MP3 headphones time bombs for ticker

By Will Dunham  |   2008-11-10  |     NEWSPAPER EDITION

HEADPHONES used with MP3 digital music players like the iPod may interfere with heart pacemakers and implantable defibrillators, United States researchers said yesterday.

The MP3 players themselves pose no threat to pacemakers and defibrillators, used to normalize heart rhythm. But strong little magnets inside the headphones can foul up the devices if placed within 3 centimeters of them, the researchers told an American Heart Association meeting in New Orleans.

Dr William Maisel of the Medical Device Safety Institute at Beth Israel Medical Center in Boston led a team that tested eight models of MP3 player headphones, including clip-on and earbud types, in 60 defibrillator and pacemaker patients.

They placed the headphones on the patients' chests, directly over the devices. The headphones interfered with the heart devices in 14 of the 60 and interference was twice as likely in those with a defibrillator than with a pacemaker.

Another study presented at the meeting showed that cellular phones equipped with wireless technology known as Bluetooth are unlikely to interfere with pacemakers.

A pacemaker sends electrical impulses to the heart to speed up or slow cardiac rhythm. The magnet, however, could make it deliver a signal no matter what the heart rate was, possibly leading to palpitations or arrhythmia, the researchers said.

An implantable cardio defibrillator signals the heart to normalize rhythm if it gets too fast or slow. A magnet could de-activate it, making it ignore abnormal rhythms instead of delivering an electrical shock.

"The main message here is: It's fine for patients to use their headphones normally, meaning they can listen to music and keep the headphones in their ears," Maisel said in a phone interview.

"But what they should not do is put the headphones near their device."