Late onset of exercise induced focal ventricular tachycardia originating from the ventricular end of an A-V accessory pathway after elimination of conduction.

The authors report the unique case of remote onset of exercise induced focal ventricular tachycardia in a 40-year old male patient that originated from the ventricular end of an accessory atrioventricular pathway 18 months after a successful ablation. There was no residual conduction across the pathway after the first ablation. The ventricular tachycardia (VT) was mapped to and successfully ablated at the same site where the ventricular end of the pathway was previously ablated. The VT morphology was similar to that of the pre-excited QRS beats noted before. Thus far, in all reported cases of accessory pathway related automaticity there was intact conduction over the pathway or acute injury to it. To the best of our knowledge a case similar to our patient is not yet reported.

Surface 12 lead electrocardiogram recordings using smart phone technology.

IMPORTANCE: AliveCor ECG is an FDA approved ambulatory cardiac rhythm monitor that records a single channel (lead I) ECG rhythm strip using an iPhone. In the past few years, the use of smartphones and tablets with health related applications has significantly proliferated. OBJECTIVE: In this initial feasibility trial, we attempted to reproduce the 12 lead ECG using the bipolar arrangement of the AliveCor monitor coupled to smart phone technology. METHODS: We used the AliveCor heart monitor coupled with an iPhone cellular phone and the AliveECG application (APP) in 5 individuals. RESULTS: In our 5 individuals, recordings from both a standard 12 lead ECG and the AliveCor generated 12 lead ECG had the same interpretation. CONCLUSIONS: This study demonstrates the feasibility of creating a 12 lead ECG with a smart phone. The validity of the recordings would seem to suggest that this technology could become an important useful tool for clinical use. This new hand held smart phone 12 lead ECG recorder needs further development and validation.

Tricuspid valve incompetence following implantation of ventricular leads.

Most cardiovascular implantable electronic devices (CIEDs) require a ventricular lead to be placed across the tricuspid valve. Tricuspid regurgitation (TR) is an understudied clinical complication of right ventricular lead implantation and its clinical significance is unknown. We review the incidence, predictors, and current management of TR as a complication of ventricular lead implantation. Emerging technologies, including leadless pacing devices and subcutaneous systems, offer the benefit of little or none tricuspid valve disruption.

An atypical case of vagally mediated atrial fibrillation in an elderly woman: electrocardiographic caveats to diagnosis.

Vagally mediated paroxysmal atrial fibrillation is typically described to occur in otherwise healthy young-to-middle aged males during periods of high vagal tone. We report a case of cardioinhibitory type neurocardiogenic syncope associated with atrial fibrillation in an elderly female during episodes of nausea. This was replicated during tilt-table testing. The atrial fibrillation was part of a unique snap shot of the entire electrophysiological spectrum of the vagal response captured in detail in this index patient.

Old and new antiarrhythmic drugs for converting and maintaining sinus rhythm in atrial fibrillation: comparative efficacy and results of trials.

