MP3 Headphones May Cause Achy Breaky Heart

Doctors measured the electromagnetic effects of eight different models of clip-on earphones and ear buds containing the magnetic substance neodymium, which is used in most portable headphones.

When placed close to the heart, such as in a shirt pocket or even draped around a neck, headphones containing magnets blocked implantable heart devices from searching for irregular heartbeats, according to Dr. William Maisel of Boston-based Beth Israel Medical Center and Harvard who presented his findings at the AHA meeting.

"For patients with pacemakers, exposure to the headphones can force the device to deliver signals to the heart, causing it to beat without regard to the patients' underlying heart rhythm," said Maisel in a statement. "Exposure of a defibrillator to the headphones can temporarily deactivate the defibrillator."

Approximately 23 percent of the study participants saw an abnormal reaction when the earphones were placed within 1.2 inches from the heart device. When earphones were placed a bit further from the heart, magnetic strength dropped dramatically, Maisel said.

According to his findings, Maisel said that MP3 players themselves did not cause electromagnetic interference, and said that people should not panic but exercise caution.

In separate studies whose findings were reported at the AHA meeting, doctors said that pacemakers or implanted defibrillators were not affected by iPhones, iPods, Bluetooth headsets.