The Effect of 60 Hertz Electric Fields and Currents on Implanted Cardiac Pacemakers

Abstract

To provide quantitative data on the effect of electric fields from power lines and leakage currents from household appliances on patients with -implanted pacemakers, a semi-empirical prediction method was de­ veloped. Input data to the prediction model included in vitro susceptibility bench tests on pacemakers, in vivo exposure measurements on baboons with implanted pacemakers, and nonhazardous, noninvasive tests on hu­ mans. The results show that widespread interference from 60 Hz electric fields or currents does not con­ stitute a problem for the vast majority of pacemaker patients. Several remedial approaches have been iden­ tified for the small group of patients where the possi­ bility of interference may occur. The results of the above are developed in two parts. This paper, Part I, provides basic information on 60 Hertz environments, pacemaker operation, in vitro bench measurements and in vivo studies. It is shown that in vitro measurements on pacemakers are a valid method for assessing performance of implanted units. Pacemaker sensitivity to 60 Hertz interference, arising from either household appliance leakage current or transmission line fields varies widely. The most .pick­ up occurs for a monopolar lead configuration in combi­ nation with an abdominal implant for electric field exposures or hand-to-feet body currents. The monopolar pectoral implant-lead combination is the most sensitive to horizontal electric fields or body currents. The bipolar:lead in combination with any location of pulse generator exhibits the least pickup•