In managing atrial fibrillation (AF), the main therapeutic strategies include rate control, termination of the arrhythmia, and the prevention of recurrences and thromboembolic events. Safety and efficacy considerations are important in optimizing the choice of an antiarrhythmic drug for the treatment of AF. Recently approved antiarrhythmics, such as dofetilide, and promising investigational drugs, such as azimilide and dronedarone, may change the treatment landscape for AF. For medical conversion of recent-onset AF, class IC antiarrhythmic drugs, administered as an oral bolus, have been demonstrated to be the most efficacious pharmacologic conversion agents. Intravenous ibutilide and oral dofetilide both have efficacies superior to placebo in controlled trials for converting persistent AF. Comparative trials in paroxysmal AF have demonstrated that flecainide, propafenone, quinidine, and sotalol are equally effective in preventing recurrences of AF. Amiodarone has been demonstrated to be more efficacious than propafenone or sotalol in the Canadian Trial of Atrial Fibrillation. In persistent AF, twice-daily dofetilide has been shown to be as or more effective than low-dose sotalol given twice daily for the maintenance of sinus rhythm in patients with AF. Trials have demonstrated that subjective adverse effects are less frequent with class IC drugs, sotalol, and dofetilide compared with such drugs as quinidine. In patients without structural heart disease, flecainide, propafenone, and D,L-sotalol are the initial drugs of choice, given their reasonable efficacy, low incidence of subjective side effects, and lack of significant end-organ toxicity. Treating AF in patients with left ventricular dysfunction can be difficult because of associated electrophysiologic derangements, potential proarrhythmic concerns, and negative inotropic effects of antiarrhythmics. Some data exist suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can prevent AF either by preventing atrial dilation and stretch-induced arrhythmias or by blocking the renin-angiotensin system. In post-myocardial infarction patients, D,L-sotalol, dofetilide, and amiodarone-and in congestive heart failure patients, amiodarone and dofetilide-have demonstrated neutral effects on survival in controlled trials. In the Congestive Heart Failure Survival Trial of Antiarrhythmic Therapy (CHF-STAT), amiodarone lowered the frequency of AF development and improved left ventricular ejection fraction over time. In CHF-STAT, there was lower mortality in patients who converted from AF to sinus rhythm. Dofetilide decreased rehospitalization for congestive heart failure in the Danish Investigations of Arrhythmia and Mortality on Dofetilide (DIAMOND) trials. Neutral effects on survival and favorable hemodynamics have positioned amiodarone and dofetilide as the antiarrhythmics of choice in patients with left ventricular dysfunction. In post-myocardial infarction patients, sotalol is an additional agent to consider for treatment of AF in this setting.

A review of clinical trials assessing the efficacy and safety of newer antiarrhythmic drugs in atrial fibrillation.

Clinical trials assessing the efficacy of anti- arrhythmic drugs for terminating atrial fibrillation have demonstrated that rate control drugs have little to no added efficacy compared to placebo; however, spontaneous conversion of recent-onset atrial fibrillation is common. Antiarrhythmic drugs such as oral dofetilide, oral bolus-flecainide and propafenone and intravenous ibutilide all have a role in terminating atrial fibrillation. Active comparator trials have demonstrated that amiodarone is more efficacious in maintaining sinus rhythm than propafenone and sotalol. Multiple trials have demonstrated the safety of amiodarone, sotalol, dofetilide and azimilide in a post-myocardial infarction population and amiodarone and dofetilide in a congestive heart failure population. Newer antiarrhythmic agents, some with novel mechanisms of action, will add to the pharmacologic armamentarium in treating atrial fibrillation.

Entrainment of ventricular tachycardia with a permanent biventricular pacemaker.

Biventricular pacing has been introduced as a treatment for congestive heart failure. These devices presently pace and sense from two disparate ventricular sites. Antitachycardia pacing (ATP) is used for termination of sustained monomorphic ventricular tachycardia (VT) and has been incorporated with simultaneous dual site ventricular pacing for treatment of VT. We report a case of entrainment of sustained monomorphic VT in a 62-year-old female with an ischemic cardiomyopathy and VT, who received a biventricular pacemaker-implantable cardioverter defibrillator, Contak CD (Guidant, St. Paul, MN). Biventricular pacing sites were at the right ventricular apex and the middle of the anterior cardiac vein on the left ventricle. The entrained VT has a left bundle branch block and left axis deviation morphology with a cycle length of 350 msec. ATP at 270 msec produced concealed entrainment of an induced VT. Only one pacing site demonstrated capture. The inability to capture both pacing sites simultaneously was the result of ventricular refractoriness at one of the sites during ATP of the VT. The entrance and exit points of the loop for VT appeared to rest between the two pacing sites in the intraventricular septum. This case illustrates one of the sensing limitations of today's biventricular pacing defibrillator systems.

Clinical significance of increased tricuspid valve incompetence following implantation of ventricular leads.

