When positioned properly, the headphones of MP3 players won't cause problems for patients with implantable cardiac devices, a new study shows.
The paper, by a researcher at Canada's department of health, reveals that personal music player headphones and earbuds don't cause magnetic interference with implantable cardiac pacemakers or defibrillators as long as they're kept at least two centimeters from the devices.
"It doesn't matter whether the music player is on or off, or whether or not the headphones are connected to the player," said study author Kok-Swang Tan, a research scientist with the Medical Devices Bureau of Health Canada. "The static magnetic field in the headphones can still cause interference."
Tan also said that patients with the heart devices should never hang the headphones around their necks so they're lying on top of the chest or store them inside a front pocket.
Headphones and pacemakers
"Also, patients need to be sure they don't allow someone who's wearing headphones to rest his head against their chests," added Tan, who presented his findings recently at the Heart Rhythm Society's annual meeting in San Francisco.
For the study, Tan used a human torso simulator consisting of a plastic box containing 0.18% saline solution. Twenty-one pacemaker models and eight implantable cardioverter defibrillators (ICDs) were separately submerged in the saline.
With each device, Tan studied the magnetic interference of 21 models of headphones in direct surface contact with the device as well as at separation distances of up to 30 centimeters.
Tan saw no interference from any of the 21 headphones and earbuds at a distance of two centimeters or more from the surface of the devices, and none of the headphones changed the heart device settings or affected their functionality.
One US expert in heart rhythm abnormalities said the findings are an important addition to previous research. A 2009 study, for instance, revealed that personal music players were likely to cause magnetic interference with implantable cardiac devices at distances of less than three centimeters.
Keep magnets away from pacemakers
"The underlying message, which is to keep magnets away from these devices, is still the same," said Dr Daniel Morin, director of electrophysiology research at the Ochsner Clinic in New Orleans.
"But what this study does is give us a little more precision about the strength of the magnets in headphones," he said.
Morin noted that the findings would change the way he discusses magnets with his patients. "One important point I'll make is that if someone is wearing earbuds, you shouldn't allow that person to rest his or her head on your shoulder," he said.
Research presented at meetings is considered preliminary until published in a peer-reviewed journal.
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