak systolic velocity P < .0001, systolic velocity-time integral P < .0001), despite the lack of significant changes in left atrial pressure, left ventricular volume, and stroke volume.</AbstractText>Left atrial appendage exclusion may affect left atrial reservoir function in the short-term and midterm periods. Further long-term studies with more clinically relevant models are needed.</AbstractText> |
9,040 | Melatonin reduces ventricular arrhythmias and preserves capillary perfusion during ischemia-reperfusion events in cardiomyopathic hamsters. | Earlier studies showed that melatonin has powerful antioxidative effects on ischemia-reperfusion (I/R) injury in healthy hamsters. In the present study, the possible protective effects of melatonin in 10-month-old cardiomyopathic (CM) hamsters were evaluated in a model of I/R in the cheek pouches observed by intravital microscopy. In CM (BIO 14.6) hamsters diameter, red blood cell (RBC) velocity and flow in arterioles as well as lipid peroxide and nitrite/nitrate concentrations in the systemic blood, perfused capillary length, vascular permeability, and leukocyte adhesion were measured after melatonin injection (6 mg/kg intraperitoneally daily for 3 weeks), and after I/R. The influence of melatonin on the incidence of postischemic-reperfusion-induced ventricular tachycardia (VT) and ventricular fibrillation (VF) were also measured. Changes in the arteriolar response to NG-monomethyl-L-arginine (L-NMMA), a nitric oxide inhibitor, norepinephrine (NE), and angiotensin II (ANG II) were studied before and after melatonin injection (10 mg/kg intravenously). In CM hamsters, melatonin restored normal arteriolar responses to L-NMMA, NE, and ANG II. I/R elevated lipid peroxide and nitrate/nitrite levels, and vascular permeability while arteriolar diameter, RBC velocity, flow and capillary perfusion were reduced. These effects were more marked in CM versus healthy hamsters. During I/R melatonin reduced oxidative and nitrosative stress, vasoconstriction, leukocyte adhesion, and vascular permeability and increased capillary perfusion. Melatonin reduced the incidence of VT while VF during reperfusion disappeared totally. In conclusion, melatonin prevents both microvascular injury and ventricular arrhythmias during postischemic reperfusion by modulating the lipid peroxide overproduction and nitrative stress which are involved in the development of cardiomyopathy. |
9,041 | Milrinone combined with vasopressin improves cardiac index after cardiopulmonary resuscitation in a pig model of myocardial infarction. | Milrinone used for acute cardiac insufficiency could be of interest during cardiopulmonary resuscitation because of its positive inotropic effects. In this study, the combination of milrinone-vasopressin was compared with epinephrine and vasopressin, as well as with the combination of epinephrine-vasopressin, in reference to hemodynamics.</AbstractText>Thirty-two pigs underwent ligation of the circumflex coronary artery and induction of ventricular fibrillation lasting for 4 min. Cardiopulmonary resuscitation was performed after randomization to one of four groups: epinephrine (30-microg/kg bolus), vasopressin (0.4-U/kg bolus), epinephrine-vasopressin (15-microg/kg epinephrine bolus, 0.2-U/kg vasopressin bolus), or milrinone-vasopressin (0.4-U/kg vasopressin bolus, 50-microg/kg milrinone bolus over 5 min and a continuous infusion of 0.4 microg.kg.min). The hemodynamic variables were measured before cardiopulmonary resuscitation as well as 4, 8, 15, and 30 min after return of spontaneous circulation.</AbstractText>All animals were resuscitated successfully. The animals of the milrinone-vasopressin group displayed significantly (P<0.05) higher cardiac index values (30 min after return of spontaneous circulation: epinephrine, 65.8+/-13.2; vasopressin, 70.7+/-18.3; epinephrine-vasopressin, 69.1+/-36.2; milrinone-vasopressin, 120.7+/-34.8 ml.min.kg) without a decrease in mean arterial pressure or coronary perfusion pressure.</AbstractText>The combination of vasopressin-milrinone as compared with epinephrine during cardiopulmonary resuscitation leads to an improved cardiac index without relevant decrease of mean arterial pressure or coronary perfusion pressure.</AbstractText> |
9,042 | Crosstalk between L-type calcium channels and ZnT-1, a new player in rate-dependent cardiac electrical remodeling. | Crosstalk between two membrane transport systems is an established mechanism underlying regulation. In this study, we investigated the interaction between ZnT-1, a putative plasma membrane zinc transporter, and L-type voltage-dependent calcium channels (LTCC). In the atrium of the myocardium decreased activity of the LTCC is a dominant feature of patients with atrial fibrillation. The trigger for this inhibition has been attributed to the rapid firing rates and consequent calcium overload in the atrial cardiomyocytes. However, the underlying mechanism of LTCC inhibition is still to be elucidated. Here, we showed that the expression of ZnT-1 inhibits the activity of L-type channels during electrical remodeling induced by rapid pacing. (i) Direct manipulations of ZnT-1 expression in cultured cardiomyocytes either by ZnT-1 overexpression or by ZnT-1 silencing with siRNA, decreased or enhanced, respectively, the barium influx through the LTCC. (ii) Co-expression of ZnT-1 with LTCC in Xenopus oocytes decreased whole cell barium current through LTCC. (iii) Rapid pacing of cultured cardiomyocytes (4 h, 100 ms cycle) increased ZnT-1 protein expression and inhibited the voltage-dependent divalent cation influx through the LTCC. Moreover, silencing ZnT-1 with siRNA prevented the rapid pacing induced inhibition of the LTCC (iv) Atrial pacing of anesthetized adult rats (4 h, 50 ms cycle) led to a significant increase in atrial ZnT-1 protein expression in parallel with the typical decrease of the refractory period in the atria. Taken together, these findings demonstrate that crosstalk between ZnT-1 and the L-type calcium channels may underlie atrial response to rapid pacing, suggesting that ZnT-1 is a significant participant in rate-dependent cardiac electrical remodeling. |
9,043 | Diagnostic and prognostic value of a type 1 Brugada electrocardiogram at higher (third or second) V1 to V2 recording in men with Brugada syndrome. | To evaluate the diagnostic and prognostic value of an electrocardiogram (ECG) recorded at a higher (third or second) intercostal space, 98 men (17 to 76 years of age, mean +/- SD 47 +/- 13; with documented ventricular fibrillation [VF] in 22 and syncope in 32) were categorized into 3 groups; 68 men had a spontaneous type 1 ECG in standard leads V(1) and V(2) (S group), 19 had a spontaneous type 1 ECG only in the higher V(1) and V(2) leads (H group), and 11 had a type 1 ECG only after receiving class Ic sodium channel blockers (Ic group). There were no significant differences in baseline clinical characteristics, including VF episodes, syncope, atrial fibrillation, family history, late potentials, and inducibility of VF during electrophysiologic study across the 3 groups. During prospective follow-up periods (779 +/- 525, 442 +/- 282, and 573 +/- 382 days, respectively), subsequent cardiac events occurred in 11 men (16%) within the S group, in 2 men (11%) in the H group, and in 0 men (0%) in the Ic group (p = NS, S vs H group). In men with previous episodes of VF, subsequent cardiac events occurred in 7 (44%) within the S group and in 2 (50%) in the H group (p = NS). In conclusion, men with a spontaneous type 1 Brugada ECG recorded only at higher leads V(1) and V(2) showed a prognosis similar to that of men with a type 1 ECG in using standard leads V(1) and V(2). |
9,044 | [Cardiac arrhythmias in the elderly]. | In the elderly, cardiac arrhythmias and conduction disturbances are characterized by their high frequency, diagnostic difficulties, low tolerance, and delicate treatment. Atrial fibrillation, the prevalence of which exceeds 10% after 80 years, is usually related to hypertensive or ischemic heart disease, and is the cause or the consequence of heart failure. It is first and foremost a cause of thromboembolic events, and especially cerebrovascular embolism. In elderly patients, sinus node dysfunction and AV block are often induced or aggravated by drugs. The iatrogenic risk associated with antiarrhythmic drugs (especially class I) and antithrombotic drugs is elevated in the elderly, and these agents must thus be used with great care. Ventricular rate control is often a safer option than sinus rhythm control for atrial fibrillation. Ablative methods and cardiac pacing techniques are other therapeutic options. |
9,045 | [Biology of cardiac and vascular senescence]. | None of the many theories of senescence can account for the aging process in its entirety. These theories include the evolutionary theory of aging and its EvoDevo corollary, the replicative senescence and free radicals theory, theories based on large-scale analyses (proteomics, etc.), and systemic theories. Cardiovascular senescence is first and foremost due to vascular senescence. Aging is associated with enhanced aortic characteristic impedance, which is mainly due to glycation of vessel wall proteins. This increased impedance overloads the left ventricle and causes compensatory left ventricular hypertrophy, usually associated with fibrosis. Extreme aging (> 80 years in humans, > 30 months in rats) is associated with age-related heart failure. Senescence favors heart failure, atrial fibrillation and cardiac hypertrophy. It is also associated with increased systolic pressure and decreased diastolic pressure. The most characteristic features are enhanced pulse pressure and arterial compliance. |
9,046 | [Arrhythmia-induced dilated cardiomyopathies]. | Arrhythmic cardiomyopathies are due to ventricular dysfunction following prolonged or chronic tachycardia; the clinical pictures one of congestive heart failure, which is totally reversible after the treatment of tachycardia and the restoration of sinus rhythm. Since Whipple's first description of this model of heart failure, several teams have shown that ventricular or atrial pacing at rates exceeding 220 beats per minute produces a profound and largely reversible depression of ventricular function, and a constellation of neuroendocrine abnormalities and metabolic, electrophysiological and anatomic alterations of the myocardium. The associated heart failure generally starts to improve within days of achieving ventricular rhythm control, but clinical recovery may take several weeks or months. All forms of chronic tachycardia may induce heart failure, but the onset of cardiomyopathy depends more on the heart rate and the duration of the arrhythmia than on its type. The pathophysiological mechanisms are multiple and complex, and include abnormalities in the structure and function of cardiomyocytes and disturbances in excitation-contraction coupling. Treatment consists of restoring and maintaining sinus rhythm, or at least of controlling the ventricular rate. Because of its curative effect, selective radiofrequency ablation is the treatment of choice when the arrhythmogenic substrate is localized. Control of the ventricular rate by radiofrequency modification of atrioventricular conduction is the treatment of choice for chronic atrial fibrillation. |
9,047 | [Automated external defibrillation in children]. | Ventricular fibrillation is an infrequent arrhythmia in cardiac arrest occurring in the out-of-hospital setting in infants and small children. However, outcome is good provided early defibrillation is performed; consequently, this procedure is one of the main links in the chain of survival in children with a shockable rhythm. Automated external defibrillators are small devices that can analyze heart rhythm and deliver a dose of electric energy when considered timely by the operator. Automated external defibrillators are easy to use and can be operated, if necessary, by anyone. Therefore, all pediatricians should be aware of how these devices work and be able to use them safely and effectively, following the current defibrillation protocol. |
