Reliability of electromagnetic filters of cardiac pacemakers tested by cellular telephone ringing Alexandre Trigano, MD, a Olivier Blandeau, BS, a Christian Dale, PhD, b Man-Fai Wong, PhD, b Joe Wiart, PhD b a From the Department of Cardiology, Centre Hospitalier Universitaire de Marseille, Marseille, France, and b Department of Research and Development of France Telecom, Issy les Moulineaux, France. BACKGROUND State-of-the art cardiac pacemakers are protected against radiofrequency signals. Al- though there have been earlier clinical and in vitro reports of cellular phone interference with implantable devices, only a few studies have been performed in recent years. The ringing phase of digital GSM or PCS cellular phones includes a brief period of peak radiated power. OBJECTIVES This study tested the protection offered by electromagnetic filters of cardiac pacemakers against cellular phone ringing. METHODS We performed 330 consecutive tests in 158 patients at the time of routine examination in our pacemaker follow-up clinic. The programmed parameters remained unchanged before testing. During electrocardiographic monitoring, 2 single-band digital cellular phones consecutively placed over the pacemaker pocket each received a call. The phone systems tested were 1) GSM at a maximal power output of 2 W, operating on a 900 MHz carrier frequency, and 2) PCS at a maximal output of 1 W, operating on a 1800 MHz carrier frequency. RESULTS Interference was noted in only 5 tests, due to interaction by the GSM system with 4 unprotected pacemaker models. The GSM test was negative in 12 other tests of identical pulse generator models. The overall incidence of interference was 1.5% of tests. CONCLUSIONS Interference by cellular phone ringing occurred only with unprotected pacemaker models. Standard programming of these unprotected models was associated with a low incidence of interference. (Heart Rhythm 2005;2:837– 841) © 2005 Heart Rhythm Society. All rights reserved. Introduction Interference with cardiac pacemakers by cellular tele- phones was recognized in 1994 and, over the subsequent 5 years, prompted several clinical and in vitro studies. 1–7 Few data have since been published. In 1997, a North American multicenter prospective crossover study of 980 patients reported a 20% incidence of all types of inter- ference. Compared to digital systems, analog cellular telephones caused the lowest rate interference, and spe- cific electromagnetic filters in state-of-the art pacemaker models reduced or eliminated the risk. 2,4 Three of the five major pacemaker brands included in these studies are no longer implanted. 4 Digital phone systems have become prevalent worldwide. The rapidly evolving technology of implanted medical devices and wireless communication systems justifies ongoing surveillance by clinical and bench research. Despite the broadly diffused recommen- dations made to pacemaker recipients, mobile phone ringing in close proximity to the pocket of implanted devices remains a likely daily life event. According to the Global System for Mobile Communication (GSM) and Personal Communication Services (PCS) standards, the ringing phase includes a brief period of maximum field radiation. 8 The objective of this study was to assess the vulnerability of pulse generators to cellular phone ringing in the population currently followed by our pacemaker clinic. Patient population and methods The study design was approved by the Ethical Committee for Human Research of Marseille, France. All patients who presented for routine ambulatory pacemaker fol- This work was supported by the Assistance Publique-Hôpitaux de Marseille, Department of Clinical Research, Marseille, France. Address reprint requests and correspondence: Dr. Alexandre Trigano, Centre Hospitalier Universitaire Nord, 13915 cedex 20, Marseille, France. E-mail address: alexandre.trigano@mail.ap-hm.fr. 1547-5271/$ -see front matter © 2005 Heart Rhythm Society. All rights reserved. doi:10.1016/j.hrthm.2005.03.011