Electric Cars Safe With Implantable Cardiac Devices, So Far

Nancy A. Melville

May 01, 2018

Electromagnetic interference from increasingly popular electric cars presents no risk to people with cardiac implantable electronic devices (CIEDs), including pacemakers and implantable cardioverter defibrillators, new research suggests.

"Our protocol was designed to maximize electromagnetic field interference detection in a realistic assessment of the electric and magnetic fields encountered in everyday use of electric cars," said the authors.

"Nevertheless, we detected no effect on CIED function or programming."

However, first author, Carsten Lennerz, MD, from the German Heart Centre of the Technical University of Munich, Germany, said the supercharging technology being developed could have notably higher magnetic fields.

"The higher the charging current, the higher the magnetic field strength," he told Medscape Medical News. "In our study we recharged with up to 32A [amp]. However, the supercharging technology will make use up to 200 to 300A."

Their report was published online April 24 in Annals of Internal Medicine.    

The study of 108 patients with CIEDs and one of Europe's four most popular electric cars — the BMW i3, Nissan Leaf, Tesla Model S 85, or the Volkswagen e-up! — showed no evidence of electromagnetic interference with the CIEDs under a variety of different conditions.

Although devices are evolving to become highly safe, electromagnetic interference is an ongoing concern with CIEDs, posing the potential to impede function and cause such problems as pacing inhibition or inappropriate shock delivery, the researchers note.

Electric cars can be a source of electromagnetic interference; however, the cars have shielding to protect onboard computer systems, which may prevent interference with CIEDs, the authors speculated.

To evaluate the potential electromagnetic effects, patients were recruited between May 2014 and January 2015 and assigned to one of the four electric cars. Hybrid vehicles were excluded from the study to ensure electric operation only.

The patients' CIEDs included 42 different device and lead families from seven manufacturers.

The study had three parts. First, participants were seated in the front seat of cars while the car ran on a roller test, allowing for generation of the maximum electromagnetic field and for a defined protocol of acceleration and braking.

Participants were then asked to charge the same car for exposure to the typical charging process. Next, they drove the cars on public roads, with investigators measuring the strength of the magnetic field during open-road driving.

While two blinded cardiologists independently analyzed the participants' electrocardiograms, investigators measured magnetic field strength in and around the cars.

The assessments showed that while the electromagnetic field strength was generally highest during charging and increased as the charging current increased, there was no evidence of electromagnetic interference with the CIEDs, regardless of whether the patients had pacemakers or implantable cardioverter-defibrillators.

Electromagnetic field strength did not differ between the front and back seats or when measured inside the cars during the roller tests or during open road driving.

"Electric cars seem safe for patients with CIEDs, and restrictions do not appear to be required," the authors concluded. "However, we recommend vigilance to monitor for rare events, especially those associated with charging and proposed 'supercharging' technology."

Lennerz noted that the cars were tested at a variety of speeds, ranging from 30 to 120 km/h accelerations. "In general, the electromagnetic field may increase with speed or better with maximal engine power used," he said. "However, we could show that the cabins are well protected and that the electromagnetic fields are low in the cabin."

Earlier generations of CIEDs were susceptible to electromagnetic interference from a wider variety of sources, including household items, such as electric razors, microwaves, and induction ovens; however, newer devices have evolved to have better protections.

"In daily life, patients with CIEDs should be aware of antitheft surveillance systems, nongrounded electric or electronic appliances, and defective electric devices," Lennerz said.

In research published last year, Lennerz and his colleagues also tested potential interference of CIEDs from smartphones and, in the study of 307 patients subjected to more than 3300 individual tests, those results showed "incidence of electromagnetic interference from smartphones was rare (0.3%) and of minimal clinical significance."

No Interference  

Asked for comment, Dhanunjaya Lakkireddy, MD, a professor of medicine at the University of Kansas, Kansas City, said the new findings suggest levels of exposure are well within those set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), which are limited to public exposure of 200 µT and professional exposure of 1000 µT, for a varying 50-Hz sinusoidal current.

"In the current study, the maximum electromagnetic force generated even in the worst-case scenario was 116.5 µT along the charging cable, which is still well within the standards laid down by ICNIRP," Lakkireddy, who is chair-elect of the American College of Cardiology's Electrophysiology Council, told Medscape Medical News.

He added that "there have been no reports of a single case of an interference with CIEDs from electric cars, so that tells me that the electromagnetic field generated from these cars may be too small to impact the devices in any way."

Lakkireddy agreed that the increasing battery power of future generations of electric cars is an issue to be closely watched and that the only risks regarding electric cars could be in terms of defective chargers or accidental exposure to electrical outlets.

"The authors should be congratulated in systematically studying this question and putting concerns to rest," he said. "Patients should feel reassured while using their electric cars and saving the planet from emissions."

Lakkireddy noted that the newest generations of CIEDs, which have highly protective insulation and casing, have even been determined to be safe in MRI.

As reported by Medscape Medical News, the Centers for Medicare & Medicaid Services is considering expanding coverage for MRI beyond MRI-conditional cardiac devices, but Lakkireddy said the field has been slow to respond to the evidence of increased MRI safety.

"Even today, the vast number of radiology departments will not allow people with CIEDs to get MRI scans, which is unfortunate," he said.

The authors have disclosed no relevant financial relationships. Lakkireddy has consulted for most major CIED manufacturers but has no financial relationships with the companies and no disclosures to report.

Ann Intern Med. Published April 24, 2018. Abstract

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