9,048 | Heart rate turbulence and variability in patients with ventricular arrhythmias. | To evaluate the changes in autonomic neural control mechanisms before malignant ventricular arrhythmias, we measured heart rate variability (HRV) and heart rate turbulence (HRT) in patients with ventricular tachycardia or fibrillation (Group I; n=6), non sustained ventricular tachycardia (Group II; n=32), frequent premature ventricular beats (Group III; n=26) and with ICD implantation (Group IV; n=11).</AbstractText>Time domain parameters of HRV and turbulence onset (TO) and slope (TS) were calculated on 24 hour Holter recordings. Normal values were: SDNN > 70 msec for HRV, TO <0% and TS >2.5 msec/RR-I for HRT.</AbstractText>Whereas SDNN was within normal range and similar in all study groups, HRT parameters were significantly different in patients who experienced VT/VF during Holter recording. Abnormal TO and/or TS were present in 100% of Group I patients and only in about 50% of Group II and IV. On the contrary, normal HRT parameters were present in 40-70% of Group II, III and IV patients and none of Group I.</AbstractText>These data suggest that HRT analysis is more suitable than HRV to detect those transient alterations in autonomic control mechanisms that are likely to play a major trigger role in the genesis of malignant cardiac arrhythmias.</AbstractText> |
9,049 | Tachycardia-induced Cardiomyopathy (Tachycardiomyopathy). | The term tachycardia-induced cardio-myopathy or tachycardiomyopathy refers to impairment in left ventricular function secondary to chronic tachycardia, which is partially or completely reversible once the tachyarrhythmia is controlled. Tachycardia-induced cardiomyopathy has been shown to occur both in experimental models and in patients with incessant tachyarrhythmia. Data from several studies and from case reports have shown that rate control by means of cardioversion, negative chronotropic agents, and surgical or catheter-based atrio-ventricular node ablation, resulted in significant improvement of systolic function. The diagnosis of tachycardia-induced cardiomyopathy is usually made following observation of marked improvement in systolic function after normalization of heart rate. Clinicians should be aware that patients with unexplained systolic dysfunction may have tachycardia-induced cardiomyo-pathy, and that controlling the arrhythmia may result in improvement of systolic function. |
9,050 | [The concise history of atrial fibrillation]. | The author reviews the history of atrial fibrillation, the most common sustained cardiac arrhythmia. The chaotic irregularity of arterial pulse was clearly acknowledged by most of physicians of the ancient China, Egypt and Greece. William Harvey (1578-1657), who first described the circulatory system appropriately, was probably the first to describe fibrillation of the auricles in animals in 1628. The French "clinical pathologist", Jean Baptist de Sénac (1693-1770) was the first who assumed a correlation between "rebellious palpitation" and stenosis of the mitral valve. Robert Adams (1791-1875) also reported in 1827 the association of irregular pulses and mitral stenosis. The discovery of digitalis leaf in 1785 by William Withering (1741-1799) brought relief to patients with atrial fibrillation and congestive heart failure by reducing the ventricular rate. From an analysis of simultaneously recorded arterial and venous pressure curves, the Scottish Sir James Mackenzie (1853-11925) demonstrated that a presystolic wave cannot be seen during "pulsus irregularis perpetuus", a term very first used by Heinrich Ewald Hering (1866-1948). Arthur Cushny (1866-1926) noted the similarity between pulse curves in clinical "delirium cordis" and those in dogs with atrial fibrillation. The first human ECG depicting atrial fibrillation was published by Willem Einthoven (1860-1927) in 1906. The proof of a direct connection between absolute arrhythmia and atrial fibrillation was established by two Viennese physicians, Carl Julius Rothberger and Heinrich Winterberg in 1909. Sir Thomas Lewis (1881-1945), the father of modem electrocardiography, studied electrophysiological characteristics of atrial fibrillation and has shown that its basic perpetuating mechanism is circus movement of electrical impulse (re-entry). After him, the major discoveries relating to the pathophysiology and clinical features of atrial fibrillation in the 20th century stemmed from Karel Frederick Wenckebach (1864-1940), Gordon Moe (1915-1989), Bernhard Lown (*1921) and Maurits Allessie. Over the past ten years, awareness has increased of transcatheter radiofrequency and cryoablation of non-valvular atrial fibrillation and the battle against formation of intraatrial thrombi for preventing cerebral thromboembolism. |
9,051 | Diagnostic and genetic aspects of the Brugada and other inherited arrhythmias syndromes. | Doctor Wilde, presenting on behalf of himself and Dr Eckardt, discussed the role of invasive and noninvasive tests for risk stratification of Brugada syndrome. Doctor Hiraoka, presenting on behalf of Y. Yokoyama, M. Takagi, N. Aihara, K. Aonuma, and the Japan Idiopathic Ventricular Fibrillation Study Investigators, further discussed the diagnostic criteria for the Brugada syndrome. Doctor Antzelevitch examined the hypothesis that amplification of spatial dispersion of repolarization in the form of transmural dispersion of repolarization underlies the development of life-threatening ventricular arrhythmias associated with inherited ion channelopathies including the long QT, short QT, and Brugada syndromes. Doctor Corrado discussed the relationship between channelopathies and heart muscle diseases. |
9,052 | [Atrioventricular block in unstable angina. Results of the ARIAM registry]. | Describe the frequency of high degree atrioventricular block (HDAVB) in patients with unstable angina (UA), analyze the variables associated with their appearance and evaluate whether HDAVB is independently associated with increased mortality or increased length of ICU stay.</AbstractText>Retrospective descriptive study of patients with UA included in the ARIAM registry.</AbstractText>ICUs from 129 hospitals in Spain.</AbstractText>From June 1996 to December 2003 a total of 14,096 patients were included in the ARIAM registry with a diagnosis of UA.</AbstractText>Variables associated with the development of HDAVB, variables associated with the mortality of patients with UA, variables associated with the length of ICU stay of patients with UA.</AbstractText>HDAVB frequency was 1%. Development of HDAVB was independently associated with the Killip classification and the presence of sustained ventricular tachycardia or ventricular fibrillation. Crude mortality of patients was significantly increased when HDAVB was present (9% versus 1%, p < 0,001). When adjusted for other variables, HDAVB was not associated with increased mortality. Development of HDAVB in patients with UA was independently associated with an increase in the length of ICU stay (adjusted odds ratio 1.89: 95% confidence interval: 1.33-5.69).</AbstractText>Patients with UA complicated with HDAVB represent a high-risk population with an increased ICU stay.</AbstractText> |
9,053 | Clinical trials update from the American Heart Association 2006: OAT, SALT 1 and 2, MAGIC, ABCD, PABA-CHF, IMPROVE-CHF, and percutaneous mitral annuloplasty. | This article provides information and a commentary on trials presented at the American Heart Association meeting held in November 2006, relevant to the pathophysiology, prevention and treatment of heart failure. All reports should be considered as preliminary data, as analyses may change in the final publication. The OAT study failed to show a benefit of PCI over optimal medical therapy in patients with persistent total occlusion of the infarct related artery following a myocardial infarction. In SALT 1 and 2, tolvaptan was found to correct hyponatraemia of various aetiologies; however, whether this has an impact on heart failure prognosis requires further evaluation. A placebo controlled study of myocardial implantation of skeletal myoblasts in patients with moderate to severe LVSD (MAGIC) showed equivocal/uncertain effects, long term follow-up data are awaited. The ABCD study which compared the ability of an invasive and a non-invasive test to identify patients at risk of arrhythmic events prior to ICD implantation, suggested that the two strategies were comparable, although the practical value of either test remains uncertain and the study had many major flaws. The PABA-CHF study hinted that pulmonary vein antrum isolation might be more effective than AV node ablation with bi-ventricular pacing for the treatment of patients with heart failure in atrial fibrillation. In IMPROVE-CHF, an NT-pro BNP guided treatment strategy was found to reduce the cost of managing patients with acute breathlessness. |
9,054 | Characteristic features of QRST integral mapping in patients with high risk Brugada syndrome. | The characteristic features of QRST integral mapping in the Brugada-type resting ECG of patients at a high risk for life-threatening ventricular arrhythmias were examined.</AbstractText>QRST integral mapping was performed in 11 Brugada-type ECG patients with histories of aborted sudden death, spontaneous ventricular tachycardia and fibrillation (VT/VF) or programmed electric stimulation-inducible VT/VF (high risk group); 13 Brugada-type ECG patients without a history of such events (low risk group); and 21 age-matched healthy controls. Individual QRST isointegral maps revealed the minimum integral in the mid-to-right upper chest in 100% and 85% of the control and low risk groups, respectively, whereas this integral was 64% in the upper right back of the high risk group (p<0.05). On the QRST integral departure maps, the abnormal positive departure area (integral value>or=+2 standard deviation) was located in the mid-to-right upper chest in 82% and 8% of the high and low risk groups, respectively (p<0.05). During the follow-up period, sudden death or VF occurred in 4 of 6 high risk patients with both the abnormal findings.</AbstractText>The abnormal positive departure area in the mid-to-right upper chest and the minimum QRST integral in the right upper back were distinct hallmarks for screening patients with the high risk Brugada-type ECG.</AbstractText> |
9,055 | Bi-ventricular circulatory support with the Abiomed AB5000 system in a patient with idiopathic refractory ventricular fibrillation. | A 45-year-old man had life-threatening recurrent idiopathic ventricular fibrillation and persistent cardiogenic shock develop. The episodes of ventricular fibrillation were refractory to aggressive medical management; therefore an Abiomed AB5000 bi-ventricular support system was implanted for arrhythmia control. The device was able to maintain hemodynamic stability during the following 2 weeks. The patient was discharged from the hospital with fully recovered cardiac function. |
9,056 | Coronary arterial fistulas. | A coronary arterial fistula is a connection between one or more of the coronary arteries and a cardiac chamber or great vessel. This is a rare defect and usually occurs in isolation. Its exact incidence is unknown. The majority of these fistulas are congenital in origin although they may occasionally be detected after cardiac surgery. They do not usually cause symptoms or complications in the first two decades, especially when small. After this age, the frequency of both symptoms and complications increases. Complications include 'steal' from the adjacent myocardium, thrombosis and embolism, cardiac failure, atrial fibrillation, rupture, endocarditis/endarteritis and arrhythmias. Thrombosis within the fistula is rare but may cause acute myocardial infarction, paroxysmal atrial fibrillation and ventricular arrhythmias. Spontaneous rupture of the aneurysmal fistula causing haemopericardium has also been reported. The main differential diagnosis is patent arterial duct, although other congenital arteriovenous shunts need to be excluded. Whilst two-dimensional echocardiography helps to differentiate between the different shunts, coronary angiography is the main diagnostic tool for the delineation of the anatomy. Surgery was the traditional method of treatment but nowadays catheter closure is recommended using a variety of closure devices, such as coils, or other devices. With the catheter technique, the results are excellent with infrequent complications. |
