Cross-ventricular endless loop tachycardia during biventricular pacing

This report describes the development of an unusual pacemaker tachycardia in a patient with a conventional dual chamber pacemaker used for biventricular pacing in the VVIR mode. The atrial channel was connected to the left ventricle and the ventricular channel to the right ventricle. The tachycardia was sustained by sensing of the T wave by the "atrial channel" which triggered pacing by the "ventricular channel. " This "cross-ventricular" endless loop tachycardia is a reentrant pacemaker tachycardia like classic endless loop tachycardia and can be prevented by appropriate programming of the pacemaker.