November 10, 2008

Study Finds Headphones May Interfere With Pacemakers

New research shows that MP3 headphones placed within an inch of pacemakers and implantable cardioverter defibrillators (ICDs) may interfere with the devices.

In some cases they might even keep the defibrillator from delivering its lifesaving shock, according to doctors who tested them.

"Headphones contain magnets, and some of these magnets are powerful," Dr. William Maisel, who led he study, told the Associated Press.

Maisel, a cardiologist at Beth Israel Deaconess Medical Center in Boston and a heart device consultant to the federal Food and Drug Administration (FDA), presented the research on Sunday to the American Heart Association's 2008 Scientific Sessions conference.

"I certainly don't think people should overreact to this information," but it's wise to keep small electronics at least a few inches away from implanted medical devices.

"The headphone interaction applies whether or not the headphones are plugged in to the music player and whether or not the music player is on or off," he said.

Nearly 2 million people throughout the world have pacemakers, defibrillators or other devices to help regulate their heartbeats.

FDA tests conducted earlier this year found that iPods and other music players pose no threat to the devices.  However, Maisel and his colleagues wanted to know if the same was true of headphones.

They tested eight headphone models, including earbuds and those that hook over the ear, in 60 people with heart devices. The study did not test larger or noise-canceling headphones, since the size of the headphone doesn't necessarily relate to magnetic strength.  Indeed, small, portable headphones typically use neodymium, one of the most powerful and concentrated magnetic substances, said Maisel.

The researchers found that when the headphones were placed an inch from the device, interference was detected nearly 25 percent of the time - in 10 of the 33 patients with defibrillators and four of the 27 with pacemakers.

Although some patients might not feel such interference, some may have heart palpitations.  Either way, the interference could temporarily deactivate a defibrillator, preventing it from delivering a lifesaving shock if one were required.

The magnet's effect declines rapidly with increasing distance from the device, and heart device function returns to normal as soon as the headphone moves out of range.

A separate study presented at the heart conference found no threat to heart devices from cell phones using Bluetooth wireless technology.  In the past, cell phones, anti-theft security devices and other electronics have created safety concerns.  But studies generally confirm no danger to heart devices with "ordinary, prudent use," said Dr. Douglas Zipes, former president of the American College of Cardiology and a professor of cardiology at Indiana University.

"Reassurance to the public is what's warranted. I still get questions, what about my microwave?" he told the AP.

"Keep your headphones on your ears and when they're not on your ears, you shouldn't put them over your chest or your pacemaker," advised American Heart Association spokesman and device expert Dr. Kenneth Ellenbogen of Virginia Commonwealth University.


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