9,057 | Successful resuscitation of an ASA 3 patient following ropivacaine-induced cardiac arrest. | A patient with severe myocardial disease and acute-on-chronic renal failure was undergoing a brachial plexus block for formation of an arteriovenous fistula when accidental intravascular injection of ropivacaine resulted in ventricular fibrillation. Cardiopulmonary resuscitation was instituted immediately and the advanced life support algorithm was followed until the return of sinus rhythm. Although, in comparison with bupivacaine, ropivacaine appears to be a safer local anaesthetic agent in the setting of intravenous injection, the emphasis on safety should remain a priority. Awareness of the risk of central nervous system and cardiovascular toxicity and preparation for immediate commencement of resuscitation in the event of toxicity remain of paramount importance. |
9,058 | Therapeutic hypothermia after out-of-hospital cardiac arrest: experiences with patients treated with percutaneous coronary intervention and cardiogenic shock. | Therapeutic hypothermia has been shown to increase survival after out-of-hospital cardiac arrest (OHCA). The trials documenting such benefit excluded patients with cardiogenic shock and only a few patients were treated with percutaneous coronary intervention prior to admission to an intensive care unit (ICU). We use therapeutic hypothermia whenever cardiac arrest patients do not wake up immediately after return of spontaneous circulation.</AbstractText>This paper reports the outcome of 50 OHCA patients with ventricular fibrillation admitted to a tertiary referral hospital for immediate coronary angiography and percutaneous coronary intervention when indicated. Patients were treated with intra-aortic balloon counterpulsation (IABP) (23 of 50 patients) if indicated. All patients who were still comatose were treated with therapeutic hypothermia at 32-34 degrees C for 24 h before rewarming. The end-points were survival and cerebral performance category (CPC: 1, best; 5, dead) after 6 months.</AbstractText>Forty-one patients (82%) survived until 6 months. Thirty-four patients (68%) were in CPC 1 or 2, and seven (14%) were in CPC 3. Of the 23 patients treated with IABP, 14 (61%) survived with CPC 1 or 2. In patients not treated with IABP, 20 patients (74%) survived with CPC 1 or 2. Forty patients (80%) developed myocardial infarction. Percutaneous coronary intervention was performed in 36 patients (72%).</AbstractText>In OHCA survivors who reached our hospital, the survival rate was high and the neurological outcome acceptable. Our results indicate that the use of therapeutic hypothermia is justified even in haemodynamically unstable patients and those treated with percutaneous coronary intervention.</AbstractText> |
9,059 | [Implanted cardioverters-defibrillators in the treatment of arrhythmias and prevention of sudden death]. | To present 15-year experience in use of implantable cardioverters-defibrillators (ICD) in patients with life threatening arrhythmias and a high risk of sudden cardiac death (SCD).</AbstractText>A total of 151 patients (116 males and 35 females aged 12-75 years) with life threatening arrhythmias and ICD were studied.</AbstractText>There were neither complications nor lethality. Electrocardiotherapy was performed in 89 (58.9%) patients 4.5 +/- 9.4 months, on the average, after ICD implantation. Attacks of ventricular tachycardia (VT) were arrested by antitachycardia stimulation (974 episodes, 37.5 +/- 92.5 per patient, on the average). Effective cardioversion in VT was observed in 63 (41.7%) cases. Episodes of rapid ventricular tachycardia and ventricular fibrillation were stopped by defibrillation shocks in 28 (18.5%) patients. Additional surgical interventions were made in 3 patients because of electrodes dislocation, in 1--because of electrode brakage and in 1--suppuration of the bed. Fifteen patients (9%) died during follow-up because of cardiac failure (n = 13), cancer (n = 1), unknown cause (n = 1).</AbstractText>Clinical application of ICD is not only treatment of arrhythmia and prevention of SCD but it is also a method of diagnosis, collection and accumulation of information about the disease course.</AbstractText> |
9,060 | Importance of the autonomic nervous system in an experimental model of commotio cordis. | Young athletes may die suddenly when they are struck in the chest (commotio cordis). Proposed mechanisms of sudden death in commotio cordis include hypervagatonia and activation of the sympathetic nervous system. In an experimental model of commotio cordis, the importance of the sympathetic and parasympathetic nervous system in the initiation of ventricular fibrillation was evaluated.</AbstractText><AbstractText Label="MATERIAL/METHODS" NlmCategory="METHODS">Juvenile swine weighing between 8 and 12 kg were anesthetized with ketamine and isoflurane and placed prone in a sling. Twenty animals were randomized to pretreatment with placebo or sympathetic and parasympathetic blockade. Chest blows were guided by echocardiography to the center of the left ventricle and animals received 1-3 strikes with a regulation baseball propelled at 30 mph and timed to impact 10-30 ms prior to the peak of the T-wave.</AbstractText>With 17 impacts in 10 autonomically blocked animals, 6 episodes of ventricular fibrillation were seen; with 15 impacts in 10 control animals, ventricular fibrillation occurred 6 times. There was also no significant difference between the groups in occurrence of nonsustained polymorphic ventricular tachycardia or ST elevation. Transient complete heart block was less commonly seen in animals treated with autonomic blockade, although this did not achieve statistical significance.</AbstractText>In this experimental model of commotio cordis, autonomic blockade did not affect the frequency of sudden cardiac death, polymorphic ventricular tachycardia or ST segment elevation. Thus, vagotonic and sympathetic surges likely do not contribute to the syndrome of sudden death due to chest blows in young people and athletes.</AbstractText> |
9,061 | Unrecognized anomalous origin of the left coronary artery from the pulmonary artery as a cause of ventricular fibrillation after patent ductus arteriosus ligation in an infant. | We present a case of an infant who developed ventricular fibrillation after patent ductus arteriosus (PDA) ligation. The infant had unrecognized anomalous origin of the left coronary artery from the pulmonary artery before PDA ligation. Acute reduction in systemic pulmonary artery pressures after PDA ligation resulted in an abrupt reduction in left main coronary artery blood flow. After prompt resuscitation, cardiac catheterization confirmed the diagnosis of anomalous origin of the left coronary artery from the pulmonary artery. The infant subsequently underwent coronary artery translocation and recovered uneventfully. |
9,062 | Perioperative beta-blockers for preventing surgery-related mortality and morbidity: a systematic review and meta-analysis. | Perioperative beta-blockers are suggested to reduce cardiovascular mortality, myocardial-ischemia/infarction, and supraventricular arrhythmias after surgery. We reviewed the evidence regarding the effectiveness of perioperative beta-blockers for improving patient outcomes after cardiac and noncardiac surgery.</AbstractText>Eleven large databases were searched from the time of their inception until October 2005. Various online-resources were consulted for the identification of unpublished trials and conference abstracts. We included randomized, controlled trials comparing perioperative beta-blockers with either placebo or the standard-of-care. Of the 3680 retrieved titles, 69 met inclusion criteria for analysis. Odds ratios (OR) assuming random effects were computed in the absence of significant clinical heterogeneity.</AbstractText>Beta-blockers reduced the frequency of ventricular tachyarrhythmias [OR (cardiac surgery): 0.28, 95% CI 0.13-0.57; OR (noncardiac surgery): 0.56, 95% CI 0.21-1.45], atrial fibrillation/flutter [OR (cardiac surgery): 0.37, 95% CI 0.28-0.48], other supraventricular arrhythmias [OR (cardiac surgery): 0.25, 95% CI 0.18-0.35; OR (noncardiac surgery): 0.43, 95% CI 0.14-1.37], and myocardial ischemia [OR (cardiac surgery): 0.49, 95% CI 0.17-1.4; OR (noncardiac surgery): 0.38, 95% CI 0.21-0.69]. Length of hospitalization was not reduced [weighted mean difference (cardiac surgery): -0.35 days, 95% CI -0.77-0.07; weighted mean difference (noncardiac surgery): -5.59 days, 95% CI -12.22-1.04] and, in contrast to previous reports, beta-blockers did not reduce mortality [OR (cardiac surgery): 0.55, 95% CI 0.17-1.83; OR (noncardiac surgery): 0.78, 95% CI 0.33-1.87], and they had no influence on the occurrence of perioperative myocardial infarction [OR (cardiac surgery): 0.89, 95% CI 0.53-1.5; OR (noncardiac surgery): 0.59; 0.25-1.39].</AbstractText>Beta-blockers reduced perioperative arrhythmias and myocardial ischemia, but they had no effect on myocardial infarction, mortality, or length of hospitalization.</AbstractText> |
9,063 | Left atrial size and risk of major cardiovascular events during antihypertensive treatment: losartan intervention for endpoint reduction in hypertension trial. | The influence of left atrial size on cardiovascular events during antihypertensive treatment has not been reported previously from a long-term, prospective, randomized hypertension treatment trial. We recorded left atrial diameter by annual echocardiography and cardiovascular events in 881 hypertensive patients (41% women) with electrocardiographic left ventricular hypertrophy aged 55 to 80 (mean: 66) years during a mean of 4.8 years of randomized losartan- or atenolol-based treatment in the Losartan Intervention for Endpoint Reduction in Hypertension Study. During follow-up, a total of 88 primary end points (combined cardiovascular death, myocardial infarction, or stroke) occurred. In Cox regression, baseline left atrial diameter/height predicted incidence of cardiovascular events (hazard ratio: 1.98 per cm/m [95% CI: 1.02 to 3.83 per cm/m]; P=0.042) adjusted for significant effects of Framingham risk score and history of atrial fibrillation. Greater left atrial diameter reduction during follow-up was associated with greater reduction in left ventricular hypertrophy, absence of new-onset atrial fibrillation or mitral regurgitation during follow-up, and losartan-based treatment (B=-0.13+/-0.03 cm/m; P<0.001) in multiple linear regression, adjusting for baseline left atrial diameter/height. However, in time-varying Cox regression analysis, left atrial diameter reduction was not independent of left ventricular hypertrophy regression in predicting cardiovascular events during follow-up. In conclusion, left atrial diameter/height predicts risk of cardiovascular events independent of other clinical risk factors in hypertensive patients with left ventricular hypertrophy and may be useful in pretreatment clinical assessment of cardiovascular risk in these patients. |
