Recent testing in Europe has confirmed it remains important for those wearing pacemakers or using an ICD to keep from 6 to 8 inches between their phone and the device.

A study presented at the joint meeting of the European Society of Cardiology's European Heart Rhythm Association and Cardiostim warned those wearing pacemakers to keep a safe distance between the devices to avoid unwanted pauses in function and painful shocks.

According to Dr. Carsten Lennerz, a cardiology resident from the German Heart Center and first author for the study, pacemakers can mistake electromagnetic interference (EMI) from smartphones as cardiac signals, leading them to briefly stop working. This pause in cardiac rhythm can cause someone wearing a pacemaker to faint, while implantable cardioverter defribillators (ICDs) will see the skip in rhythm as similar to ventricular tachyarrhythmia, prompting the device to deliver a painful shock to avert the life-threatening condition.

Regulatory institutions such as the U.S. Food and Drug Administration and device manufacturers recommend, based on pacemaker testing done 10 years ago, that a distance of between 15 and 20 centimeters, between about 6 to 8 inches, be maintained between pacemakers and ICDs and mobile devices. The new testing recommends that distance be maintained, and doctors suggest that those with pacemakers also use the phone on the ear opposite to the pacemaker.

Since the initial testing, new smartphone models have entered the market and mobile network standards have been changed. New cardiac devices have also been made available.

The study Lennerz and colleagues carried out was designed to evaluate whether the recommended safety distance was still applicable, given the rise of new smartphones, network standards and cardiac devices. "From earlier studies we know that the most vulnerable phases of a call are ringing and connecting to the network, not talking, so it was important to analyse these separately," Lennerz said.

To do so, 308 patients were tapped to participate, 147 of whom were wearing pacemakers while 161 were fitted with ICDs. The subjects were then exposed to electromagnetic fields from three common smartphone models (HTC One XL, Nokia Lumia and Samsung Galaxy 3) by directly placing the smartphones on top of their cardiac devices.

All the smartphones used were hooked up to a radio communication tester and were subjected to the standard calling process. Aside from being performed in GSM, UMTS and LTE networks at maximum transmission power, all actions were also carried out at a frequency known to affect cardiac devices: 50 Hz. Electrocadiograms were then continuously recorded, checking for any interference.

More than 3,400 tests were done on EMI, or electromagnetic interference. Only one of the subjects was affected by EMI from the smartphones, whose MRI-compatible ICD wrongly detected EMI from the HTC and Nokia models on UMTS and GSM networks as intracardiac signals.

"Interference between smartphones and cardiac devices is uncommon but can occur," said Lennerz, pointing out that the current recommendation on safe distances between mobile and cardiac devices should still be followed.

"Patients with a cardiac device can use a smartphone but they should not place it directly over the cardiac device. That means not storing it in a pocket above the cardiac device. They should also hold their smartphone to the ear opposite to the side of the device implant," said Professor Christof Kolb, last author and head of the Department of Electrophysiology at the German Heart Centre.

Other concerns those wearing pacemakers might have is whether or not it is safe for them to use walking paths and bicycle routes under high-voltage power lines. While a study found it is safe, it recommends that those with the devices should avoid staying stationary under them. Those riding in vehicles should not worry about passing under high-voltage lines, the study says, because cars act as automatic shields.

Photo: David Goehring | Flickr

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