Pacemaker Mediated Tachycardia

Pacemaker-mediated tachycardia (PMT), or endless loop tachycardia, is a reentrant tachycardia in which the pacemaker forms the anterograde pathway and the atrioventricular node forms the retrograde pathway, leading to a pacemaker-sensed retrograde P’ wave. It typically occurs in patients with dual chamber pacemakers in DDD mode. The rate is usually at or near the programmed upper limit. PMT can be terminated by slowing conduction through the atrioventricular node (e.g., adenosine) or activating asynchronous mode by placing a magnet over the pacing generator. Most pacemakers have programmed algorithms to prevent PMT from happening.