Congenital complete heart block associated with QT prolongation

Abstract

The coexistence of congenital complete heart block and QT prolongation represents a special type of arrhythmia. The electrophysiological and clinical characteristics of this syndrome were studied in eight patients suffering from congenital AV block and QT prolongation. Data from 22 patients suffering from congenital complete heart block only, served as a control. In the study group, the appearance of a torsade de pointes type of ventricular tachycardia could regularly be observed and the tachycardial attack could usually be provoked by ventricular extrastimuli. The corrected QT time was markedly prolonged; on ventricular stimulation, at higher pacing rates the QT interval shortened, but remained significantly higher than in the control group. Syncopal attacks--with the character of polymorphic tachycardia--appeared in each patient of the study group while occurring in only three patients from the control group. Patients were given pacemaker implants (using a higher pacing rate) and long-term administration of beta-receptor blockers. The outcome was favourable; no ventricular tachycardia or syncopal attack was observed in the follow-up period.

ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

“…189,201,202 The primary benefit of pacemaker therapy may be in patients with pause-dependent initiation of ventricular tachyarrhythmias 203 or those with sinus bradycardia or advanced AV block in association with the congenital long-QT syndrome, 204,205 which is most commonly associated with a sodium channelopathy. Benson et al 206 discuss sinus bradycardia due to a (sodium) channelopathy.…”

Task Force on Sudden Cardiac Death of the European Society of Cardiology

“…The mechanism of SCD is attributed to either pauses without an escape pacemaker or pause mediated ventricular tachyarrhythmias. In the latter case and specifically in patients with CCHB and prolonged QT interval, early afterdepolarizations and dispersion of ventricular refractoriness, as a result of a pause or a long-short RR sequence, are the primary electrophysiological mechanism of fatal arrhythmias [486,487] . Undoubtedly, in patients with CCHB, a low heart rate (<50 beats .…”

Torsades de Pointes in atrioventricular septal defect

“…Down regulation of potassium channels is a proposed causal mechanism. Pacemaker implantation and administration of beta-receptor blockers provide favourable outcome, with significant reduction in ventricular tachycardia and syncopal attacks [2][3][4][5].…”