pacemaker

A new study conducted by German Heart Centre scientists has found that cardiac device wearers must maintain a safe distance from smartphones to avoid unwanted painful shocks or pauses in function.

Comprising 308 patients, including 147 pacemakers and 161 implantable cardioverter defibrillators (ICDs), the study evaluated whether the recommended safety distance was still compliant with new smartphones, networks and cardiac devices.

Device manufacturers and regulatory institutions such as US Food and Drug Administration recommend a safety distance from 15cm – 20cm between pacemakers or ICDs and mobile phones.

During the study, participants were tested using Samsung Galaxy 3, Nokia Lumia and HTC One XL in GSM, LTE and UMTS systems at maximum transmission power and at 50Hz, a frequency believed to cause interference.

"Device manufacturers and regulatory institutions such as US Food and Drug Administration recommend a safety distance from 15cm – 20cm between pacemakers or ICDs and mobile phones."

Electrocardiograms (ECGs) were recorded continuously and monitored for interference. More than 3,400 tests on electromagnetic interference (EMI) were performed.

Only one of 308 patients was found to be affected by EMI caused by smartphones that were placed on the skin above the medical device.

The patient’s MRI compatible ICD misdetected electromagnetic waves from the Nokia and HTC smartphones operating on GSM or UMTS as intracardiac signals.

German Heart Centre Clinic for Heart and Circulatory Diseases first author Dr Carsten Lennerz said: "Interference between smartphones and cardiac devices is uncommon but can occur so the current recommendations on keeping a safe distance should be upheld.

"Interestingly, the device influenced by EMI in our study was MRI compatible, which shows that these devices are also susceptible."

The centre also conducted a second study on EMI in response to public concerns about bicycle routes and walking paths under high voltage power lines of more than 230kV, and whether these are safe for patients with cardiac devices.

Exposing 40 cardiac devices, including 21 pacemakers and 19 ICDs to electric fields of up to 20kV/m in a high voltage laboratory, the study did not find any significant difference in EMI thresholds.

University of Montreal, Montreal Heart Institute cardiologist Dr Katia Dyrda said: "There is no need for patients with a pacemaker or ICD to avoid crossing under high voltage power lines (> 230kV) but patients should avoid staying in a stationary position underneath them."


Image: An x-ray image of an installed implantable cardioverter defibrillator showing wire routing. Photo: courtesy of Sunzi99~commonswiki.