Using smartphone
Device manufacturers and regulators recommend that a distance of 15cm to 20cm should be maintained between pacemakers or ICDs and mobile phones

People using pacemakers should keep a safe distance from smartphones as signals from the handset can interfere with the implanted device leading to disastrous consequences.

Research presented at Ehra Europace -- Cardiostim by Dr Carsten Lennerz, first author and cardiology resident at the Clinic for Heart and Circulatory Diseases, German Heart Centre, Munich, shows that the external signal from a smartphone can cause the implant to pause or deliver a painful shock.

Lennerz said: "Pacemakers can mistakenly detect electromagnetic interference (EMI) from smartphones as a cardiac signal, causing them to briefly stop working. This leads to a pause in the cardiac rhythm of the pacing dependent patient and may result in syncope. For implantable cardioverter defibrillators (ICDs) the external signal mimics a life threatening ventricular tachyarrhythmia, leading the ICD to deliver a painful shock."

The study sought to evaluate whether the existing safety norms brought into effect a decade were adequate and required to be implemented with new smartphones, networks and cardiac devices.

Mobile network standards have changed from GSM to UMTS and LTE over the past 10 years, while new cardiac devices that are presently being used, include ICDs, cardiac resynchronisation therapy (CRT) and MRI compatible devices.

Manufacturers of pacemakers/ICDs and regulators at present recommend that those who are implanted with the device, maintain a distance of around 15cm to 20cm between pacemakers or ICDs and mobile phones.

Tests on patients

A total of 308 patients (147 implanted with pacemakers and 161 with ICDs, including 65 CRTs) were exposed to electromagnetic fields of three common smartphones (Samsung Galaxy 3, Nokia Lumia and HTC One XL) which were placed on the skin directly above the cardiac device.

The smartphones were tested in GSM, LTE and UMTS network bands at the maximum transmission power and at 50Hz, a frequency known to influence cardiac implantable electronic devices.

Electrocardiograms (ECGs) were recorded continuously and checked for interference during the ringing, talking and connecting phases of the smartphone.

More than 3,400 tests on electromagnetic interference were performed. One out of 308 patients (0.3%) was affected by the interference caused by smartphones, interpreted as intracardiac signals.

Professor Christof Kolb, head of the Department of Electrophysiology at the German Heart Centre, said: "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."

Power lines

From a second study on EMI, researchers suggest limiting exposure to high voltage power lines, especially for those using devices with sensitive settings.

Dr Katia Dyrda, a cardiologist at Montreal Heart Institute, University of Montreal, involved in the study said: "The International Organization for Standardization says pacemakers and ICDs should give resistance up to 5.4 kV/m (for 60 Hz electric fields) but electric fields can reach 8.5 kV/m under high voltage power lines and 15 kV/m in utility substations."

Patients are advised to avoid staying in a stationary position beneath high-voltage power lines as it could cause harm, but driving below these lines is not harmful as the car acts as a shield.

Distribution lines (lines delivering electricity to homes) are not dangerous as the 60 Hz electric field they generate is very low to impact a pacemaker.