The study was conducted following reports of smart phone and watch interference with implanted medical devices, such as pacemakers and cardiac defibrillators.
Implantable pacemakers and cardioverter defibrillators (ICDs) include a magnet mode designed to be used when a patient is undergoing a procedure where electromagnetic interference is possible, or when suspension of the device is necessary for medical treatment. However, this feature can also be triggered accidentally from strong magnetic fields greater than 10G, which can change how the device works and could result in serious harm to the patient.
Historically, magnets strong enough to trigger this magnet mode were very large and identifiable, such as stereo speakers or electronic motors in cordless tools. With the advent of small rare-earth magnets, however, strong magnetic fields can be found in headphones, door locks, or small phone speakers.
For the CDRH study, investigators tested the magnetic field output of all iPhone 12 and Apple Watch 6 models at varying distances from the devices. They found that all the devices have static magnetic fields significantly greater than 10G in close proximity, high enough to place implanted cardiac devices into magnet mode. However, when a separation distance of six inches or more is maintained, the phones and watches will not trigger magnet mode.
Lead investigator Seth J Seidman, MS, research electrical engineer and EMC program advisor with the CDRH, said, “Because of these results, we are taking steps to provide information for patients and healthcare providers to ensure they are aware of potential risks and can take simple proactive and preventive measures like keeping consumer electronics, such as certain cell phones and smart watches, six inches away from implanted medical devices and not carrying consumer electronics in a pocket over the medical device.
“We believe the risk to patients is low and the agency is not aware of any adverse events associated with this issue at this time. However, the number of consumer electronics with strong magnets is expected to increase over time. Therefore, we recommend people with implanted medical devices talk with their healthcare providers to ensure they understand this potential risk and the proper techniques for safe use. The FDA will continue to monitor the effects of consumer electronics on the safe operation of medical devices,” concluded Seidman.
To read the full study, click here: Static magnetic field measurements of smart phones and watches and applicability to triggering magnet modes in implantable pacemakers and implantable cardioverter-defibrillators.
Image: US Food and Drug Administration