Study of interactions between permanent pacemakers and electronic antitheft surveillance systems.

Interference of electronic antitheft systems (EASs) with pacemakers has been an object of controversy. This study was performed in 204 patients followed by our pacemaker surveillance center. The data from a total of 408-patient exposures to the EAS were analyzed. The device tested consisted of 129 DDD, 71 VVI, and 4 VDD pacemakers from seven manufacturers. The EAS studied consisted of an "acoustomagnetic" system that emits an intermittent 58-kHz signal, and a magnetic audio frequency system that emits a continuous 73-Hz signal. Complete interrogation of the pacemakers was performed before and after the consecutive exposure of the patients to both EASs. Electrocardiograms were recorded while the patients were exposed to the magnetic fields of each EAS for up to 30 seconds. One or more EAS interferences occurred in 17% of patients. EAS was observed in 26 (20%) of 129 patients with DDD, 7 (10%) of 71 patients with VVI, and 2 (50%) of 4 patients with VDD pacemakers. Over twice as many instances of EAS interference were observed with the "acoustomagnetic" system as were with the magnetic audio frequency system. Among pacemakers programmed in the DDD mode, a considerably greater prevalence of interference was observed at the atrial versus ventricular level, despite the same programmed sensing polarity in both chambers in all but one case. Sensing anomalies were the most common EAS induced disturbance, and typically lasted for the duration of exposure. In a few instances of pacing inhibition, the phenomenon was limited to 1 cycle at the onset of EAS exposure. No changes occurred in the programming of the pacemakers, and a single patient experienced palpitation during EAS induced rapid pacing. During exposure to EAS mimicking the normal use of the systems, interference with a variety of pacemakers was relatively common. However, the anomalies observed were transient and the cause of no symptom or device reprogramming. Patients should be advised to not stand unnecessarily in the close proximity of EASs.

The clinical utility of pacemaker follow-up visits.

Because of the increased complexity of modern pacemakers, pacemaker follow-up visits in specialized centers become more and more indispensable. In this study, the results of 15,000 outpatient visits to the cardiac pacing center between the years 1983-1985 are presented. In most cases (92.8%), verification of normal function was made; however, mandatory reprogramming was required in 1.2%, and hospitalization for various reasons was required in 6% of visits. Careful outpatient monitoring of pacemakers is therefore very important for detecting early or late pacemaker complications.