Harvard Heart Letter

Cellphone safety with a pacemaker

Keep your cellphone atleast five inches away from your pacemaker or ICD.

Image: Thinkstock

Ask the Doctor

Q. I've heard that my smartphone might interfere with my pacemaker. What exactly can happen?

A. The possible risk—which is very low—is that an implanted device might misinterpret the electromagnetic signal from a nearby cellphone. Both pacemakers and implantable cardioverter-defibrillators (ICDs) may be vulnerable.

With a pacemaker (which helps start or regulate a slow heartbeat), interference from the smartphone might be mistaken for a signal from the heart, causing the pacemaker to temporarily stop working. That might cause you to faint.

ICDs are usually implanted in people who are at risk of abnormal rhythms in the heart's lower chambers, known as ventricular arrhythmias. If the device detects a life-threatening arrhythmia, it delivers a high-energy shock to jolt the heart back into a normal rhythm. But if a smartphone signal mimics a dangerous arrhythmia, the ICD might deliver an unnecessary shock.

The FDA recommends that people keep their cellphones at least five to seven inches away from a pacemaker or ICD. This warning was based on devices available a decade ago. Even so, a recent European study confirmed that the recommended safety distance may still be relevant with newer-model smartphones, networks, and cardiac devices.

To be on the safe side, avoid storing your phone in your shirt pocket. And when making calls, hold the phone to the ear opposite the side of your pacemaker.

-- Dr. Deepak Bhatt
Editor in Cheif, Harvard Heart Letter