Left ventricular-based pacing is an established method for treatment of congestive heart failure in patients with ventricular dyssynchrony. The transvenous epicardial approach is the method of choice to pace the left ventricle. AIMS: To evaluate short and long-term stability and pacing and sensing performance of an S-shaped non-steroid unipolar lead. ...

BACKGROUND: Echocardiography is increasingly used for noninvasive evaluation of cardiac function and morphology in small animal models of cardiovascular diseases. The aims of this study were to develop a simple method for stress echocardiography in rats and to evaluate left ventricular function of the postinfarct remodeling heart during stress induced ...

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 (CHF) improving survival. Despite these benefits, medical therapy frequently fails to improve quality of life. Since 1990, there has been a growing interest in using cardiac ...

We report a case of left accessory atrioventricular pathway (AP) which antegrade conduction was manifest during pacing from the anterior site of the atrial insertion, but absent during pacing from the posterior site. Infusion of adenosine triphosphate during pacing from the posterior site induced a conduction block of atrioventricular node ...

Zebrafish and Xenopus have become popular model organisms for studying vertebrate development of many organ systems, including the heart. However, it is not clear whether the single ventricular hearts of these species possess any equivalent of the specialized ventricular conduction system found in higher vertebrates. Isolated hearts of adult zebrafish ...

A 74-year-old patient was referred for a rapidly increasing pacing threshold 9 months after DDD pacemaker implantation because of symptomatic total atrioventricular (AV) block. She had a history of hypertension, diabetes with micro-angiopathy and a recent transient ischaemic attack. The paced electrocardiogram on admission had a right bundle branch block ...

Biventricular pacing is emerging as a long-term therapy for symptomatic heart failure. Analysis of heart rate variability (HRV) has become an important predictive tool in this syndrome. To assess whether chronic resynchronization therapy can affect HRV in patients with heart failure. Thirteen patients with heart failure were studied (mean age+/-1 ...

OBJECTIVE: Patients with heart failure may have conduction abnormalities in up to 30%, further aggravating cardiac output. Drugs worsen these abnormalities and resynchronisation therapy with biventricular pacing improves cardiac function by effecting a more coordinated and efficient ventricular contraction. We report here the technique of biventricular pacing and its results. ...

A 71-year-old woman had undergone valvular heart surgery in 1981, and implantation of a permanent ventricular pacemaker for ventricular pauses during atrial fibrillation in 2001. One year after pacemaker implantation, she complained of faintness. When pacing at 100 beats/min the pacemaker functioned properly. However, pacing and sensing failure was detected ...

We have shown recently that selegiline exerts a cardiac neuroprotective effect in chronic heart failure. Since selegiline has an antioxidant antiapoptotic effect, we proposed to determine whether selegiline attenuates cardiac oxidative stress and myocyte apoptosis in chronic heart failure by modulating Bcl-2 and Bax protein expression, and whether the effects ...

The matrix metalloproteinases (MMPs) are an endogenous family of proteolytic enzymes implicated to contribute to LV remodeling. However, broad-spectrum MMP inhibition (MMPi), particularly inhibition of interstitial collagenase (MMP-1), may not be clinically applicable. This study examined the effects of selective MMPi (sparing MMP-1) in a model of developing congestive heart ...

Management of acute myocardial ischaemia is dependent upon interpretation of the 12-lead electrocardiogram. The presence of ventricular pacing and acute myocardial infarction makes electrocardiogram interpretation difficult. This may impact upon patient management if treating staff are unaware of the expected electrocardiogram morphology or do not have a rapidly available means ...

Biventricular pacing in association with a persistent left-sided superior vena cava is technically challenging. The presence of an associated innominate vein enables a conventional approach via the right atrium for coronary sinus intubation and left ventricular lead placement. In its absence, the coronary sinus lead must be positioned exclusively via ...

Junctional ectopic tachycardia (JET) is a life-threatening arrhythmia frequently seen after surgical correction of congenital heart defects. This study evaluates the use of a modified, commercially available temporary dual chamber pacemaker used to reestablish AV synchrony by R wave synchronized atrial pacing, a technique not routinely applied because of a ...

INTRODUCTION: Recent studies have reported the use of temporary epicardial atrial pacing as prophylaxis for postoperative atrial fibrillation (AF). The aim of this study was to assess the effect of pacing therapies for prevention of postoperative AF using meta-analysis. METHODS AND RESULTS: Using a computerized MEDLINE search, eight pacing prophylaxis ...

Biventricular pacing has been suggested as offering greater hemodynamic benefit than single site pacing in patients with advanced heart failure and left bundle branch block. This was tested using acute multisite pacing. Eighteen such patients were atrialsensed, ventricular multisite paced in random order for 5 minutes. The best achieved measure ...

We hypothesized that decreases in expression and/or activity of cAMP-specific phosphodiesterases (PDE) contribute to protective adaptations observed in lung after heart failure. In this study, we compared PDE activity in lung parenchyma isolated from control dogs and those paced to heart failure by assaying cyclic nucleotide hydrolysis in fractions of ...

