Health News

Pain Relieving Magnet Gadgets Could Spell Trouble for Your Heart

May 17, 2000 (Washington) -- Some of the magnet-containing gadgets being marketed for relief of aches and pains could prove fatal to people with implanted heart devices. Although they generate much smaller magnetic fields than their manufacturers claim, the increasingly popular 'alternative therapy' items could cause pacemakers and implanted devices that shock the heart, called defibrillators, to malfunction. That's according to a new study presented at a medical meeting here this week.

"Patients should know that if they have an implanted pacemaker or defibrillator, there is the potential for some of the therapeutic magnets out there to have an adverse effect on their device," says study leader Thomas Mattioni, MD, director of electrophysiology at the Arizona Heart Institute in Phoenix.

Every pacemaker and defibrillator contains a switch that's meant to function as a sort of "emergency cut-off." But that switch can be tripped accidentally if the device is exposed to a strong magnetic field. If that happens, says Mattioni, pacemakers will function haphazardly, possibly causing the heart to stop beating, and defibrillators won't operate -- also a deadly situation.

The researchers bought and tested several commercially available items -- including knee, arm, and shoulder wraps, a back support, and a mattress pad -- to see if the magnets they contained were strong enough to trip the switch. First they measured the magnetic strength of each item at various distances. Then they rigged a typical pacemaker with a light that would turn on when its switch was tripped, and measured how close each of the items had to get before the light came on.

"The good news is that the fields aren't as strong as they claim," Mattioni tells WebMD. "The bad news is that they could still potentially cause problems." The researchers found that the manufacturers had dramatically overstated the magnetic strength of every product. Even though every item had more than enough surface magnetic strength to trip the switch, the strength dropped so dramatically with distance that by the time the items were six inches from the pacemaker, they were essentially harmless.

So, says Mattioni, "a shoe insert, wrist bracelet, or even a belt would not be a problem," since these items are unlikely to come within a dangerous range of the implanted devices. But a neck collar, a shoulder wrap, and especially a mattress pad could present a problem. Even if used as intended, movement during sleep could bring the magnets "within inches of the device and trigger a magnet response," he says.

Both patients and doctors should be aware of the potential for trouble, Mattioni tells WebMD. Although physicians routinely advise patients with implantable devices to avoid strong magnetic fields, many are "unaware" of the increasing popularity of therapeutic magnets. Patients, for their part, should report all alternative therapy use to their physician.