Phantom Pacemaker Programming *

Spurious or “phuntom” programming of programmable pacemakers may occur as the result of two phenomena. One is change in rate and/or output of the generator from an anomalous source (dysprogramming); the other is a generator response different from that intended and set on the conventional programmer (misprogramming). In either case, the result is a nuisance, at best. Conceivably, at worst, an irreversible subthreshold output could be induced. Despite wide usage of such devices, neither event has been reported, in the routine folow‐up of 95 implanted Cordis Omni‐Stanicor®† generators, we have observed three instances of dysprogramming upon application of a magnet commonly used to induce the asynchronous mode. Subsequent in vitro studies revealed magnetically induced programming reed switch vibration in 9 of 6,680 units, which could account for the in vivo observations. We also describe many instances of misprogramming, attributable, in most cases, to a faulty programmer emission count. In this series, none of the anomalies was clinically detrimental. However, anyone involved in pacemaker follow‐up should be alerted to the existence of these potentially hazardous phenomena.