It has been shown in animals and humans that AF shortens the atrial refractory period and impairs its rate adaptation. The aim of the study was to evaluate the effects of high rate pacing on sinus node function and intraatrial conduction. Eight dogs were subjected to rapid atrial pacing (AP) ...

Persistence of left superior vena cava (LSVC) is an uncommon finding during pacemaker implantation, which may be particularly relevant in performing LV transvenous pacing. Rarely, it is further complicated by the presence of atresia of the coronary sinus ostium (CSO). This article reports the authors experience with biventricular pacing (Biv-P) ...

Although it has been suggested that multisite ventricular pacing alleviates heart failure by restoring ventricular electrical synchronization, the respective roles of voltage output, interventricular delay, and pacing sites in the development of ventricular arrhythmias occurrence have not been studied during biventricular pacing or LV pacing. Voltage-sensitive dye was used in ...

BACKGROUND: Biventricular pacing (resynchronization therapy) improves the duration and quality of life in a subset of patients with congestive heart failure, but this technique has received little attention in the cardiac surgery literature. This report presents some preliminary ideas about its rationale and technique, and some likely indications for this ...

The effects of different pacing protocols on left ventricular (LV) torsion were evaluated over the full cardiac cycle. A systolic and diastolic series of magnetic resonance imaging (MRI) scans were combined and used to calculate the torsion of the LV in a canine model. The asynchronous activation resulting from ventricular ...

Cardiac glycoside toxicity is frequently associated with hyperkalemia and dysrhythmias in patients with renal insufficiency. Two common therapeutic options for these complications (calcium and transvenous cardiac pacing) are considered contraindicated in the setting of cardiac glycoside toxicity. We present the case of a patient presenting with a pronounced bradydysrhythmia and ...

Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross-sectional images are ...

Recently, multisite atrial pacing has been suggested as an alternative therapy to prevent recurrences of paroxysmal atrial fibrillation (PAF). A study was conducted to compare the acute effects of biatrial (BiA), left atrial (LA), and right atrial appendage (RAA) pacing on cardiac hemodynamics. In 14 patients with PAF and a ...

Current pacing practice is undergoing continuous and substantial changes. Initially pacing had an exclusively palliative role, since it was reserved for patients developing complete heart block or severe symptomatic bradycardia. With the appearance of novel pacing indications such as pacing for heart failure and atrial fibrillation, the effect of pacing ...

Biventricular pacing via a branch vein of the coronary sinus is not always possible due to anatomical reasons including phrenic nerve stimulation, scarred myocardium unable to sense or pace, and distorted anatomy prohibiting entry into the coronary sinus. Three patients are described in which alternative site pacing with an electrode ...

A 72-year-old woman who was experiencing incessant ventricular tachycardia and recurrent automatic implantable cardioverter defibrillator (AICD) firing despite amiodarone therapy was referred to the Cleveland Clinic Foundation. Myocardial ischemia and infarction were ruled out by standard means. Several antiarrhythmic medications were tried previously without success. Moricizine, 200 mg three times ...

Resynchronization with biventricular pacing is a relatively new and important nonpharmacological therapy for patients with heart failure. A prolonged PR interval, a wide QRS, and left bundle branch block are typical conduction disturbances associated with left ventricular dysfunction. The intraventricular conduction delays often lead to loss of synchronization of ventricular ...

It is known that an electrocardiogram (ECG) after transvenous right ventricular (RV) pacing should yield left bundle branch block (LBBB) QRS patterns. When right bundle branch block (RBBB) pacing morphology appears in a patient with a permanent or temporary transvenous RV pacemaker, myocardial perforation or malposition of the pacing lead ...

Left ventricular (LV) pacing is increasingly used in the management of congestive heart failure. Optimization of the atrioventricular (AV) interval is essential to maximize the hemodynamic benefits of this therapy. Although Doppler echocardiography (echo) is the most widely used method, it is time-consuming, expensive, and operator-dependent. We examined the value ...

Closed-loop stimulation (CLS) is a physiological system for adaptive rate pacing based on monitoring and processing of the intracardiac impedance. The "standard" CLS algorithm (SCLS) requires continuous ventricular pacing. A new, enhanced CLS algorithm (ECLS) provides rate modulation during sensed and paced ventricular depolarizations. The aim of this study was ...

This study examines the effects of various atrial lead positions in physiological pacing on the incidence of AF in patients with sick sinus syndrome. The lead is implanted in the RA free wall, in the RA appendage, near the coronary sinus ostium (CSO) or, in dual site RA pacing, in ...

Data from the completed "Suppression of Atrial Fibrillation by DDD+ Overdrive Pacing with Inos2 CLS (closed-loop system) Pacemakers" multicenter trial were retrospectively evaluated to examine the influence of concomitant antiarrhythmic drugs on the clinical success of conventional single site right atrial overdrive pacing compared with DDD pacing. The DDD+ overdrive ...