PURPOSE: Cardiac rhythm management devices (CRMD) require a ventricular lead to be placed across the tricuspid valve. Tricuspid regurgitation (TR) is an under-recognized clinical complication of lead implantation and its clinical significance is unknown. We studied the incidence of hospitalizations for congestive heart failure (CHF) exacerbation among patients with worsening TR after ventricular lead implantation. METHODS: We reviewed 148 patients (age 68 ± 15) that received a CRMD. TR and pulmonary artery systolic pressure (PASP) measured by Doppler echocardiography before and after CRMD implantation were analyzed. Hospitalizations for CHF exacerbation post-implantation were counted. RESULTS: Follow-up was 32 ± 14 months. Ninety-nine (67%) patients had no change, 24 (16%) slight, and 9 (6%) significant increase in TR after CRMD implantation, while 13 (9%) patients had slight and 3 (2%) significant improvement. Patients with a significant increase in TR had higher incidence of hospitalizations (1.7 ± 0.5) compared to patients with slight (0.8 ± 1; p = 0.006) or no increase (0.5 ± 1; p = 0.0002) in TR. Patients with significant increase in TR had a greater change in PASP (25 mmHg; p = 0.002) after device implantation compared to those with a slight (10 mmHg; p = 0.002) or no increase (0.7 mmHg; p = 0.17). CONCLUSION: Increased TR following CRMD implantation is relatively common (33%) and correlated with subsequent risk of hospitalization for heart failure. A preventive strategy and close monitoring for development or worsening of CHF after CRMD implantation may help prevent hospital admissions.

A review of the pharmacokinetics, electrophysiology and clinical efficacy of dronedarone.

The results of major clinical trials and advances in pharmacologic and nonpharmacologic therapies are continuing to alter treatment approaches for both atrial and ventricular arrhythmias. Originally developed as an antianginal medication, amiodarone serves as the most effective antiarrhythmic drug in the treatment of both atrial and life-threatening ventricular arrhythmias. However, amiodarone has complex pharmacokinetics and is associated with serious extracardiac side effects, partially due to the presence of an iodine moiety. With a better understanding of the mechanisms of arrhythmias and antiarrhythmic drugs, new antiarrhythmic agents are currently under development with the hope that they will be more effective and safer than currently available drugs. One such drug that might potentially fulfill this hope is dronedarone. This amiodarone-like compound lacks the iodine moiety, and is similar in structure and electrophysiologic mechanisms of action to amiodarone, to date no evidence of liver, thyroid or pulmonary toxicity has been reported. Three clinical trials demonstrate efficacy in suppressing recurrences of atrial fibrillation and there is also evidence of a rate-slowing benefit during atrial fibrillation/flutter. However, the ANtiarrhythmic trial with DROnedarone in Moderate-to-severe congestive heart failure Evaluating morbidity Decrease (ANDROMEDA) study, performed in patients with left ventricular dysfunction, demonstrated excess noncardiac mortality in patients treated with dronedarone. Although effective in the treatment of atrial fibrillation, the future of this novel amiodarone-like drug remains uncertain until further clarification of the excess mortality in heart failure patients is better studied.

Selection of drugs in pursuit of rate control strategy.

Atrial fibrillation is the most common sustained arrhythmia. Based on multiple large randomized trials, rate control therapy has been shown to be safe and effective and is gaining greater acceptance as a frontline alternative to drugs to maintain sinus rhythm. Adequate rate control can be achieved by atrioventricular nodal blocking agents both in the acute and chronic settings. In refractory patients, other methods such as atrioventricular node ablation can be used to control rate.

The Brugada syndrome.

The Brugada syndrome describes a subgroup of patients at risk for the occurrence of ventricular fibrillation who have no definable structural heart disease associated with a right bundle branch block conduction pattern and ST-segment elevation in the right precordial leads. This syndrome is caused by genetic defects in the alpha subunit of the sodium channel. This defect causes a reduction in the sodium channel current, which accentuates the epicardial action potential notch leading to ST-segment elevation. Sodium channel blockers can potentiate these findings and screen for patients with intermittent baseline electrocardiographic findings. Because of the poor prognosis of such patients, symptomatic patients should be treated with an implantable cardioverter-defibrillator.

Maintaining stability of sinus rhythm in atrial fibrillation: antiarrhythmic drugs versus ablation.

