Portable electronic devices can be carried in a myriad of ways — sometimes, you may even find yourself waking up from a nap with your smartphone or headphones on your chest.
But that proximity to your chest may be a problem if you’re one of the millions of people worldwide who rely on a cardiovascular implantable device (CID), such as a pacemaker or defibrillator.
Results from a new study appearing in Circulation: Arrhythmia and Electrophysiology suggest that the magnetic fields surrounding several Apple and Microsoft devices may be strong enough to interfere with such CIDs, which contain sensors that may respond to magnets when in close contact.
“This study shows that magnetic interactions with pacemakers and implantable cardiac devices are not limited to smartphones, but can occur with many other electronic portable devices,” says Corentin Féry, a research associate at the University of Applied Sciences and Arts Northwestern Switzerland.
Measuring magnetic fields
Féry, who is lead author on the study, says that he and his colleagues focused on this research in collaboration with University Hospital Basel after a 2021 paper reported interactions between the magnetic field from the iPhone 12 Pro Max and CIDs. The researchers in those studies observed clinically identifiable magnetic interference in some individuals with CIDs. Féry decided to replicate that work and expand it to include other portable electronic devices.
CIDs are designed with a magnet mode that’s used when a patient is undergoing certain medical procedures, such as an MRI scan. According to the International Organization for Standardization, a CID should not switch into magnet mode below 10 gauss (10 G), a standard recognized by the US Food & Drug Administration (FDA). The 10 G isogauss line identifies the volume in which the magnetic field of a device exceeds 10 G and into which a cardiovascular implantable device should not penetrate (for reference, 10 G is approximately one fifth the gauss rating of a refrigerator magnet).
Féry and his colleagues measured the magnetic fields around the iPhone 12 Pro Max, Apple AirPods Pro with charging case opened and closed, Apple Pencil 2nd Generation and the Microsoft Surface Pen. The magnetic mapper they use to delineate the 10 G isogauss line measures the magnetic fields around portable electronic devices using numerous magnetic sensors on three axes. The mapper, the researchers say, accomplishes the same task as a magnetic probe but faster and more accurately.
The researchers’ results suggest that individuals with CIDs should keep the portable electronic devices tested in this study at least one inch away — 2 cm for Apple devices and 2.9 cm for the Microsoft Surface Pen, to be more precise — from their CIDs to avoid activating magnet mode. This is well within Apple’s own recommendation of six inches (more information on product safety is reported in the “Important Safety Information” sections of the user guides for Apple products).
The American Heart Association also suggests that patients avoid keeping cell phones and similar portable electronic devices in a front chest pocket and to use these devices on the side of the body opposite an implanted device.
Raising awareness
So, what’s new? Though modern smartphones already contained magnets and emitted signals that patients with implanted devices needed to be aware of prior to the iPhone 12 Pro Max, teardowns show that this phone and ones like it have more magnets in them than in earlier versions. Apple’s wireless charging technology, MagSafe, also uses permanent magnets placed around the iPhone 12’s internal charging coil to quickly charge devices.
And, while patients with CIDs are already recommended to keep portable electronic devices that may create magnetic interference at least six inches away from implanted medical devices, the researchers say that these magnet-containing portable electronic devices are now ubiquitous. Some devices may be nonchalantly placed in a shirt pocket or on the chest, switching a patient’s CID to magnet mode.
“The six-inch limit [recommended by the FDA] is high and reaching 10 G at this distance with portable electronic device magnets is very unlikely. On the other hand, implant wearers can without realizing a potential risk, go below six inches with portable electronic devices including magnets; for example, the Microsoft Surface Pen can be put in a shirt pocket,” says Féry.
One major limitation of the study was that the team measured the magnetic fields and their influence on cardiovascular implantable devices ex vivo.
“The skin and the depth of the implant in the patient have an influence on a patient-specific minimum safety distance between the skin and the portable electronic device,” Féry says. “The distances we provide represent the worst case that one can have, because it simulates an implant that would be directly at the same level as the epidermis.”
Electronic gadgets can interfere with pacemakers and defibrillators, study reveals
Currently, the researchers are testing other portable electronic devices, such as smart watches and electronic cigarettes. They also hope to raise awareness: historically, magnets strong enough to trigger the magnet mode of a cardiac implantable device were easy to steer clear of. Now, small rare-earth magnets are used inside everyday technologies.
“We hope to raise the awareness of doctors and patients with cardiovascular implantable devices of the risk of disabling medical device therapy by portable electronic devices,” Féry says. “They should know that the risk is more widespread than previously thought and that it involves different categories of objects.”
