Tag-along pacemaker

In a R-wave-inhibited pulse generator, an increased interval between pacing artifacts giving an apparently slow rate was not indicative of impending battery failure in two patients. The pacing artifacts appeared as a tag-along phenomenon following a slow idioventricular rhythm as the result of an exit block due to (1) hyperkalemia and (2) perielectrode fibrosis. Simple tests demonstrated a normally functioning R-wave sensing circuit and pacemaker.