This paper presents a magnetic-field system and the method developed for testing the immunity of the active implantable medical devices to continuous-wave magnetic fields in the frequency range up to 1 MHz. The system is able to produce magnetic fields of 150 A/m for frequencies up to 100 kHz and strengths decreasing as 1/f between 100 kHz and 1 MHz, with uniformity of the field within +/-2.5% in the volume for tests. To simulate human tissue, the medical device, together with its leads, is placed on a plastic grid in a saline tank that is introduced in the magnetic field of the induction coil. This paper offers an alternative for the injection voltage methods provided in the actual standards for assessing the protection of the implantable medical devices from the effects of the magnetic fields up to 1 MHz. This paper presents the equipment and signals used, the test procedure, and results from the preliminary tests performed at the Food and Drug Administration-Center for Devices and Radiological Health on implantable pacemakers and neurostimulators. The new system and test method are useful for the EMC research on the implantable medical devices.

This work examines the electromagnetic compatibility (EMC) of several priority medical devices, such as implanted cardiac pacemakers and implanted nerve stimulators, with the emissions from 28 different hand-held metal detectors (HHMDs). The HHMD emissions were measured and mapped to assess the waveforms, magnitude, and distribution of emission field strengths. Testing with the sample medical devices was performed using a saline filled torso simulator for the implantable type devices. Emissions from the HHMDs were observed to disrupt the function of some of the sample medical devices. One HHMD exhibited significantly higher emissions than the other metal detectors, and caused significant disruptions on several of the sample medical device. The findings and data from this work are being used to help develop standards for characterizing the performance of medical devices.