Apparent failure of a precordial magnet and pacemaker programmer to convert a DDD pacemaker to VOO mode during the use of the electrosurgical unit.

Abstract

CARDIAC pacemaker failure in patients who are pacemaker dependent results in asystole, and can be catastrophic. A major concern is how electromagnetic interference (EMI) from the electrosurgical unit (ESU) will alter pacemaker function. The effects of EMI on pacemaker function are multiple. Electromagnetic interference, by itself, can reprogram some multiprogrammable pacemakers. 1-3 In addition, some pacemakers may automatically convert to the VOO (see table 1 for explanation of pacemaker code) or DOO mode. 4,5 Others may be totally inhibited. 4,5 If total inhibition occurs in a pacemaker-dependent patient, the result will be asystole. Pacemaker inhibition induced by EMI from the ESU generally responds to placement of a precordial magnet on the skin overlying the pacemaker generator. This effectively activates a magnetic reed switch within the pacemaker that converts the pacemaker to a VOO or DOO mode as long as the magnet overlies the generator unit. Atlee 4 recommends having the pacemaker reprogrammed to the VOO mode using a pacemaker programmer. In the VOO mode, the pacemaker is not expected to sense the EMI and, therefore, will continue to pace the heart asynchronously. We report a case of a pacemaker-dependent patient where EMI from the ESU produced total pacemaker inhibition, despite proper placement of a precordial magnet or use of a pacemaker programmer.