• Thomas Wolber, Salome Ryf, Christian Binggeli, Johannes Holzmeister, Corinna Brunckhorst, Roger Luechinger, and Firat Duru.
• Cardiovascular Center, Cardiology, University Hospital, Zurich. thomas.wolber@usz.ch
• Heart Rhythm. 2007 Jan 1; 4 (1): 1-4.

BackgroundMagnetic fields may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets, which are small in size but produce strong magnetic fields, have become widely available in recent years. Therefore, NdFeB magnets may be associated with an emerging risk of device interference.ObjectiveWe conducted a clinical study to evaluate the potential of small NdFeB magnets to interfere with cardiac pacemakers and ICDs.MethodsThe effect of four NdFeB magnets (two spherical magnets 8 and 10 mm in diameter, a necklace made of 45 spherical magnets, and a magnetic name tag) was tested in forty-one ambulatory patients with a pacemaker and 29 patients with an ICD. The maximum distance at which the magnetic switch of a device was influenced was observed.ResultsMagnetic interference was observed in all patients. The maximum distance resulting in device interference was 3 cm. No significant differences were found with respect to device manufacturer and device types.ConclusionSmall NdFeB magnets may cause interference with cardiac pacemakers and ICDs. Patients should be cautioned about the interference risk associated with NdFeB magnets during daily life.

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