According to a recent study published in the journal Heart Rhythm, the magnets in portable headphones may cause temporary malfunction of some cardiac devices. Therefore, the researchers suggest that patients with implantable cardioverter-defibrillators or pacemakers should not place headphones from MP3 players too close to their chests. The interference that can be caused by the headphones includes inhibition of tachyarrhythmia detection in ICDs and asynchronous pacing in pacemakers. Patients with these devices don’t need to avoid portable headphones, they should just keep them at least 3 centimeters (1.2 inches) from their chests. Cardiac arrhythmia specialists have long told patients not to place electronic equipment directly over their devices.
According to the study’s researchers, the FDA has already concluded that digital music players are unlikely to interfere with implanted devices, but not much was known about potential interference from portable headphones. In the recent study, electromagnetic levels from portable headphones exceeded levels sufficient to disable sensing in an implanted device, when the headphones were less than 2 centimeters from the chest. Most of the devices returned to normal functioning once the headphones were moved away. Patients with ICDs were more likely to have an interaction, than patients with pacemakers. The headphones’ magnetic fields were the same whether the MP3 player was turned on, or the headphones were plugged in.