title: The interference threshold of unipolar cardiac pacemakers in extremely low frequency magnetic fields.
abstract: The effective induction loop area of implanted cardiac pacemaker (CPM) systems in magnetic fields was determined. The results were verified in a tank model placed in the centre of a Helmholtz-coil-arrangement. Both a left and a right pectorally implanted unipolar dual chamber CPM system were simulated. On this basis and with the results of benchmark-tests the interference thresholds for a collection of modern CPMs in extremely low frequency (ELF) magnetic fields were estimated. The investigations clearly showed that there are two loops, the CPM-lead-tissue-loop and the body loop, responsible for the magnitude of the disturbance voltage on the input of a cardiac pacemaker. The effective induction loop areas rangedfrom 100 to 221 cm2. For a left pectorally implanted, atrially controlled CPM system the interference thresholds for the magnetic induction lay between 16 and 552 micro T (RMS) for frequencies of the magneticfield between 10 and 250 Hz. Thus, there is a limited possibility for an interference of implanted CPM by ELF magnetic fields in everyday life.
authors.affiliation: femu -RWFH Aachen, Pauwelsstrasse 20, 52074 Aachen, Germany. scholten@femu.rwth-aachen.de
authors.forename: A
authors.initials: A
authors.lastname: Scholten
authors.forename: J
authors.initials: J
authors.lastname: Silny
mesh_terms: D000328:Adult; D004553:Electric Conductivity; D004574:Electromagnetic Fields; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D010138:Pacemaker, Artificial