Atrial arrhythmias following ostial or circumferential pulmonary vein ablation.

Aims: The incidence, clinical significance and optimum treatment of AF ablation-induced proarrhythmia is not entirely known. This report describes the incidence and management of atrial arrhythmias occurring after various techniques for the ablative therapy of atrial fibrillation (AF).

Methods: Five hundred and forty-four patients with paroxysmal atrial fibrillation were subjected to ostial pulmonary vein (PV) (n = 204), antral (n = 300), or circumferential (n = 40) ablation around the PV ostia.

The Managed Ventricular pacing versus VVI 40 Pacing (MVP) Trial: clinical background, rationale, design, and implementation.

Background: Implantable cardioverter defibrillators (ICDs) reduce mortality among appropriately selected patients who have had or are at risk for life-threatening ventricular arrhythmia. Right ventricular apical (RVA) pacing has been implicated in worsening heart failure and death. The optimal pacemaker mode for bradycardia support while minimizing unnecessary and potentially harmful RVA pacing has not been determined.

Percutaneous intrapericardial echocardiography during catheter ablation: a feasibility study.

Background: Percutaneous pericardial access, epicardial mapping, and ablation have been used successfully for catheter ablation procedures.

Objectives: The purpose of this study was to evaluate the safety and feasibility of closed-chest direct epicardial ultrasound imaging for aiding cardiac catheter ablation procedures.

Methods: An intracardiac ultrasound catheter was used for closed-chest epicardial imaging of the heart in 10 patients undergoing percutaneous epicardial access for catheter ablation.

Atrioventricular junction ablation followed by resynchronization therapy in patients with congestive heart failure and atrial fibrillation (AVERT-AF) study design.

Atrial fibrillation (AF) and congestive heart failure (CHF) affect millions of patients in the United States. Several studies suggest that AF and in particular the irregular ventricular response might be contributing to the left ventricular dysfunction. Studies that compared pharmacologic rate control to atrioventricular junction (AVJ) ablation followed by right ventricular pacing which restores a regular ventricular response, failed to show an improvement when compared to pharmacological rare control.

Incidence, time course, and characteristics of microbubble formation during radiofrequency ablation of pulmonary veins with an 8-mm ablation catheter.

Background: Microbubble formation during pulmonary vein (PV) radiofrequency (RF) ablation of atrial fibrillation (AF) occurs relatively frequently. Prior studies have shown that microbubble formation may be associated with an increased risk of complications. However, the incidence, time course, and temperature characteristics of microbubble formation during AF ablation with an 8-mm catheter have not been prospectively described in humans.

Atrial activation during atrioventricular nodal reentrant tachycardia: studies on retrograde fast pathway conduction.

Background: Detailed right and left septal mapping of retrograde atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) has not been undertaken and may provide insight into the complex physiology of AVNRT, especially the anatomic localization of the fast and slow pathways.

Objectives: The purpose of this study was to investigate the pattern of retrograde atrial activation during typical AVNRT by means of right-sided and left-sided septal mapping and implementation of pacing maneuvers for separating atrial and ventricular electrograms recorded during tachycardia.

Methods: Twenty-two patients with slow-fast AVNRT were studied by means of simultaneous His-bundle recordings from the right and left sides of the septum.

Focus on management of pacemaker and ICD advisories, recalls, and alerts.

Because the number of implantable cardiac devices has dramatically increased, device alerts and advisories have become a part of routine clinical practice. When a physician is faced with the management of a patient with an implanted device that has been the subject of a recall or advisory, the major concern facing the clinician is how to manage the patient and whether the device needs to be replaced. A rational approach to evaluating patients with a device or lead that is the subject of a US Food and Drug Administration advisory requires evaluating the competing risks of elective device or lead replacement versus keeping the recalled device or lead in place.

Paradoxical undersensing during atrial flutter: what is the mechanism?

A patient with congenital complete heart block underwent implantation of a dual-chamber pacemaker. He presented to the emergency room with fatigue and was found to be in atrial flutter. Device interrogation revealed undersensing of 5 mV flutter waves at a programmed sensitivity of 0.

Management of recalled pacemakers and implantable cardioverter-defibrillators: a decision analysis model.

Context: Limited information exists to direct clinical management after an implantable device has been put under advisory. A better understanding of the risks and benefits of device replacement compared with continued clinical follow-up would be helpful to clinicians.

Objective: Using the tools of decision analysis, to determine the best management approach (immediate device replacement vs continued monitoring) in the setting of a device advisory.

Cardiovascular outcomes with atrial-based pacing compared with ventricular pacing: meta-analysis of randomized trials, using individual patient data.

Background: Several randomized trials have compared atrial-based (dual-chamber or atrial) pacing with ventricular pacing in patients with bradycardia. No trial has shown a mortality reduction, and only 1 small trial suggested a reduction in stroke. The goal of this review was to determine whether atrial-based pacing prevents major cardiovascular events.

Defibrillation energy requirements in an ICD population receiving cardiac resynchronization therapy.

Objectives: While defibrillation energy requirements (DERs) have been extensively studied in patients receiving conventional defibrillators, the DERs of patients receiving cardiac resynchronization therapy with defibrillation capability (CRT-D) devices have not been well described. The purpose of this analysis was to characterize DERs (defined as true threshold or the presence of appropriate safety margins) in patients undergoing implant of a CRT-D and to determine whether DERs in this population were similar to those reported for patients undergoing implantation of conventional defibrillators.

Methods: Data were analyzed retrospectively from the VENTAK CHF/CONTAK CD biventricular pacing study.

Detection of microbubble formation during radiofrequency ablation using phonocardiography.

Aims: To detect and characterize the acoustic energy generated by microbubble (MB) formation in an isolated tissue preparation. MB formation during radiofrequency (RF) ablation indicates excessive tissue heating and may precede explosive 'pops'. Currently, MB formation can only be detected with echocardiography.

Is time to first recurrence of atrial fibrillation correlated with atrial fibrillation burden?

The time to the first recurrence of atrial fibrillation (AF) and the AF burden have commonly been used as end points for AF therapy. We conducted a retrospective analysis of data from a large pacemaker registry to assess the relation between the time to the first recurrence and the AF burden. Although a statistical association exists, the small correlation coefficients limit the clinical value of the time to first recurrence as an indicator of AF burden.

Cardiac pacing in the elderly.

Sinus node disease and atrioventricular block are common etiologies of symptomatic bradyarrhythmias in the elderly and remain the leading indications for permanent pacemaker implantation. In fact, the vast majority (>80%) of all pacemakers are implanted in the elderly. Whereas indications of pacemaker therapy have been largely unchanged over the past several years, several questions, such as differences in pacemaker mode selection, remained unanswered.

Effect of slow pathway ablation in atrioventricular nodal reentrant tachycardia on the electrophysiologic characteristics of the inferior atrial inputs to the human atrioventricular node.

The inferior atrial extensions of the atrioventricular (AV) node have been related to the anatomic substrate of the slow pathway, but their role in AV nodal reentrant tachycardia (AVNRT) is unknown. Ten patients with slow-fast AVNRT were studied before and after successful slow pathway ablation. Simultaneous His bundle recordings from the right and left sides of the septum were made during right and left inferoparaseptal pacing.