Clinically significant magnetic interference of implanted cardiac devices by portable headphones
Received 2 May 2009; accepted 2 July 2009. published online 10 July 2009.
Background
Little is known about the magnetic field strength of portable headphones and their potential to cause magnetic interference with implanted pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs).
Objective
The purpose of this study was to evaluate the magnetic field strength of portable headphones and to determine if they can cause clinically relevant magnetic interference.
Methods
PM or ICD function was assessed in 100 patients during exposure to eight different models of portable headphones to determine the incidence of clinically relevant magnetic interference. The magnetic field strength of the headphones also was measured in vitro.
Results
Clinically relevant magnetic interference from portable headphones occurred in 30 (30%) of 100 patients and more commonly affected ICD than PM patients (21/55 [38.2%] vs 9/45 [20.0%]; P = .048). All patients affected by magnetic interference experienced a magnet response, characterized by asynchronous pacing in PM patients and by inhibition of tachyarrhythmia detection in ICD patients. In all but one of the 30 cases of magnetic interference, removal of the headphones from the patient's chest immediately restored normal device function. Headphones with a measured magnetic field strength ≥10 gauss at 2 cm were much more likely to cause magnetic interference than were those with lower magnetic field strength (30/100 [30%] patients vs 0/100 [0%] patients; P <.0001). Magnetic interference was not observed when headphones were placed ≥3 cm from the skin surface.
Conclusion
Clinically significant magnetic interference can occur when portable headphones are placed in close proximity to implanted PMs and ICDs. Patients with such a device should be advised to keep portable headphones at least 3 cm from their device.
⁎Medical Device Safety Institute, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
†Cardiovascular Institute, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
‡Department of Computer Science, UMass Amherst, Amherst, Massachusetts
¶Department of Computer Science and Engineering, the University of Washington, Seattle, Washington
Address reprint requests and correspondence: Dr. William H. Maisel, Medical Device Safety Institute, Beth Israel Deaconess Medical Center, 185 Pilgrim Road, Baker 4, Boston, Massachusetts 02215
ABSTRACT