VENTRICULAR-TACHYCARDIA INITIATED SOLELY BY REDUCED PACING RATE DURING ROUTINE PACEMAKER FOLLOW-UP

Ventricular arrhythmias during a pacemaker follow-up have been previou sly reported, usually in conjunction with temporary asynchronous stimu lation of a demand pace maker through magnet application or by increas ed myocardial excitability, for example, following a myocardial infarc tion. The subject of this report, an 82-year-old pacemaker patient, ha d been VVI-paced without problems for the past 11 years. As an aid in determining the sensing threshold, the pacemaker lower rate was reduce d from 70 to 40 beats/min. A ventricular tachycardia of 240 beats/min was induced, most Likely following short-long cycles; syncope resulted . To our knowledge, this is the first report of induction of a ventric ular tachycardia during pacemaker follow-up solely by reduction of pac ing rate and not by asynchronous pacing. This case demonstrates an add itional potential risk associated with pacemaker rate manipulation dur ing pacemaker follow-up.