Abstract 13990: Disturbances of Implantable Cardioverter Defibrillators in Electro-Magnetic Fields. A Clinical Single Center Trial of 102 Patients
Objective: Investigations and simulation models indicate that electro magnetic fields (EMF, 50/60 Hz) occurring in daily life may interfere with implanted devices like ICDs. These models can give only rough estimation because the results are not validated in patient studies. In consideration of these facts it is important to investigate the risk of medically relevant disturbances of the devices in EMF, i.e. inhibition of pacing, delivery of inadaequate shocks or impairment of VT/VF detection (fig. 1). The aim of our study was to identify thresholds of electromagnetic disturbances of ICDs.
Methods: Patients were exposed to EMF using Helmholtz coils for generation of magnetic fields (max. 2500 µT) and an applied body current simulating the electric fields (max. 300 µA corresponding to 30 kV/m). Magnetic, electrical and combined fields were tested at different settings of the implants. 102 patients were tested (1-/2-/3-chamber ICDs = 73/13/16; 26 Biotronik, 10 Boston Sci., 34 Medtronic, 32 St. Jude Medical).
Results: 87 devices could not be disturbed at the maximum applied fields programmed at a nominal sensitivity. In 13/15 disturbed ICDs only the atrial lead showed an inadequate oversensing. Concerning the american maximum permissible field strengths for public exposure (IEEE; ANSI) no ICD could be disturbed by EMF on the ventricular channel and only one on the atrial channel (fig. 2).
Conclusions: Disturbances of ICDs in EMF are very rare and occure only in strong EMF. Concerning the RV-lead the risk of medical relevant interferences is very low at maximum tested field strength. Predominantly atrial leads could be disturbed because of the small intrinsic atrial signal and a corresponding poor signal-to-noise ratio by EMF. These results indicate that the accepted safety values for healthy people may be also adapted for patients with ICDs.
- © 2011 by American Heart Association, Inc.