9,064 | Incidence and clinical relevance of supraventricular tachyarrhythmias in pulmonary hypertension. | In patients with severe pulmonary hypertension (PH), right ventricular function is a main determinant of clinical stability and outcome. Supraventricular tachyarrhythmias (SVTs) may compromise cardiac function and threaten prognosis in patients with PH, but the incidence and clinical relevance of SVTs in PH and chronic right ventricular failure have not been evaluated.</AbstractText>In a 6-year retrospective single-center analysis, 231 consecutive patients followed for pulmonary arterial hypertension, or inoperable chronic thromboembolic PH were studied for SVTs. Analysis included incidence, clinical consequences, treatment, and outcome.</AbstractText>Thirty-one episodes of SVT were observed in 27 of 231 patients (cumulative incidence 11.7%, annual risk 2.8% per patient), including atrial flutter (n = 15), atrial fibrillation (n = 13), and AV nodal reentry tachycardia (n = 3). Supraventricular tachyarrhythmia onset was almost invariably associated with marked clinical deterioration and right ventricular failure (84% of SVT episodes). Outcome was strongly associated with the type of SVT and restoration of sinus rhythm. During follow-up, cumulative mortality was low (6.3%, follow-up 26 +/- 23 months) when sinus rhythm was restored (all cases of AV nodal reentry tachycardia and atrial flutter). In contrast, 9 of 11 patients with sustained atrial fibrillation died from right ventricular failure (cumulative mortality 82%, follow-up 11 +/- 8 months).</AbstractText>In patients with PH, SVTs constitute a relevant problem, often resulting in clinical deterioration. Sustained atrial fibrillation may be associated with a high risk of death from right ventricular failure.</AbstractText> |
9,065 | Persistent atrial fibrillation is associated with appropriate shocks and heart failure in patients with left ventricular dysfunction treated with an implantable cardioverter defibrillator. | The objective of this study was to investigate whether persistent atrial fibrillation (AF) and new-onset AF are associated with appropriate shocks, cardiovascular mortality, chronic heart failure (CHF), and inappropriate shocks in implantable cardioverter defibrillator (ICD) patients with left ventricular dysfunction.</AbstractText>We included 290 consecutive ICD patients with a documented left ventricular ejection fraction < or = 0.35 and compared outcomes between patients without AF (n = 207), those with persistent AF (n = 64), and those with new-onset AF (n = 19).</AbstractText>The patients with persistent AF were older, more frequently had valve disease and cardiac surgery, and less frequently had coronary artery disease as compared with the patients without AF. Patients with persistent AF had a higher New York Heart Association class, however, left ventricular ejection fraction rates between these 2 groups were comparable (0.28 +/- 0.07 vs 0.29 +/- 0.08, P = not significant). No difference was found between patients with new-onset AF and those without AF. During follow-up (2.6 +/- 1.9 years), more patients with persistent AF received appropriate ICD shocks as compared with those without AF (24 [38%] vs 49 [24%], P = .04). Deterioration of CHF occurred more often in patients with persistent AF (19 [30%], P = .001) and those with new-onset AF (9 [47%], P < .001) as compared with patients without AF (31 [14%]). Multivariate analysis revealed that patients with persistent AF had an increased risk for appropriate ICD shocks (adjusted hazard ratio [HR] 1.9, 95% CI 1.2-3.2, P = .009). Persistent AF (adjusted HR 2.1, 95% CI 1.1-3.9, P = .03) and new-onset AF (adjusted HR 2.5, 95% CI 1.1-5.7, P = .02) were found to be independent risk indicators of CHF deterioration.</AbstractText>In ICD patients with left ventricular dysfunction, persistent AF is associated with appropriate ICD shocks and deterioration of CHF. New-onset AF is related to deterioration of CHF.</AbstractText> |
9,066 | Atrial fibrillation in heart failure patients: prevalence in daily practice and effect on the severity of symptoms. Data from the ALPHA study registry. | Estimates of the prevalence of atrial fibrillation (AF) in heart failure (HF) originate from patients enrolled in clinical trials.</AbstractText>To assess the prevalence and clinical correlates of AF among HF patients in everyday clinical practice from HF patients screened for the T-wave ALternans in Patients with Heart fAilure (ALPHA) study; to investigate the correlation between AF and functional status.</AbstractText>Consecutive patients (N=3513) seen at nine Heart Failure Clinics were studied; 21.4% were in AF. AF prevalence was greater with increasing age (OR 1.04/year, p<0.001) in non-ischaemic cardiomyopathy (OR 2.34, p<0.001) and with increasing NYHA class (p<0.0001). Multiple logistic regression predictors of AF were age >70 years (OR 2.35), NYHA class II III or IV vs class I (OR 1.8, 4.4 and 3.1) and non-ischaemic cardiomyopathy (OR 3.2). A logistic model indicated that AF was associated with a 2.5 OR of being in NYHA class III-IV vs I-II while accounting for age, gender, left ventricular ejection fraction (LVEF), and aetiology of HF.</AbstractText>The prevalence of AF in HF patients exceeds 20%, and increases with age and functional class. The presence of AF leads to a more severe NYHA class, indicating that AF contributes to the severity of heart failure.</AbstractText> |
9,067 | Hemodynamic and neurohormonal predictors and consequences of the development of atrial fibrillation in dogs with chronic heart failure. | Heart failure increases the risk of atrial fibrillation (AF), which frequently results in heart failure progression. This prospective study examined the contribution of hemodynamic and neurohormonal activation to the spontaneous occurrence of AF in heart failure, and assessed the effects of AF on left ventricular (LV) function and neurohormonal activation.</AbstractText>Heart failure (LV ejection fraction [LVEF] 25%-30%) was induced in 27 dogs via sequential coronary microembolizations. Hemodynamic and neurohormonal measurements were performed at 1 month (prior to development of AF) and 4 months post-embolization. During the time between measurements, 10 dogs developed spontaneous AF. Plasma norepinephrine concentration (PNE) at 1 month was higher in animals that subsequently developed AF (576 + 101 vs. 425 + 197 pg/mL, P = .03). There were no significant differences between the groups in 1-month LV end-diastolic pressure (LVEDP), pulmonary artery wedge pressure (PAWP), cardiac output, end-diastolic volume (EDV), LVEF, or plasma renin activity (PRA). At 4 months, cardiac output was lower (2.1 + .4 vs. 2.6 + .6 L/h, P = .02) and PNE was higher (1036 + 857 vs. 508 + 288 pg/mL, P = .03) in dogs with AF versus those in sinus rhythm. There were no significant differences between groups in 4-month LVEDP, PAWP, EDV, LVEF, or PRA.</AbstractText>Spontaneous AF in heart failure was preceded by a significant increase in PNE. In animals that developed AF, there was a further decline in cardiac output and increase in PNE.</AbstractText> |
9,068 | Role of Purkinje fibers in post-infarction ventricular tachycardia. | The objective of this study was to assess the role of Purkinje fibers in monomorphic, post-infarction ventricular tachycardia (VT).</AbstractText>Ventricular fibrillation and polymorphic VT in the setting of acute myocardial infarction (MI) may be triggered by ectopy arising from Purkinje fibers.</AbstractText>From among a group of 81 consecutive patients with post-infarction monomorphic VT referred for catheter ablation, 9 patients were identified in whom the clinical VT had a QRS duration < or =145 ms. Mapping was performed focusing on areas with Purkinje potentials.</AbstractText>A total of 11 VTs with a QRS duration < or =145 ms were induced and mapped in the 9 patients; 9 of the 11 VTs had a right bundle branch block/left-axis morphology that mimicked left posterior fascicular VT. The mean VT cycle length was 402 +/- 82 ms. Eight of 9 patients had a history of inferior MI involving the left ventricular septum. One patient had an anterior wall MI with septal involvement. Mapping during VT demonstrated re-entry involving the inferior left ventricular wall. In each of the VTs, a Purkinje potential was present at the exit site of the VT re-entry circuit. Single radiofrequency catheter ablation lesions were successful in eliminating these VTs in all patients.</AbstractText>The Purkinje system may be part of the re-entry circuit in patients with post-infarction monomorphic VT, resulting in a type of VT with a relatively narrow QRS complex that mimics fascicular VT.</AbstractText> |
9,069 | Clinical syndrome suggestive of heart failure is frequently attributable to non-cardiac disorders--population-based study. | To assess how often the clinical syndrome (CS) of heart failure is attributable to alternative, including non-cardiac, explanations.</AbstractText>Cross-sectional evaluation of 739 community participants aged>or=45 years. Subjects with >or=2 symptoms or signs (dyspnoea or fatigue, orthopnoea, nocturnal paroxysmal dyspnoea, third heart sound, jugular venous distension, rales and lower limb oedema) or who were receiving loop diuretics were considered to have the clinical syndrome of heart failure. Attributable fractions were derived based on adjusted odds ratios and the prevalence of underlying disorders among cases. CS was present in 28.0% of women and in 15.2% of men, p<0.001. The multivariate-adjusted fraction of CS attributable to female gender was 40.6%, to age>or=65 years 28.5%, left ventricular systolic dysfunction, left ventricular dilatation or moderate-severe valvular disease 4.9%, diastolic dysfunction or atrial fibrillation 13.0%, obesity 22.6%, coronary heart disease 7.2% and chronic lung disease 6.9%. When additionally adjusting for depressive symptoms, the association with gender and age became much weaker, and 32% of cases were attributable to depressive symptoms. Forty-two percent of subjects with CS had cardiac abnormalities.</AbstractText>In less than half of subjects with CS was systolic or diastolic heart failure confirmed. Female gender, older age, obesity and depressive symptoms accounted for the largest fraction of CS.</AbstractText> |
9,070 | Antithrombotic and interventional treatment options in cardioembolic transient ischaemic attack and ischaemic stroke. | Peer-reviewed data pertaining to anti-thrombotic and interventional therapy for transient ischaemic attack (TIA) or ischaemic stroke patients with non-valvular atrial fibrillation, atrial flutter, interatrial septal abnormalities, or left ventricular thrombus were reviewed. Long-term oral anticoagulant therapy with warfarin is the treatment of choice for secondary stroke prevention following TIA or minor ischaemic stroke in association with persistent or paroxysmal non-valvular atrial fibrillation or atrial flutter. If warfarin is contraindicated, long-term aspirin is a safe, but much less effective alternative treatment option in this subgroup of patients with cerebrovascular disease. Management of young patients with TIA or stroke in association with an interatrial septal defect is controversial. Various treatment options are outlined, but readers are encouraged to include these patients in one of the ongoing randomised clinical trials in this area. It is reasonable to consider empirical anticoagulation in patients with TIA or ischaemic stroke in association with left ventricular thrombus formation following myocardial infarction or in association with idiopathic dilated cardiomyopathy. If warfarin is prescribed, one should aim for a target international normalised ratio of 2.5 (range 2-3) to achieve the best balance between adequate secondary prevention of cardioembolic events and the risk of major haemorrhagic complications. |
