Implantable cardioverter-defibrillators exposed to low frequency magnetic fields

This paper presents a numerical modeling study of electromagnetic interference (EMI) in implantable cardioverter-defibrillators (ICDs), exposed to low frequency magnetic fields. Initially, an analysis of the standards that consider interference in ICDs was performed, to determine the level of induced voltage that may occur when the device is exposed to such magnetic fields. A Helmholtz coil was used to generate a uniform magnetic field. The magnetic field exposure was performed for the frontal position (front to back). This position presents the worst case scenario. The induced electric fields and voltage were investigated in both a simple homogenous block (brick) and in an anatomical model (virtual phantom). The ICD´s sensitivity parameters were adjusted to minimum values (e.g. 0.2 mV for ventricular detection). This maximum sensitivity corresponds experimentally to the worst-case EMI scenarios. The results showed that magnetic fields above 5000 μT were required for the ICD to possibly present a dysfunction in the homogenous block, while they were only 1400μT in the anatomical model. These results could be informative for any proposed standards concerning the safety of ICDs (CENELEC, INCIRP) for workers as well as for the general public.