Extravascular Implantable Cardioverter-Defibrillator Sensing and Detection in a Large Global Population.

Background: The extravascular (EV) implantable cardioverter-defibrillator (ICD) includes features to address sensing and arrhythmia detection challenges presented by its substernal lead location.

Objectives: In this study, the authors sought to evaluate sensing and detection performance in 299 patients discharged with an EV-ICD in the global pivotal study.

Methods: We reviewed and adjudicated all induced ventricular fibrillation (VF) episodes and spontaneous device-stored episodes that satisfied rate and duration criteria in a programmed ventricular tachycardia (VT)/VF therapy zone.

Beat-to-beat variations in activation-recovery interval derived from the right ventricular electrogram can monitor arrhythmic risk under anesthetic and awake conditions in the canine chronic atrioventricular block model.

Background: In the chronic atrioventricular block (CAVB) dog model, beat-to-beat variation of repolarization in the left ventricle (LV) quantified as short-term variability of the left monophasic action potential duration (STV) increases abruptly upon challenge with a proarrhythmic drug. This increase occurs before the first ectopic beat (EB), specifically in subjects who demonstrate subsequent repetitive torsades de pointes arrhythmias (TdP).

Objective: The purpose of this study was to demonstrate that STV is feasible to monitor arrhythmic risk through use of the intracardiac electrogram (EGM) derived from the right ventricular (RV) lead from pacemakers or implantable cardioverter-defibrillators.

Biventricular Paced QRS Area Predicts Acute Hemodynamic CRT Response Better Than QRS Duration or QRS Amplitudes.

Introduction: Vectorcardiographic (VCG) QRS area of left bundle branch block (LBBB) predicts acute hemodynamic response in cardiac resynchronization therapy (CRT) patients. We hypothesized that changes in QRS area occurring with biventricular pacing (BV) might predict acute hemodynamic CRT response (AHR).

Methods And Results: VCGs of 624 BV paced electrocardiograms (25 LBBB patients with 35 different pacing configurations) were calculated according to Frank's orthogonal lead system.