9,071 | [Electrical storms in patients with implantable cardioverter-defibrillator: incidence and clinical management]. | Electrical storm in implantable cardioverter-defibrillator (ICD) recipients is a dramatic experience for the patient and a hard emergency for the cardiology team. The aim of our study was to evaluate the incidence and the clinical significance of electrical storm in a standard population of ICD patients.</AbstractText>We considered retrospectively 262 consecutive ICD patients (86% males, mean age 65+/-10.7 years). Patients were divided into three groups: 88 patients without appropriate ICD therapy (group A); 140 patients with isolated ICD therapies (group B); 34 patients with electrical storm episodes (> or = 3 appropriate ICD therapies/24 h) (group C). Survival study (endpoint death) was performed for each group of patients.</AbstractText>There was no difference in age, sex, heart disease, ejection fraction or NYHA functional class among the three groups. ICD implant was performed for secondary prevention in 79% of group C patients and in 74.3 % of group B patients, but only in 39.8 % of group A patients (p < 0.0001). Mean follow-up was 31.1+/-29.8 months in group A, 55.1+/-38 months in group B, and 71.1+/-51.7 months in group C. The endpoint was reached by 16 patients (18%) of group A, by 53 patients (38%) of group B, and by 20 patients (58%) of group C. Comparison of the survival curves of the three groups did not show significant differences. In group C patients, 54 electrical storm episodes were recorded (mean 1.5/patient).</AbstractText>In our population of ICD patients, we observed electrical storm in 34 patients (12.9%). Survival in group with episodes of electrical storm was comparable to patients without electrical storm; thus, in our experience, electrical storm could not represent a negative prognostic factor.</AbstractText> |
9,072 | [Italian Network on Congestive Heart Failure: ten-year experience]. | IN-CHF is a multicenter registry, designed in 1995 to compile a large clinical database on the epidemiological, clinical characteristics, management and outcomes of heart failure outpatients. Main objectives of IN-CHF registry were to provide cardiological centers with a software to collect data of outpatients during office visit, for educational purpose; and to enter local data into a national registry (IN-CHF registry), for scientific purpose. Entry into the database required a diagnosis of heart failure according to the guidelines of the European Society of Cardiology. The central coordinator of the project was the ANMCO Research Center. The Italian cardiological centers participating in the project are 142, they are well representing the entire country and from March 1995 to July 2005 collected data from 23 855 outpatients. The mean age of the patients was 65+/-13 years and 71.3% were men. Main etiologies were ischemic in 39.4%, hypertensive in 15.8 %, and due to dilated cardiomyopathy in 29%. More than half of the patients (55.3%) had a history of admission for heart failure within the last year; 25.8% of the patients were in NYHA class III-IV, 9.5% showed a heart rate > 100 bpm and 16.5% third heart sound. Left ventricular ejection fraction was severely depressed (< 30%) in 27.6% of the patients, while it was > 40% in 30.9%. Renal dysfunction was present in 3.6% of the patients (serum creatinine level > 2.5 mg/dl), pulmonary disease in 18.7%, diabetes in 16.8% and anemia (hemoglobin < 12 g/dl) in 18.7%. A history of arterial hypertension was common (30.3%); 20.0% and 18.5% of the patients showed atrial fibrillation and left bundle branch block, respectively. Data from our registry provide important insights into clinical and epidemiological characteristics of heart failure outpatients followed in Italian cardiological centers. Starting from this article, every 3 months, the most relevant epidemiological data collected by the IN-CHF investigators will be published. |
9,073 | Using geographic information systems to evaluate cardiac arrest survival. | To evaluate cardiac arrest survival using geographical information systems (GIS) methodology.</AbstractText>Patient data were obtained from a fire district Utstein-style adult cardiac arrest registry that also included address data. All incident locations were geocoded and fire station first-due areas were mapped by using the new computer-aided dispatch geographic data. Retrospective assignment of first-due versus second-due fire response unit was done by using a GIS "point-in-polygon" algorithm Survival to hospital admission was the primary outcome measure for incidents responded to by first-due versus second-due apparatus controlling for other potential predictors of survival using logistic regression. Cluster analysis was also performed to evaluate potential areas of high or low rates of survival.</AbstractText>There were 461 eligible patients with an average age of 67+/-17 years, 63% were male, 53% had a witnessed arrest, bystander cardiopulmonary resuscitation was performed in 38%, bystander automatic external defibrillator (AED) Page: 1 was used in 0.01%, ventricular fibrillation or ventricular tachycardia were the presenting rhythms in 44%, the average response time was 5.5+/-2.1 minutes, and survival to hospital admission was 17%. There was no significant difference in response time between survivors (4.97 minutes) and non-survivors (5.52 minutes), (difference 0.55 minutes, 95%CI -0.08 to 1.18 min). The number of cardiac arrest calls varied from 1 to 49 for each station and the rate of second-due response varied from 0 to 19%. There was a nonsignificant association of survival to hospital admission for the first-due area cohort: odds ratio 0.70, 95% CI 0.38-1.29.</AbstractText>GIS is a new methodology for analyzing EMS incident data. It adds a spatial component of analysis to traditional statistical techniques. No spatial difference was found on patient survival in this analysis.</AbstractText> |
9,074 | Physiologic pacing: new modalities and pacing sites. | Right ventricular (RV) apical pacing impairs left ventricular function by inducing dys-synchronous contraction and relaxation. Chronic RV apical pacing is associated with an increased risk of atrial fibrillation, morbidity, and even mortality. These observations have raised questions regarding the appropriate pacing mode and site, leading to the introduction of algorithms and new pacing modes to reduce the ventricular pacing burden in dual chamber devices, and a shift of the pacing site away from the RV apex. However, further investigations are required to assess the long-term results of pacing from alternative sites in the right ventricle, because long-term results so far are equivocal. The potential benefit of prophylactic biventricular, mono-chamber left ventricular, and bifocal RV pacing should be explored in selected patients with a narrow QRS complex, especially those with impaired left ventricular function. His bundle pacing is a promising and evolving technique that requires improvements in lead technology. |
9,075 | Optimization of pacing algorithms to prevent and treat supraventricular tachyarrhythmias. | Preventive atrial pacing and antitachycardia pacing have been proposed for the treatment of atrial fibrillation and associated arrhythmias in patients with indications for device implantation. Preventive algorithms provide overdrive atrial pacing, reduction of atrial premature beats, and prevent short-long atrial cycles with good patient tolerance. However, clinical trials testing preventive algorithms have shown contradictory results, possibly because of different trial designs, end points and patient populations. Factors probably responsible for neutral results include an already high atrial pacing percentage with the conventional DDDR mode, suboptimal atrial pacing site, and the deleterious effects of high percentages of right ventricular apical pacing. Atrial antitachycardia pacing therapies are effective in treating organized atrial tachyarrhythmias (that precede atrial fibrillation), mainly when delivered early after the onset particularly if the tachycardia is relatively slow. Antitachycardia pacing therapies might influence atrial fibrillation burden, but clinical studies have shown conflicting results about this issue. Consistent monitoring of atrial and ventricular rhythm including progression to persistent forms of atrial arrhythmias, variability of atrial arrhythmia recurrence patterns and onset mechanisms as well as antitachycardia pacing efficacy should be recorded in the stored device memory and used for optimal individual programming of these new functions. |
9,076 | Atrial tachyarrhythmias in primary and secondary prevention ICD recipients: clinical and prognostic data. | Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. The natural history of this disturbance and its effect on survival is still not known in patients with implantable cardioverter defibrillators (ICDs).</AbstractText>Several controlled trials for both secondary and primary prevention of sudden death using ICDs have been published in literature, and meta-analysis of them provided useful clinical information on the outcome during the follow-up of this population. AF occurs in about 25% of the patients with secondary prevention indication for ICD implantation. The prevalence of AF in patients with primary prevention indication for ICD implantation is much more difficult to define; it seems to be higher in patients with left ventricular dysfunction due to nonischemic etiology (ranging from 15% to 25%), and is lower in patients with ischemic etiology (about 5-10%). However, data from clinical registries, which are expected to better reflect clinical practice than randomized trials, seem to show a substantial difference as compared to the latter ones. A history of AF episodes in patients with an ICD indication for both primary and secondary prevention is probably associated with a higher risk of death. This is particularly evident in secondary prevention in ICD recipients, while it is still controversial in patients who received an ICD for primary prevention, particularly when patients with nonischemic etiology of their left ventricular dysfunction are considered. In a population of patients implanted with an ICD, there are several other clinical factors (ejection fraction, New York Heart Association functional class, age) that can interfere with the risk of death much more than AF itself.</AbstractText>Further large-scale registries are needed to further characterize the population receiving ICD implantation, assessing the course of risk of death with regard to clinical variables and to evaluate the degree of acceptance of trials in clinical practice.</AbstractText> |
9,077 | Hybrid therapies for ventricular arrhythmias. | In recent years several trials demonstrated the efficacy of implantable cardioverter-defibrillation (ICD) therapy in reducing cardiac and total mortality in patients affected by rapid ventricular tachycardia (VT) and/or ventricular fibrillation. Nevertheless, ICD do not prevent arrhythmia recurrences, thus being a palliative and not a curative treatment modality. The tolerance to ICD therapy varies greatly, and within individuals, this leading to a nonuniform acceptance of this form of therapy. The very frequent occurrence of VT, defined as an arrhythmic storm, may be a life threatening condition. The majority of ICD patients is under antiarrhythmic drug therapy, to reduce episodes of VT or to make antitachycardia pacing more effective by slowing the tachycardia rate. Drug therapy, however, may cause additional problems, and does not represent the optimal solution. The prevention of VT and/or ventricular fibrillation episodes and excessive ICD therapy, remains a worthwhile goal. Radiofrequency catheter ablation (RFCA) is a curative approach, and can be expected to reduce the frequency of recurrent VT episodes in the majority of patients. The combination of these treatment modalities (ICD and RFCA) is often described as hybrid therapy, implying that the two treatments act providing some form of synergism. In experienced centers, RFCA is now performed, regardless of whether the VT rate is rapid and/or is hemodynamically unstable. Newer mapping and ablation techniques are now available, enhancing the acute success rate of the procedure. In this review the most recent application of VT catheter ablation and the use of advanced mapping and ablation techniques will be discussed. |
