Science & Technology



Researchers probing how magnets may disable medical devices

Joe Carlson, Star Tribune on

Published in Science & Technology News

Researchers and regulators are working quickly to learn more about potentially dangerous interactions between implanted medical devices and an ever-widening array of consumer gadgets that contain powerful magnets.

The concern follows research published earlier this year that found an iPhone 12 temporarily deactivated a defibrillator when held to a patient's skin just above the implant. Though the chances of this happening by mistake seemed low, the news spurred researchers in Minnesota and around the world to action.

"We believe the risk to patients is low. … However, the number of consumer electronics with strong magnets is expected to increase over time," Dr. Jeff Shuren, director of the Food and Drug Administration's medical device division, said in a statement following a broad study by the agency in May.

A pacemaker uses mild electric pulses to keep a heart beating in normal rhythm. An implantable cardioverter defibrillator also can deliver major electric shocks for sudden cardiac arrest. Both are implanted just under the skin in the upper chest, on the right or left side.

All pacemakers and defibrillators contain magnetically controlled switches that doctors can deactivate during surgery, MRI scans and medical emergencies. That's why magnetic inference has long been a risk with heart devices.

While the risk of occurrence may be low, the consequences could be serious. If a patient unknowingly puts their heart device into "magnet mode," a defibrillator could fail to treat a fast heartbeat condition called ventricular tachycardia, which can be deadly. A pacemaker could lose its ability to sense the heart's rhythm while pacing.


Patients are coming into contact with ever-stronger magnets, journal articles warn, from the magnetic bands in FitBits and Apple Watches to e-cigarettes to special cases that charge wireless headphones. Jewelry and brooches with magnetic attachments have been known to affect heart devices, as have hospital communication badges with magnets in them.

The iPhone 12, released late last year, has been the subject of particular scrutiny because the phone model contains a circular array of powerful magnets that help align it with Apple's new MagSafe wireless charging pads and other accessories.

Reports about the iPhone 12 prompted an updated warning from Apple and rising concern among the public.

"We have received numerous calls from patients, because they are quite aware of these reports," said Dr. Jay Sengupta, an electrophysiologist and researcher with the Minneapolis Heart Institute Foundation.


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