Headphones Can Disrupt Implanted Heart Devices Three years ago, a 17-year-old reported that an iPod can disrupt a pacemaker or an implanted defibrillator. It turns out he's nearly right: It's the headphones that can cause the devices to malfunction.

Headphones Can Disrupt Implanted Heart Devices

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Now, here's some news that might make some Apple customers think twice. Two years ago, a researcher reported that an iPod can interfere with a pacemaker or an implanted defibrillator, but the story was questioned, largely because the researcher, Jay Thaker, was a 17-year-old high school student. Now, there's a new study, and it turns out Thaker was wrong but not totally. NPR's Joseph Shapiro tells the story.

JOSEPH SHAPIRO: Dr. William Maisel was intrigued by Thaker's research. Maisel is the founder of a center that studies the safety of medical devices, and he was at the scientific meeting of doctors when the Michigan high school student presented his paper.

Dr. WILLIAM MAISEL (Cardiologist, Beth Israel Deaconess Medical Center): I think it was provocative, and I think in many respects, he deserves a lot of credit for bringing the issue to the forefront and for fostering more study of the issue.

SHAPIRO: But Maisel was skeptical that an iPod or other digital music player could cause a pacemaker or defibrillator to malfunction, and a subsequent study by the federal Food and Drug Administration showed that was highly unlikely.

Still, all this got Maisel thinking about another part of the iPod: the headphones.

Dr. MAISEL: But what we did know is that portable headphones, the type of headphones that are used with MP3 players, contain powerful magnets, and magnets can interact with pacemakers and defibrillators.

SHAPIRO: Headphone magnets vibrate a speaker, and that creates the sound waves that we hear. Maisel is a cardiologist at Beth Israel Deaconess Medical Center in Boston. His study's in the new issue of HeartRhythm Journal.

The scientist was surprised when he started testing those headphone magnets: Most were very strong, more than 20 times the strength needed to interfere with a pacemaker.

Dr. MAISEL: Well, pretty quickly we realized that we were on to something because the first thing we did was we went to our local electronics store and bought every headphone that they had.

SHAPIRO: And where'd you go? You went to, like, the Best Buy in Boston?

Dr. MAISEL: Exactly. We actually did go to Best Buy. We bought eight different portable headphones that were on sale, ranging in price from less than $10 to $100.

SHAPIRO: To test those headphones, Maisel brought in 100 patients with pacemakers and defibrillators. He put the headphones on their chests and monitored the devices. In 30 percent of cases, the headphones created interference that could block the implanted cardiac devices.

But it was an easy problem to fix. You just had to keep the headphones a small distance off their chests.

Dr. MAISEL: So we advise patients to keep headphones at least three centimeters, which is 1.2 inches, away from their chest wall because we did not observe a single interaction when the devices were kept at that distance. And so what that means for patients is that they should not place headphones and drape them over their chest when they're not wearing them. They shouldn't put them in a front chest pocket or a front jacket pocket. They shouldn't have a loved one wear headphones and rest their head on top of their device. But it also means that it's okay for them to use headphones. It's okay for them to listen to music because the distance from their ear to their devices is sufficiently far that there will not be an interaction.

SHAPIRO: As for that Michigan high school student: He's no 17-year-old whiz kid anymore; he's a 19-year-old whiz kid. Jay Thaker is a junior at Michigan State University. He's continued to publish studies that look at whether iPods can interfere with medical devices.

Mr. JAY THAKER (Student, Michigan State University): I think we got people thinking about something that maybe wasn't as prevalent in the medical community before. I think it just reinforced in people's minds that with all these new technologies and with technology continually developing faster, we really have to keep an eye on how it's going to interact with these different medical devices so that we can keep patients safe and keep them aware of what's going on.

SHAPIRO: Ask Thaker what he's listening to on his iPod these days, and he has a hard time naming any music. Recently, he bought a review course for the admissions test for medical school.

Mr. THAKER: They have an MCAT review out, and I copied that onto my iPod from the CDs, and I think that's all I've been listening to. In the car, when I'm running, just nonstop, I've been listening to these CDs.

(Soundbite of laughter)

SHAPIRO: Jay Thaker takes the exams for med school in the spring. Joseph Shapiro, NPR News.

(Soundbite of music)

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