9,078 | Impact of the main implantable cardioverter-defibrillator trials for primary and secondary prevention in Italy: a survey of the national activity during the years 2001-2004. | Several trials demonstrated the lifesaving role of implantable cardioverter-defibrillator (ICD) in high-risk groups of patients. Aim of this review was to report the clinical characteristics of patients enrolled in the ICD Registry of the Italian Association of Arrhythmology (AIAC) in the years 2001-2004.</AbstractText>The Registry collects prospectively 85% of national ICD implantation activity on the basis of European ICD form (EURID).</AbstractText>The number of implanted ICDs in Italy was 2,418 in the year 2001, 3,992 in the year 2002, 5,595 in the year 2003, and 7,190 in the year 2004. The number of ICDs per million of inhabitants was 42.1 in the year 2001 (+11.8% respect to 2000), 70.0 in the year 2002 (+65.1% respect to 2001), 98.3 in the year 2003 (+40.4% respect to 2002), and 125.0 in the year 2004 (+27.2% respect to 2003). The median age was 67 years in the years 2001-2002, 68 years in the years 2003-2004. The main indications during the study were syncope (24.2-14.9%) and cardiac arrest (28.5-17.3%), followed by palpitations and dizzy spells (15.5-17.2%, and 9.4-6.9% of patients, respectively). The use of prophylactic ICD had a fourfold increase in the examined period (5.8% in 2001, 22.9% in 2004). Ventricular tachycardia was the main arrhythmic indication in 44.4-54.6% of cases, ventricular fibrillation in 11.8-18.0%, both in 3.5-6.5%. In the years 2002, 2003, and 2004 single chamber ICDs were implanted in 45.5%, 38.8%, and 33.7% of patients, dual chamber ICDs in 35.1%, 32.3%, and 30.5%, biventricular ICDs in 19.4%, 28.9%, and 34.7%, respectively.</AbstractText>The ICD implantation rate in Italy increased significantly in the period 2001-2004, similarly to the trend in other western countries. The Registry showed an important increase of prophylactic and dual or triple chamber ICDs use.</AbstractText> |
9,079 | Myocardial ischemia and ventricular fibrillation: pathophysiology and clinical implications. | Ventricular fibrillation (VF) and myocardial ischemia are inseparable. The first clinical manifestation of myocardial ischemia or infarction may be sudden cardiac death in 20-25% of patients. The occurrence of potentially lethal arrhythmia is the end result of a cascade of pathophysiological abnormalities that result from complex interactions between coronary vascular events, myocardial injury, and changes in autonomic tone, metabolic conditions and ionic state of the myocardium. It is also related to the time from the onset of ischemia. Within the first few minutes there is abundant ventricular arrhythmogenesis usually lasting for 30 min. Triggers for ischemic VF occur at the border zone or regionally ischemic heart. The border zone of ischemia is the predominant site of fragmentation. Acute ischemia opens K(ATP) channels and causes acidosis and hypoxia of myocardial cells leading to a large dispersion in repolarization across the border zone. Abnormalities of intracellular Ca2+ handling also occur in the first few minutes of acute myocardial ischemia and may be an important cause of arrhythmias in human coronary artery disease. Substrate on the other hand transforms triggers into VF and serves to maintain it through fragmentation of waves in the ischemic zone. Thrombin levels, stretch, catecholamine, genetic predisposition, etc. are some of these factors. Reentry models described are spiral wave reentry, 3 dimensional rotors, reentry around 'M' cells and figure-of-eight reentry. Continuing efforts to better understand these arrhythmias will help identify patients of myocardial ischemia prone to arrhythmias. |
9,080 | [Cardioverter-defibrillator implantation in a patient with persistent left superior vena cava--a case report]. | A case of a successful implantation of cardioverter-defibrilator using the persistent left superior vena cava is presented. After six month of follow-up pacing and sensing parameters remained constant. |
9,081 | Atrial fibrillation in hypertrophic cardiomyopathy: mechanisms, embolic risk and prognosis. | Hypertrophic cardiomyopathy (HCM) is associated with an increased incidence of supraventricular and ventricular arrhythmias. Atrial fibrillation (AF) is the most common arrhythmia in HCM with a prevalence of 20% and an annual incidence of two percent per year. Increased left atrial size and volume along with impaired left atrial function confer an increased likelihood of AF. The onset of AF is often accompanied by a decrease in functional status in conjunction with an increased risk of stroke and overall mortality. |
9,082 | Right ventricular pacing and the risk of heart failure in implantable cardioverter-defibrillator patients. | Right ventricular (RV) pacing in implantable cardioverter-defibrillator (ICD) patients may have detrimental effects on morbidity and mortality, in particular by inducing heart failure (HF).</AbstractText>We investigated whether RV pacing increases the risk of HF in an asymptomatic ICD population.</AbstractText>We evaluated all patients without symptomatic HF who received an ICD. The primary endpoint was the occurrence of HF, which was defined as new HF, hospitalization for HF, or death due to HF. The secondary endpoint was appropriate shocks.</AbstractText>The study population consisted of 456 patients with mean left ventricular ejection fraction (LVEF) 40% +/- 13%. Mean follow-up was 31 +/- 22 months. Because of the bimodal distribution of pacing, patients were divided into two groups: paced <or=50% (median 0%; n = 313) and paced >50% (median 96%; n = 143). HF occurred more often in the paced >50% group (20% versus 9%; P <.001). Multivariate analysis identified RV pacing >50% (adjusted hazard ratio [HR] 1.85; 95% confidence interval [CI] 1.08-3.15; P = .03), baseline LVEF <26% (adjusted HR 3.15; 95% CI 1.77-5.59; P <.001), angina pectoris, history of atrial fibrillation, and baseline diuretic use as independent predictors of HF. RV pacing caused more HF events in patients with LVEF <26% (n = 64; 55% of paced >50% patients versus 20% of paced <or=50% patients; P = .006). RV pacing >50% also independently predicted appropriate shocks (adjusted HR 1.50; 95% CI 1.02-2.20; P = .04).</AbstractText>RV pacing was associated with an increased risk of HF in asymptomatic ICD patients, particularly in those with preexistent left ventricular dysfunction.</AbstractText> |
9,083 | Utstein style analysis of out-of-hospital cardiac arrest--bystander CPR and end expired carbon dioxide. | The aim of this prospective cohort study was to describe the outcome for patients with out-of-hospital cardiac arrest in Maribor (Slovenia) over a 4 year period using a modified Utstein style, and to investigate elementary knowledge of basic life support among potential bystanders in our community.</AbstractText>Through the prehospital and the hospital database system we followed up a consecutive group of patients with out-of-hospital cardiac arrest (OHCA) between January 2001 and December 2004. We investigated the effects of various factors on outcome in OHCA, especially partial end-tidal CO2 pressure (petCO2), efficacy of bystander CPR and their elementary knowledge of basic life support (BLS). We also examined motivation among potential bystanders and possible implementation for BLS education in our community.</AbstractText>OHCA was confirmed in 592 patients. Advanced cardiac life support was initiated in 389 patients, of which 277 were of cardiac aetiology. In 287 patients the event was bystanders witnessed and lay-bystander basic life support was performed only in 83 (23%). After treating OHCA by a physician-based prehospital medical team ROSC was obtained in 61%, the ROSC on admission was 50% and the overall survival to discharge was 21%. Initial petCO2 (OR: 22.04; 95%CI: 11.41-42.55), ventricular fibrillation or pulseless ventricular tachycardia as initial rhythm (OR: 2.13; 95%CI: 1.17-4.22), bystander CPR (OR: 2.55; 95%CI: 1.13-5.73), female sex (OR: 3.08; 95%CI: 1.49-6.38) and arrival time (OR: 1.29; 95%CI: 1.11-1.82) were associated with improved ROSC when using multivariate analysis. Using the same method we found that bystander CPR (OR: 5.05; 95%CI: 2.24-11.39), witnessed arrest (OR: 9.98; 95%CI: 2.89-34.44), final petCO2 (OR: 2.37; 95%CI: 1.67-3.37), initial petCO2 (OR: 1.61; 95%CI: 1.28-2.64) and arrival time (OR: 1.39; 95%CI: 1.33-1.60) were associated with improved survival. A questionnaire to potential bystanders has revealed disappointing knowledge about BLS fundamentals. On the other side, there is a welcomed willingness of potential bystanders to take BLS training and to follow dispatchers instructions by telephone on how to perform CPR.</AbstractText>After OHCA in a physician-based prehospital setting in our region, the overall survival to discharge was 21%. The potential bystander in our community is generally poorly educated in performing CPR, but willing to gain knowledge and skills in BLS and to follow dispatchers instructions. Arrival time, witnessed arrest, bystander CPR, initial petCO2 and final petCO2 were significantly positively related with ROSC on admission and with survival. Prehospital data from this and previous studies provide strong support for a petCO2 of 1.33 kPa to be a resuscitation threshold in the field. In our opinion the initial value of petCO2 should be included in every Utstein style analysis.</AbstractText> |
9,084 | Real-time detection and alerting for acute ST-segment elevation myocardial ischemia using an implantable, high-fidelity, intracardiac electrogram monitoring system with long-range telemetry in an ambulatory porcine model. | The purpose of this study was to evaluate feasibility of using real-time, high-fidelity, intracardiac electrogram monitoring from a permanently implantable ischemia detection system (IIDS), with long-range telemetry capability to detect ST-segment shifts associated with acute or subacute coronary occlusion in a porcine model.</AbstractText>Early identification of coronary occlusion with ST-segment elevation could profoundly accelerate the timing of revascularization and improve clinical outcomes.</AbstractText>This paper reports the first investigation using real-time, high-fidelity, intracardiac electrogram monitoring from a permanently IIDS, with long-range telemetry capability. This IIDS was tested in an ambulatory porcine model, with acute coronary occlusion precipitated by stent thrombosis. Two overlapping copper stents were implanted in the left anterior descending (n = 3), the circumflex (n = 3), or the right coronary artery (n = 2) of juvenile farm pigs. Monitoring was carried using telemetry from the IIDS.</AbstractText>All stented pigs had acute ST-segment elevation event(s) triggering the alerting thresholds of the IIDS. All triggered events were confirmed to be caused by thrombosis of the copper stent(s), and well correlated to infarct age and location. Four of the 8 pigs died from ventricular fibrillation, recorded by the IIDS at a mean time of 70 +/- 121 h after ST-segment alert. The sensitivity and specificity of alerting for ST-segment shift, associated with thrombotic coronary occlusion, were 100% and 100%, respectively.</AbstractText>This study demonstrates the ability of an implantable ischemia detection system to detect ST-segment elevation from coronary occlusion in a porcine model of ST-segment elevation myocardial infarction. ST-segment elevation was sufficient to trigger alerting thresholds in all 3 epicardial coronary distributions. Such a system, with real-time alerting capability, could advance the time frame of reperfusion therapy and potentially prevent, rather than interrupt, acute myocardial infarction in patients with coronary artery disease.</AbstractText> |
