Impact of increasing current drain in a pacemaker operating during activation of the elective replacement indicator.

The occurrence of a 13.8 s episode of ventricular asystole in a patient whose VVIR pacemaker displayed the elective replacement indicator (ERI) is reported. Increasing battery current drain by VARIO testing and programming of the emergency VVI mode markedly increased battery current drain with a resultant decrease in the battery voltage below the pacing threshold. The prolonged lack of capture occurred because the lowered battery voltage could not return instantaneously to its previous level after the demand for a higher battery current drain had ceased. Rather, the battery voltage increased progressively to its previous level and successful capture was eventually regained at the previous base rate. When a pacemaker is at or near the ERI point, it is important to avoid any manipulation (including VARIO testing) that increases battery current drain so as to prevent prolonged ventricular asystole in pacemaker-dependent patients.