Recurrent ventricular tachycardia induced by an atrial synchronous ventricular-inhibited pacemaker

Atrial synchronous pacemakers have been known to cause a variety of cardiac arrhythmias. Of particular concern are those arrhythmias involving a pacemaker stimulus occurring on a T wave, because these may lead to ventricular tachycardia. The Medtronic 2409 ASVIP pacemaker is an atrial synchronous pacemaker with several features designed to decrease the likelihood of such arrhythmias. We report a patient in whom a normally functioning Medtronic 2409 ASVIP pacemaker, despite these features, induced recurrent ventricular tachycardia. Conditions which predisposed this patient to pacemaker-induced re-entrant arrhythmias are discussed.