Tachycardia after pacemaker implantation in a patient with complete atrioventricular block

Abstract

The atrioventricular (AV) node allows ante- and retrograde conduction between atria and ventricles. It is commonly assumed that these AV nodal conduction properties go hand in hand. However, ante- and retrograde AV conduction can be completely independent from each other in individual patients. We report about a patient with permanent AV block III° requiring implantation of a pacemaker. As soon as a dual-chamber device was connected to the implanted leads, a tachycardia started at the maximum tracking rate, which was subsequently reprogrammed from 120 to 170 bpm. Non-invasive electrophysiologic testing showed that this patient demonstrated 1:1 ventriculoatrial (VA) conduction up to 170 bpm leading to endless loop tachycardia (ELT) while the antegrade AV block III° persisted. This case impressively illustrates that one has to take into account that patients with antegrade AV block III° may still have a high VA conduction capacity leading to ELT. Dual-chamber devices therefore have to be programmed accordingly, activating dedicated reactions after ventricular premature beats and automatic ELT detection and termination algorithms. © The European Society of Cardiology 2007. All rights reserved.