Cardiac arrhythmias related to artificial pacemakers

Abstract

Summary Various cardiac arrhythmias related to artificial pacemakers are described in detail, and representative electrocardiographic illustrations are presented. The importance of recognizing malfunction of various pacemakers has been emphasized. An early manifestation of malfunction should be suspected even when the pre-set rate is altered by only one or two beats in either direction by a precise measurement. Earlier model pacemakers were designed to increase their pacing rate when battery exhaustion approached (“run-away pacemaker”), whereas a slowing of the pacing rate results from battery depletion in most of the newer models. In the latter circumstance, a slowing of the pacing rate may be associated with irregular impulse discharge and exit block of varying degree. The run-away pacemaker is usually considered a medical emergency for which cutting the electrode wires is often a life-saving measure. Although artificial pacemaker-induced ventricular fibrillation (R-on-T phenomena) is considered to be relatively uncommon, the mortality rate among patients with artificial pacemaker (fixed rate)-induced parasystole is 5 times higher than that among patients with pure artificial pacemaker rhythm.