In managing atrial fibrillation, the main therapeutic strategies include rate control, termination of the arrhythmia, and pr vention of recurrences and thromboembolic events. Rate control with digoxin, b-blockers, verapamil, and diltiazem may be preferred in drug refractory and sedentary patients with markedly dilated left atrium and atrial fibrillation of long duration. Drugs useful in the maintenance of sinus rhythm include quinidine, procainamide, disopyramide, sotalol, amiodarone, dofetilide, flecainide, and propafenone. In patients with structural heart disease, the class III antiarrhythmics are the initial drugs of choice, given their neutral effects on survival in a post-myocardial infarction and congestive heart failure population. Due to high recurrence rates with pharmacologic therapy, nonpharmacologic options of therapy include atrioventricular junction ablation, atrial defibrillators, catheter ablation of pulmonary vein foci, and attempts to perform an atrial Maze procedure using catheters. Hybrid therapy using drugs in combination with nonpharmacologic approaches will be used more frequently in the future for refractory patients.

Arrhythmias in Patients with Heart Failure.

Both atrial and ventricular arrhythmias are very common in patients with congestive heart failure, and their presence is associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial and ventricular arrhythmias in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. The presence of ventricular arrhythmias in patients with ischemic cardiomyopathy identifies patients at high risk for sudden death. However, in patients with nonischemic cardiomyopathy there is not a strong correlation between ventricular arrhythmias and increased risk for sudden death. Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients 1) post-myocardial infarction; 2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and 3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac arrest. The purpose of this article is to present an overview of arrhythmias in patients with heart failure and discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the current therapies presently used.

Complications of biventricular pacing.

PURPOSE OF REVIEW: Cardiac resynchronization therapy, a biventricular pacemaker-based therapy for heart failure, is increasingly being used based on a variety of clinical studies. However, the complications and risks related to different aspects of this novel therapy are not well documented. This review summarizes the data derived from major clinical trials about the complications related to implantation, hardware, and programming of biventricular devices. RECENT FINDINGS: Several clinical trials have reported the complications related to biventricular device implantation. However, there are no reports available providing a comprehensive review on all the possible complications related to cardiac resynchronization devices. SUMMARY: With a clear understanding of the potential complications and meticulous approach to implant and programming, the incidence of complications can be minimized.

Biventricular pacing in congestive heart failure: a boost toward finer living.

With 550,000 new cases each year, congestive heart failure is a major medical problem. Several medical therapies, including digoxin, angiotensin-converting enzyme inhibitors, and beta-blockers, have reduced the number of re-hospitalizations and slowed the progression of congestive heart failure. Angiotensin-converting enzyme inhibitors, some beta-blockers, and the combination of hydralazine with nitrates have improved survival. Despite these benefits, medical therapy frequently fails to improve quality of life. Biventricular pacing has been introduced to resynchronize mechanical and electrical asynchrony frequently observed in patients with heart failure. The most recent pacing trials show an improvement in quality of life and functional class. Long-term data are needed to determine the effect of biventricular pacing on survival. The acute hemodynamic studies suggest that resynchronization pacing therapy may predict a positive long-term benefit for many patients with congestive heart failure.

Atrial fibrillation in patients with heart failure.

Atrial fibrillation and heart failure are very common cardiac disorders, and both are associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial fibrillation in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. Multiple trials using either pharmacologic or nonpharmacologic therapies in an attempt to manage atrial fibrillation have been developed. The purposes of this review are to present an overview of atrial fibrillation in patients with heart failure and to discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the therapies presently used.

Atrial fibrillation in heart failure: prognostic significance and management.

AF in Heart Failure. Atrial fibrillation and congestive heart failure are commonly occurring cardiac disorders that often exist concomitantly. The prognostic significance of the presence or absence of atrial fibrillation, as an independent risk factor, in patients with heart failure remains controversial. Antiarrhythmic drugs with good hemodynamic profiles and neutral effects on survival are preferred treatments for converting atrial fibrillation and maintaining sinus rhythm. Other standard therapies for congestive heart failure, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and beta-blockers also have a role in the treatment of these coexisting disease states. The article presents an overview of atrial fibrillation in patients with heart failure and reviews the prevalence, prognostic significance, and efficacy of various antiarrhythmic agents for the conversion and maintenance of sinus rhythm.