Lyme carditis: Early occurrence and prolonged recovery.

Lyme carditis is an uncommon manifestation of early disseminated Lyme disease. This case illustrates a 66-year-old male with complaints of fatigue, myalgias, and fever after a tick bite 3days earlier. A large erythema migrans was found on the chest wall. Initial electrocardiogram showed sinus rhythm with second degree 2:1 atrioventricular (AV) block, which progressed to intermittent complete AV block rapidly. He was treated with intravenous ceftriaxone. Over the course of 2-weeks of antibiotic therapy, the intermittent high-grade AV block improved slowly and progressively. This case highlights the importance of timely diagnosis and appropriate management to achieve a favorable prognosis.

A Unique Interplay of Multiple Predisposing Factors Culminating in a Catastrophic QT Prolongation.

Implantable cardioverter-defibrillators (ICDs) are used in patients without a reversible cause for long QT syndrome (LQTS) and secondary prevention in patients with LQTS-associated sudden cardiac arrest. We present a female patient with multiple reversible factors for QT prolongation, including the use of antidepressants, antidiarrheals, antiemetics, and antihistamines; chronic malabsorption from bariatric surgery; probable Gitelman syndrome and urinary losses of electrolytes, causing QT prolongation which leads to polymorphic ventricular tachycardia and a successfully resuscitated cardiac arrest. Our patient also had history suggestive of probable congenital LQTS with multiple childhood syncopal episodes and a history of seizures in first-degree relatives, further justifying the placement of an ICD. Also, this case gives us an opportunity to delve into the risks of catastrophic QT prolongation in the morbidly obese population undergoing bariatric surgery.

Transient Second-Degree Atrioventricular Block: A Rare Finding in Sickle Cell Crisis.

Sickle cell disease (SCD) affects approximately 100,000 Americans, and it occurs in one out of every 365 African American births. Cardiac complications are a common feature of SCD and are an essential cause of the morbidity and mortality associated with SCD. However, there is insufficient literature on SCD and atrioventricular (AV) blocks. We present a case of a young African American male with transient second-degree Mobitz type 1 block during an acute episode of sickle cell crisis.

Malignant neurally-mediated syncope: pathophysiology and treatment.

Neurally-mediated syncope is the most common cause of transient loss of consciousness. In this report, we describe an index case of a 43-year-old man with multiple episodes of neurally-mediated syncope. He underwent tilt-table testing, resulting in asystole for 15 seconds with generalized convulsions. After permanent pacemaker implantation, the patient had another syncopal episode requiring adjustment of pacemaker settings. Current concepts of the pathophysiology as well as the diagnosis and management of this condition are discussed.

Myocardial stunning after electroconvulsive therapy in patients with an apparently normal heart.

Myocardial stunning refers to contractile dysfunction that persists after an ischemic episode and restoration of coronary blood flow. In this article, 2 cases of myocardial stunning after electroconvulsive therapy in patients with an apparently normal heart are presented. The incidence of this condition is unknown. It is observed that this condition seems to occur in females and in the obese and is generally associated with rapid recovery. This occurrence seems to be brought about by autonomic changes that occur during electroconvulsive therapy. Several drugs have been used to ameliorate the condition, although studies were limited to establish efficacy of regimens.

Ventricular geometry-regularized QRSd predicts cardiac resynchronization therapy response: machine learning from crosstalk between electrocardiography and echocardiography.

Up to one-third of patients selected by current guidelines do not respond to cardiac resynchronization therapy (CRT), the aim of this study was to find out novel analytical approaches to improve pre-implantation CRT response prediction. Among 31 pre-implantation features of clinical, laboratory, electrocardiography (ECG), and echocardiography variables in a consecutive cohort of patients receiving a first-time CRT device (CRT-pacemaker or CRT-defibrillator), we developed a machine learning (ML) model with three classification algorithms (support vector machines (SVM), K nearest neighbors, and random subspaces) with the best features combination to predict CRT response. Three categorical variables, left bundle branch block (LBBB), nonischemic cardiomyopathy, and female gender, were independently associated with CRT responses. Among continuous variables, including septal wall thickness, posterior wall thickness, and relative wall thickness (RWT), could regularize ECG QRS duration (QRSd) and significantly enhance the correlation between QRSd and CRT response. The 3 ML algorithms in a total of 38 features combinations constantly recognized that the features combined with QRSd/RWT outperformed the combinations without it. For each of three algorithms, the triplet feature combination of QRSd/RWT, LBBB, and nonischemic cardiomyopathy repeatedly increased the classification rate more than 8%. The best performance for CRT response prediction occurred with SVM model, which proposed actual QRSd/RWT values that favored CRT responses in patients both with and without LBBB. Lower QRSd/RWT values were required for CRT responses in patients with ischemic cardiomyopathy compared to those with non-ischemic cardiomyopathy. ML from ventricular remodeling characteristics-regularized QRSd improves CRT response prediction.

