SafeR and escape junctional rhythm: A singular trigger for pacemaker-mediated tachycardia.

A 70-year-old man, who previously received a dual chamber pacemaker for paroxysmal AV block (Sorin Symphony DR 2550), was noted on telemetry to have multiple episodes of rapid ventricular pacing at approximately 120bpm. Evaluation of the telemetry strips revealed that all of the rapid ventricular pacing episodes were initiated by brief runs of escape junctional rhythm. Programmed bradycardia parameters were AAI SafeR with lower rate limit of 50bpm.