Clues From the Device: Individualized Programming to Solve a Pacing-Facilitated AVNRT.

A dual-chamber pacemaker patient with sick sinus syndrome presented with a slow, long-RP' tachycardia. Device interrogation revealed that a spontaneous PVC reset the tachycardia, excluding atrial tachycardia. A subsequent atrial paced beat advanced the next QRS, excluding junctional tachycardia and implicating the slow pathway in the reentrant circuit. Diagnosis of AVNRT was confirmed. Shortening the AV delay terminated all episodes. This case demonstrates the diagnostic utility of pacemaker algorithms and the value of individualized programming.