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.

The kidney in heart failure: friend or foe?

Heart failure constitutes a significant source of morbidity and mortality in the United States and its incidence and prevalence continue to grow, increasing its burden on the health care system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This complex interaction is characterized by a pathophysiological disequilibrium between the heart and the kidney, in which cardiac malfunction promotes renal impairment, which in turn feeds back for further deterioration of cardiovascular function. Multiple neurohumoral and hemodynamic mechanisms are involved in this cardiorenal dyshomeostasis, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with cardiorenal dysfunction can be challenging and should be individualized. Emerging therapies must address the impairment of both organs to secure better clinical outcomes. To this end, a multidisciplinary approach is warranted to achieve optimal results.

The cardiorenal syndrome in heart failure: an evolving paradigm.

Heart failure constitutes a significant source of morbidity and mortality in the United States, and its incidence and prevalence continue to grow, increasing its burden on the healthcare system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This interaction, termed the cardiorenal syndrome, is a complex phenomenon characterized by a pathophysiologic disequilibrium between the heart and the kidney, in which malfunction of 1 organ consequently promotes the impairment of the other. Multiple neurohumoral mechanisms are involved in this cardiorenal interaction, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with the cardiorenal syndrome can be challenging and should be individualized. Emerging therapies must address the function of both organs to secure better clinical outcomes. To this end, a multidisciplinary approach is recommended to achieve optimal results.

Left versus right atrial difference in dominant frequency, K(+) channel transcripts, and fibrosis in patients developing atrial fibrillation after cardiac surgery.

BACKGROUND: The development of atrial fibrillation (AF) after cardiac surgery is associated with adverse outcomes; however, the mechanism(s) that trigger and maintain AF in these patients are unknown. OBJECTIVE: The purpose of this study was to test our hypothesis that postoperative AF is maintained by high-frequency sources in the left atrium (LA) resulting from ion channel and structural features that differ from the right atrium (RA). METHODS: Forty-four patients with no previous history of AF who underwent cardiac surgery consented to LA and RA biopsies. Histologic sections evaluated fatty infiltration, fibrosis, and iron deposition; quantitative reverse transcription-polymerase chain reaction (RT-PCR) assessed ion channel expression. In a subset of 27 patients, LA and RA unipolar recording leads were also placed. In patients who developed AF, the dominant frequency (DF) for each lead was calculated using fast Fourier transform. RESULTS: DFs during AF were LA 6.26 +/- 0.8 Hz, RA 4.56 +/- 0.7 Hz (P <.01). RT-PCR revealed LA-to-RA differences in mRNA abundance for Kir2.3 (1.8:1) and Kir3.4 (2.3:1). While LA fibrosis was greater in patients developing AF compared with those remaining in normal sinus rhythm (10.8% +/- 11% vs. 3.8% +/- 3.5%; P = .03), the amount of LA fibrosis inversely correlated with the LA DF. CONCLUSIONS: This is the first demonstration of LA-to-RA frequency differences during postoperative AF, which are associated with LA-to-RA differences in mRNA levels for potassium channel proteins and LA fibrosis. These results strongly suggest that sources of AF after cardiac surgery are located in the LA and are stabilized by LA fibrosis.

El síndrome cardiorenal en insuficiencia cardíaca: un paradigma en evolución / The cardiorenal syndrome in heart failure: an envolving paradigm

Background: Heart failure constitutes a significant source of morbidity and mortality in the United States and its incidence and prevalence continue to grow, increasing its burden on the health care system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This interaction, termed the cardiorenal syndrome, is a complex phenomenon characterized by a pathophysiological disequilibrium between the heart and the kidney, in which malfunction of one organ subsequently promotes the impairment of the other. Multiple neuro-humoral mechanisms are involved in this cardiorenal interaction, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with the cardiorenal syndrome can be challenging and should be individualized. Emerging therapies must address the function of both organs in order to secure better clinical outcomes. To this end, a multidisciplinary approach is recommended to achieve optimal results.

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.

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.

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.