9,085 | Effect of defibrillation testing on management during implantable cardioverter-defibrillator implantation. | Verification of defibrillation efficacy by defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator implantation is the current standard. Generally, defibrillation of ventricular fibrillation at 10 J below the maximum output of a device is felt to establish an adequate safety margin. Nonetheless, DFT testing adds to cost and carries some potential for morbidity, whereas its impact on outcomes in the modern era of defibrillator technology is unclear. We aimed to determine the frequency that DFT testing resulted in a change at device implant and to identify clinical and echocardiographic predictors of the need for DFT testing.</AbstractText>We reviewed all implantable cardioverter-defibrillators that were implanted at the London Health Sciences Centre (Ontario, Canada) from June 1999 to August 2003 and used multivariate analysis to determine variables associated with DFT test failures and elevated DFT values. When a defibrillation failure was not observed, a lowest energy to defibrillate (LED) was recorded.</AbstractText>Among 168 implants, DFT testing was successful with a minimum 10-J safety margin in 152 (90%), whereas the remaining 16 required changes at device implant. In a multivariate analysis, use of amiodarone was independently associated with DFT failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.0). Significantly higher mean DFT/LED values were observed among patients on amiodarone (1.36 J; P = .0041). Those with nonischemic cardiomyopathy had a higher mean DFT/LED compared with those with ischemic cardiomyopathy (1.44 J; P = .028).</AbstractText>Use of amiodarone is associated with a 4-fold increase in risk of DFT failure and subsequent need for changes at implant to achieve a safe threshold. Defibrillation threshold testing appears to be most useful for patients taking amiodarone.</AbstractText> |
9,086 | [On the possibility of amiodarone use in some cases of persistent atrial fibrillation]. | Aim of the study was to investigate mechanisms of amiodarone action on atrial and ventricular rhythm during persistent atrial fibrillation (PAF), and to assess efficacy of amiodarone as monotherapy or in combination with digoxin. Holter ECG monitoring and registration of high resolution ECG with construction of periodograms of ff waves and histograms of RR intervals (MATLAB 5.3 environment) were carried out in 34 patients (mean age 63.1+/-11.0 years) with PAF. Amiodarone (550.0+/-143.4 mg/day), digoxin (0.30+/-0.09 mg/day) with amiodarone (571.4+/-106.9 mg/day) were given for 21 days with recordings of high resolution ECG at baseline and on day 21. Long term therapy (1.7 years) with combination of digoxin 0.19+/- 0.07 mg/day) and amiodarone (254+/-82.0 mg/day) was controlled by Holter ECG monitoring. Monotherapy with amiodarone was not associated with significant lowering of heart rate (HR) (small er, Cyrillic=0.054) because of complex effect of amiodarone of HR: significant increase of period of ff waves (by 0.031+/-0.011 s), with facilitation of their conduction to ventricles combined with significant 0.10+/-0.08 s increment of minimal RR. Amiodarone combined with digoxin caused significantly lesser (by 0.009+/-0.017 s) enlargement of ff waves and significant lowering of HR (by 21.24+/-15.77 bpm) at the account of slowing of AV conduction (minimal RR increased by 0.12+/-0.08 s) and suppression of early RR peaks (0.28-0.46 s). The combination effectively suppressed tachysystolia resistant to other therapy (maximal HR 170-215 bpm) with significant lowering of mean (by 16.5+/-13.1 bpm) and maximal (by 43.3+/-35.6 s) HR, with suppression of ventricular extrasystoles in 83% of patients, and without significant lowering of minimal HR and appearance of pauses from 3 s. Level of thyrotrophic hormone rose from 2.4 to 5/9 IU/ml (p >0.05). |
9,087 | Effect of acetylcholine and ischaemia/reperfusion injury on the heart of rats with STZ-induced experimental diabetes. | To investigate the effect of acetylcholine (ACh) and ischaemia/reperfusion injury on functional changes and dysrhythmias of the isolated diabetic rat heart.</AbstractText>On retrogradely perfused hearts isolated from 10-week-old diabetic rats (streptozotocin 30 mg/kg b.w. for three consecutive days i.p.), two types of experiments were done: /1/ The effect of acetylcholine (ACh; 3 x 10(-7) mol/l) was evaluated both during and after infusion, and /2/ the influence of the ischaemia/reperfusion injury (I/R) was studied. At the end of both experiments the hearts were electrically stimulated to evoke sustained ventricular fibrillation (VF). An increase of coronary arterial pressure, bradycardia and decreased total number of severe dysrhythmias of both types, spontaneous and evoked ones, were recorded in the diabetic hearts. ACh increased the force of contraction (LVP) and induced vasoconstriction, which persisted in the diabetic hearts even after removal of ACh from the perfusion solution.</AbstractText>The isolated diabetic rat heart was more resistant against severe dysrhythmias. After washing out the ACh, the vasoconstriction of coronary arteries still lasted, along with increased inotropic effect on the left ventricle.</AbstractText> |
9,088 | Increasing use of cardiopulmonary resuscitation during out-of-hospital ventricular fibrillation arrest: survival implications of guideline changes. | The most recent resuscitation guidelines have sought to improve the interface between defibrillation and cardiopulmonary resuscitation; the survival impact of these changes is unknown, however. A year before issuance of the most recent guidelines, we implemented protocol changes that provided a single shock without rhythm reanalysis, stacked shocks, or postdefibrillation pulse check, and extended the period of cardiopulmonary resuscitation from 1 to 2 minutes. We hypothesized that survival would be better with the new protocol.</AbstractText>The present study took place in a community with a 2-tiered emergency medical services response and an established system of cardiac arrest surveillance, training, and review. The investigation was a cohort study of persons who had bystander-witnessed out-of-hospital ventricular fibrillation arrest because of heart disease, comparing a prospectively defined intervention group (January 1, 2005, to January 31, 2006) with a historical control group that was treated according to previous guidelines of rhythm reanalysis, stacked shocks, and postdefibrillation pulse checks (January 1, 2002, to December 31, 2004). The primary outcome was survival to hospital discharge. The proportion of treated arrests that met inclusion criteria was similar for intervention and control periods (15.4% [134/869] versus 16.6% [374/2255]). Survival to hospital discharge was significantly greater during the intervention period compared with the control period (46% [61/134] versus 33% [122/374], P=0.008) and corresponded to a decrease in the interval from shock to start of chest compressions (28 versus 7 seconds). Adjustment for covariates did not alter the survival association.</AbstractText>These results suggest the new resuscitation guidelines will alter the interface between defibrillation and cardiopulmonary resuscitation and in turn may improve outcomes.</AbstractText> |
9,089 | Acute volume overload elevates T-wave alternans magnitude. | The objective of this study was to determine whether acute volume loading elevates T-wave alternans (TWA) in dogs with structurally normal hearts. TWA predicts sudden cardiac arrest in patients with left ventricular dysfunction and congestive heart failure. However, volume load and ventricular stretch may themselves precipitate arrhythmias. It is unclear to what extent volume load causes TWA. In six male mongrel dogs [25.8 kg (SD 4.2)] under general anesthesia, we measured TWA during progressive atrial pacing to 160 beats/min. Pacing was performed at baseline, at the midpoint and peak of a saline infusion designed to induce acute CHF, and then during diuresis. Dog 1 was hypothermic throughout the protocol and excluded from analysis. For dogs 2-6, 102 ml/kg (SD 30) were infused over 315 min (SD 50), causing pulmonary capillary wedge pressure to rise from 9.6 (SD 3.5) to 21.2 mmHg (SD 1.6) (P < 0.01), and heart rate variability to fall (P < 0.01). TWA magnitude (Valt) rose in all dogs with volume load (P < 0.001). Compared with baseline, TWA at peak infusion had higher magnitude [Valt 3.4 (SD 1.95) vs. 0.5 muV (SD 0.35); P = 0.011] and occurred at lower heart rates [128 (SD 6) vs. 151 beats/min (SD 12); P = 0.008]. Net volume load was linearly related to Valt (P < 0.01), with each 10 ml/kg net volume load increasing Valt by 0.23 muV. Acute volume overload elevates TWA in normal canine hearts. Although dramatic, however, this effect may contribute clinically to abnormal TWA only in patients with marked volume overload. Future studies should examine the interaction of fluid overload, myocardial disease, and arrhythmia susceptibility. |
9,090 | Blockade of atrial-specific K+-currents increases atrial but not ventricular contractility by enhancing reverse mode Na+/Ca2+-exchange. | AVE0118 (2'-{[2-(4-Methoxy-phenyl)-acetylamino]-methyl}-biphenyl-2-carboxylic acid (2-pyridin-3-yl-ethyl)-amide) blocks atrial ultrarapid delayed rectifier currents (I(Kur)) and prolongs the atrial action potential (AP) plateau without affecting ventricular repolarisation. In patients with atrial contractile dysfunction due to atrial tachyarrhythmias, this response might increase atrial contractility without risk of ventricular proarrhythmia. This study was designed to evaluate the inotropic mechanisms of AVE0118.</AbstractText>In isometrically contracting atrial trabeculae, AVE0118 increased contractile force by 55.4% in sinus rhythm patients (n = 9) and by 107.4% in patients with atrial fibrillation (n = 8). In freshly isolated canine atrial myocytes studied under perforated patch current clamp (37 degrees C), AVE0118 increased myocyte fractional shortening from 3.8+/-0.6 to 9.6+/-0.8% and prolonged action potential duration at 30% repolarisation from 9+/-2 to 102+/-11 ms. Clamping cells to an AP waveform recorded during exposure to AVE0118 produced the same inotropic response as the drug itself. In action potential clamp, peak Ca2+ inward current (I(CaL)) current declined from 5.5+/-1.3 pA/pF during control to 4.1+/-0.7 pA/pF when an AP recorded in the presence of AVE0118 was used as command waveform. However, I(CaL) was more sustained with AVE0118 and the time integral did not change (135+/-37 vs. 173+/-30 pA/pFms, p = ns). Importantly, blockade of reverse mode Na+/Ca2+-exchanger activity with 5 microM KBR7943 or using a Na+-free pipette solution abolished the positive inotropic effect of the AP recorded in the presence of AVE0118. In ventricular myocytes AVE0118 did not elicit a positive inotropic response.</AbstractText>Block of I(Kur) by AVE0118 enhances atrial contractility both in patients with sinus rhythm and atrial fibrillation. The positive inotropic effect is atrial-specific and due to the changes of the action potential configuration which enhances Ca2+ entry via reverse mode Na+/Ca2+ exchange.</AbstractText> |
9,091 | [Pediatric advanced life support]. | Advanced life support (ALS) includes all the procedures and maneuvers used to restore spontaneous circulation and breathing, thus minimizing brain injury. The fundamental steps of ALS are airway control with adjuncts, ventilation with 100% oxygen, vascular access and fluid and drug administration, and monitoring to diagnose and treat arrhythmias. Airway control can be achieved by means of oropharyngeal airway, endotracheal intubation, and alternative methods (laryngeal mask and cricothyroidotomy). Vascular access can be achieved by the peripheral venous, intraosseous, central venous, and tracheal routes. The most frequent rhythms found in children with cardiorespiratory arrest are nonshockable (asystole, severe bradycardia, pulseless electrical activity, and complete atrioventricular block). In these cases, adrenaline continues to be the essential drug. Currently, low adrenaline doses (0.01 mg/kg IV and 0.1 mg/kg intratracheal administration) are recommended throughout the resuscitation period. Amiodarone (5 mg/kg) is the drug of choice in cases of ventricular fibrillation refractory to electric shock. The treatment sequence for shockable rhythms (ventricular fibrillation and pulseless ventricular tachycardia) is one 4 J/kg electric shock, followed by cardiopulmonary resuscitation (chest compressions and ventilation) for 2 minutes with subsequent reassessment of the electrocardiographic rhythm. Adrenaline must be administered immediately before the third electric shock and subsequently every 3-5 minutes. Amiodarone must be administered immediately before the fourth shock. |
