RESISTANCE OF THE MEDTRONIC MICRA LEADLESS PACEMAKER TO 60 HZ ELECTRICAL FIELDS

Abstract

Pacemaker technology is constantly evolving. Although transvenous pacemakers have long been the standard of care, they have significant drawbacks. Thus, leadless intracardiac transcatheter pacing systems have been designed to avoid the need for pacemaker pockets and transvenous leads, and hence carry the potential to reduce associated complications. However, the risk of electromagnetic interference has not been ascertained for these devices when exposed to high electric fields, nor compared to ICNIRP’s international recommendation for general public exposure (4.2 kV/m). The goal of this study was to expose the Micra leadless pacemaker to electric field levels up to 20kV/m, to determine the electric field threshold for interference. Such high electric field levels can be encountered in industrial settings (power utility substations) and in the right of way of high voltage (735 kV) power lines (theoretically up to about 8,5kV/m at midspan). The Micra leadless pacemaker, manufactured by Medtronic, was tested in vitro, in a high voltage testing laboratory. The device was mounted in a saline tank at human torso height, and incrementally exposed to electric fields up to 20 kV/m. The device was set up in three different positions: upright, horizontal and 45°. Two devices were tested. When programmed to nominal parameters (2.8mV), and to higher sensitivities (2 mV and 0.45 mV) both Micra leadless pacemakers tested were immune to interference up to a level of 20kV/m, no matter the orientation chosen. These results are reassuring since, in the laboratory, the Micra device is immune to interference up to high electric field exposures, no matter the programmed sensitivity. As with any implantable cardiac device, there remains a need for individualized decision making for the safety of employees with a leadless pacemaker if their work environment exposes them to electric fields. For the general safety of the public, no significant concern should arise in individuals with Micra leadless pacemaker programmed to nominal settings or to higher sensitivity levels.