This study presents a patient with idiopathic dilated cardiomyopathy who had suffered from multiple ICD shocks. Amiodarone and a beta-blocker failed to suppress ventricular tachycardia. His ECG showed a very wide QRS complex with an intraventricular conduction delay, so biventricular (BV) pacing was attempted. The BV pacing successfully prevented the ...

CONTEXT: Implantable cardioverter defibrillator (ICD) therapy with backup ventricular pacing increases survival in patients with life-threatening ventricular arrhythmias. Most currently implanted ICD devices provide dual-chamber pacing therapy. The most common comorbid cause for mortality in this population is congestive heart failure. OBJECTIVE: To determine the efficacy of dual-chamber pacing compared ...

INTRODUCTION: Pacing is believed to prevent atrial fibrillation by reducing atrial activation time. Exact correlation between P wave duration (PWD) on surface ECG and endocardial atrial activation time is still unexplored. METHODS AND RESULTS: In 15 patients without structural heart disease (9 women, age 45 +/- 14 years), single site ...

Complete atrioventricular (AV) block in hydrops fetalis is associated with high mortality. Fetal ventricular pacing to restore ventricular rate can be an effective procedure, however, no fetal data has shown an appropriate epicardial ventricular pacing site. To evaluate the hemodynamic effect of right and left ventricular pacing in fetal lambs ...

Biventricular pacing for the treatment of congestive heart failure has consistently demonstrated improvement in quality-of-life and reduction in heart failure symptoms. Though the over-the-wire systems will be helpful in overcoming many existing obstacles to optimal lead placement, anatomic variability will still limit overall success. Cardiac vein angioplasty may be required ...

BACKGROUND: Dual chamber pacemakers (single chamber pacing dual chamber sensing cardiac pacemaker (VDD) and dual chamber pacing and sensing cardiac pacemaker (DDD)) are being used frequently in children and adolescents. The aim of this study was to verify the safety and performance of the VDD and DDD pacing systems, and ...

BACKGROUND: Biventricular pacing induces well-known effects on myocardial wall function, apparently providing better results in comparison with conventional right pacing in patients presenting with dilated cardiomyopathy (DCM). However, at the moment the secondary changes in myocardial metabolism induced by pacing devices are unclear. The aim of our study was to ...

Pacemakers are commonly implanted by veterinary cardiologists in dogs with bradyarrhythmias. In the past, these pacemakers were placed with little attention to programming except for the basic heart rate. However, the availability of pacing programmers has permitted a better appreciation of the needs for proper and safe pacing in dogs. ...

The authors utilized rapid right atrial pacing and handgrip exercise to provoke myocardial ischemia in 20 participants (age >65 years) who, for reasons of disability, were not candidates for exercise and pharmacologic stress testing. Echocardiographic left ventricular ejection fraction and left ventricular wall motions were obtained during pacing at baseline ...

The induction of complete heart block by radiofrequency ablation of the atrioventricular junction combined with pacemaker implantation has become an established therapy for rate control in patients with atrial fibrillation who are unresponsive to drugs. Reports of ventricular arrhythmias and sudden death after ablation have, however, raised concerns about safety. ...

OBJECTIVES: We sought to evaluate the long-term effects of alternative right ventricular pacing sites on myocardial function and perfusion. BACKGROUND: Previous studies have demonstrated that asynchronous ventricular activation due to right ventricular apical (RVA) pacing alters regional myocardial perfusion and functions. METHODS: We randomized 24 patients with complete atrioventricular block ...

This case report describes a patient with biventricular pacemaker in whom a far-field sensing of left atrial activity by the pacemaker's ventricular channel resulted in ventricular pacing inhibition. Placing of the left ventricular pacing electrode in the proximal part of the coronary sinus tributary resulted in this far-field sensing problem, ...

AIMS: To prove the feasibility and safety of left interventricular septal pacing. BACKGROUND: Right ventricular apical pacing is an established but haemodynamically less favourable pacing method compared with transvenous left ventricular pacing. Alternatively, we propose a simple septal screw-in lead for left interventricular septal pacing. METHODS: A pacemaker lead with ...

The phenomenon of anodal-break excitation during end-diastolic stimulation of the heart was discovered many years ago by B. Hoffman. Yet, the existence and mechanistic explanation of this effect remain controversial. We sought to confirm its existence and to determine a possible role of half-cell potential. We used isolated Langendorff-perfused rabbit ...

Cardiac resynchronization therapy for the treatment of medically refractory heart failure requires coronary sinus lead placement for left ventricular pacing. Coronary sinus lead placement is technically difficult with success rates reported between 53% to 98% and implantation times ranging from 90 minutes to 5 hours. We report the use of ...

AIMS: To show reversed remodelling of the left ventricle and left atrium after upgrading to biventricular pacing in a patient with worsening heart failure due to VVIR pacing. To review the literature concerning reversed remodelling after upgrading to biventricular pacing. METHODS AND RESULTS: In a 61-year-old man, with cardiomyopathy and ...