9,092 | Restoring normal sinus rhythm in atrial fibrillation : evidence from pharmacologic therapy and catheter ablation trials. | Although clinical evidence indicates that many of the electrophysiologic and functional changes associated with atrial fibrillation (AF) can be reversed by maintaining normal sinus rhythm (NSR), a series of large-scale randomized trials failed to demonstrate that this strategy provides a survival advantage. These studies have methodologic limitations, however, that restrict their applicability to the entire AF population. Invasive techniques, including percutaneous catheter ablation and the surgical Maze procedure, offer the potential to reduce the frequency of and in some cases cure AF, although there are serious associated risks. The development and refinement of these techniques have improved outcomes, and they now represent a viable early option for select AF patients. In light of its manifest benefits, the restoration and maintenance of NSR through pharmacologic or nonpharmacologic treatment should remain the therapeutic objective for many AF patients. |
9,093 | Study of pathogenesis of ventricular arrhythmia in experimental rats by separation of sinus and ventricular substitutional rhythms. | Pathogenesis of cardiac arrhythmia was determined by EEC changes after ATP-induced complete atrioventricular block. The re-entry mechanism underlays extrasystoles with equal coupling intervals with complexes of ventricular substitution rhythms, which transformed into paroxysmal tachycardia with equal R-R intervals, ventricular flutter, and ventricular fibrillation. Ectopic automaticity was characterized by extrasystole unrelated to the complexes of substitutional rhythms, which was transformed into accelerated idioventricular rhythm and asystole. During trigger activity, the extrasystoles were associated with complexes of basic rhythm and transformed themselves into torsades de pointes and ventricular fibrillation. |
9,094 | Positive troponin-T in noncompaction is associated with neuromuscular disorders and poor outcome. | Though cardiac troponin-T may be positive in hypertrophic and dilated cardiomyopathy, it is not known how often troponin-T is positive in left ventricular hypertrabeculation/ noncompaction (LVHT), an unclassified cardiomyopathy. This retrospective study aimed to assess how often troponin-T is positive in LVHT, is associated with elevated CK, is attributable to cardiac or extra-cardiac causes, in particular neuromuscular disorders (NMDs), or if it is a predictor of poor survival.</AbstractText>Among 100 patients, detected over a period of 11 years, troponin-T was determined at least once in 71 (71%) of them. Troponin-T was determined once in 36 patients, twice in 8 cases, three times in 11 patients, and more than three times in 16 cases. Troponin- T was positive at least once in 12 patients (17%). Forty-five of the 71 patients suffered from a NMD (63%). Troponin-T positivity was associated with elevated CK in 6 cases. Troponin-T-positivity was attributable to acute myocardial ischemia in a single case, to chronic renal failure in 5 cases, to dilated cardiomyopathy in 4 cases, to atrial fibrillation in 3 cases, to heart failure in 4 cases, and to NMD in 10 cases. Troponin-T positivity in LVHT patients with NMD was assumed to be due to cardiac involvement in the disease. Among the 22 patients who died during the observational period troponin was determined in 16 and was positive in 4 (25%).</AbstractText>Troponin-T is positive in 17% of the patients with LVHT. Most of these patients suffer from a NMD. Troponin-T positivity in LVHT predicts the presence of NMD and poor survival.</AbstractText> |
9,095 | Long-term survival after right ventricular infarction. | Right ventricular myocardial infarction (RVMI) is associated with substantial in-hospital and first-year mortality, but few published studies have documented late survival to 5 to 10 years after infarction. We retrospectively identified 69 consecutive patients from Olmsted County, Minnesota, with new RVMI diagnosed between January 1, 1988 and January 1, 1998, in whom coronary angiography was performed soon after admission. Long-term follow-up status was determined for all patients. RVMI secondary to isolated right coronary artery (RCA) disease had a 10-year actuarial survival of 62%, versus 52% for those with combined RCA and left coronary artery (LCA) disease (p = 0.21). Mortality within the first year after infarction was substantial for all patients with RVMI; however, there was a nonsignificant trend for patients with RCA disease (18%) versus those with RCA and LCA disease (27%; p = 0.21). Annual actuarial risks of death beyond the first year to 10 years after infarction were 2% per year for RCA disease and 3% for combined RCA and LCA disease. Patients with combined LCA and RCA disease were older (p = 0.01) but otherwise similar in baseline characteristics to patients with RCA disease. Occurrence of congestive heart failure, atrial fibrillation, and mechanical complications was similar in the 2 groups. In conclusion, RVMI is associated with substantial first-year mortality, which decreases to a much lower attrition rate between years 1 and 10, with no greater long-term mortality in those patients with concomitant LCA disease. |
9,096 | [Natural history of and risk factors for idiopathic atrial fibrillation recurrence (FAP Registry)]. | The natural history of idiopathic atrial fibrillation is not well understood. The aim of this study was to investigate the frequency of and risk factors for disease recurrence.</AbstractText>The study involved 115 patients with a first episode of paroxysmal atrial fibrillation of unknown origin who were included the FAP registry, which contains data from 11 district hospitals in Catalonia, Spain. All patients underwent comprehensive clinical, laboratory, electro-cardiographic and echocardiographic investigations at baseline and were followed up periodically every 6 months to identify the occurrence of new symptomatic episodes and their complications.</AbstractText>During a mean follow-up period of 912 (445) days, 32 (27.8%) patients experienced recurrence of atrial fibrillation. Those who experienced recurrence had a significantly higher left ventricular ejection fraction (P=.023) and smaller end-systolic volume (P<.001), and they were more likely to consume alcohol regularly (P=.013). Cox regression analysis confirmed that these variables had independent prognostic value. In contrast, the occurrence of syncope during the initial episode was associated with a lower likelihood of recurrence (P=.017).</AbstractText>The risk of recurrence of idiopathic atrial fibrillation was high, and was enhanced by moderate alcohol consumption and increased left ventricular activity, probably of sympathetic origin. This trend was less marked in paroxysmal atrial fibrillation of vagal origin.</AbstractText> |
9,097 | Long-term sinus rhythm maintenance after cardioversion of persistent atrial fibrillation: is the treatment's success predictable? | The aim of our study was to identify the clinical and echocardiographic predictors of long-term success of cardioversion in patients with persistent atrial fibrillation (AF). Our study comprised 104 patients (F/M 33/71; mean age 60.4 +/- 7.9 years) assigned to SR restoration and maintenance with sequentially administered antiarrhythmic drugs. Their clinical and transthoracic echocardiographic (TTE) variables were recorded prior to cardioversion and examined for correlation with sinus rhythm (SR) maintenance at 1 year. The variables under consideration included age, gender, echo parameters such as long and short left atrial (LA) axis, LA and right atrial (RA) area, fractional shortening (FS) and left ventricular end-diastolic diameter, AF duration, New York Heart Association functional class, and concomitant diseases. Generalized additive logistic regression method was used to investigate impact of the selected variables on long-term SR maintenance. At 1 year, SR was present in 63.5% of patients. Left atrium area (LA(ar)) > 28 cm (P < 0.02) and FS value >26% (P < 0.05), both measured at baseline, were significantly associated with SR maintenance after 1 year. Patients with large LA(ar) values (>28 cm(2)) presented a significant decrease (31.45 +/- 3.07 cm(2) vs 28.94 +/- 3.81 cm(2); P < 0.008) during 30 days following SR maintenance. In patients with LA(ar) >28 cm(2) we noted an atrial decrease of 2.57 +/- 3.2 cm(2) (P < 0.004) during 30 days following SR restoration, which turned out to be an independent factor related to SR presence at 1 year of follow-up (relative risk 1.83; 95% confidence interval: 1.03-2.95; P < 0.01). Of all the considered variables only LA area and FS value seem to be relatively reliable predictors of SR sustainability at 1 year after an effective cardioversion of persistent AF. |
9,098 | Prevention of new-onset atrial fibrillation and its predictors with angiotensin II-receptor blockers in the treatment of hypertension and heart failure. | Atrial fibrillation is the most frequent occurring sustained cardiac arrhythmia and it is related to common cardiac disease conditions. Hypertension increases the risk of atrial fibrillation by approximately two-fold and, because of the high prevalence of hypertension, it accounts for more cases of atrial fibrillation than any other risk factor. In recent years, there are two large hypertension trials (LIFE and VALUE) and two large heart failure trials (CHARM and Val-HeFT) reporting the beneficial effect of angiotensin II-receptor blockers (ARBs) on new-onset atrial fibrillation, beyond the blood pressure-lowering effect. Blockade of the renin-angiotensin system may prevent left atrial dilatation, atrial fibrosis, dysfunction and conduction velocity slowing. Some studies also indicate direct anti-arrhythmic properties. This review aims to consider the preventive effect of ARBs on new-onset atrial fibrillation observed in recent reports from these trials, and to discuss possible mechanisms of the beneficial effect of angiotensin II-receptor blockade. |
9,099 | Utility of microvolt T-wave alternans to predict sudden cardiac death in patients with cardiomyopathy. | Sudden cardiac death remains a major cause of mortality among patients with cardiomyopathy and implantable cardioverter-defibrillator therapy has been shown to improve survival in these patients. Effective use of prophylactic implantable cardioverter-defibrillator therapy requires accurate risk stratification beyond assessment of ejection fraction, however. Repolarization alternans is a harbinger of ventricular arrhythmias and its measurement from body-surface recordings, also known as microvolt T-wave alternans, is emerging as an effective prognostic tool in these patients based on recent clinical trials.</AbstractText>We review the pathogenesis and determinants of repolarization alternans. The current techniques for measuring T-wave alternans from the body surface are compared, including the spectral and modified moving average methods. Recent clinical trials evaluating the prognostic utility of T-wave alternans in patients with ischemic and nonischemic cardiomyopathy and no prior arrhythmic events are summarized. The findings of these studies are discussed in the context of implantable cardioverter-defibrillator prophylaxis. Body-surface T-wave alternans is an evolving technique and its limitations are presented along with approaches to improve its predictive accuracy.</AbstractText>Risk stratification with T-wave alternans has the potential to guide prophylactic implantable cardioverter-defibrillator therapy in a growing population of patients with cardiomyopathy.</AbstractText> |
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