Cell Phones vs. Pacemakers & ICDs | Study supports risk of magnetic interference
A study published in August 2021 provided further evidence of a potential risk that some cell phones and smart watches produce enough magnetic field to interfere with implanted pacemakers. This latest study supports a notification from the FDA earlier this year about the potential risk of magnetic interference between cell phones and pacemakers.
The study, published in Heart Rhythm, demonstrates that both the Apple iPhone 12 and Apple Watch 6 models produce static magnetic fields which are capable of triggering a pacemaker or implantable cardioverter defibrillator (ICD) to enter “magnet mode.” The FDA explains the utility of magnet mode:
Many implanted medical devices are designed with a “magnet mode” to allow for safe operation during certain medical procedures such as undergoing an MRI scan. These safety features are typically engaged by physicians with the use of a high field strength magnet that is placed near the implanted device placing it into a “magnet mode.” Removal of the magnetic field causes the device to return to normal operation.
The researchers added:
"When a pacemaker enters magnet mode, the device continuously paces without sensing the patient’s own heart rhythm, which can result in symptoms (such as irregular heartbeats), abnormal heart rhythms, or, rarely, more serious patient harm."
Implantable pacemakers and ICDs which meet the specifications of ISO 14117 Active Implantable Medical Devices - Electromagnetic compatibility are tested to ensure magnet mode is not triggered by static magnetic fields below 1mT (10 G). The study demonstrated that an iPhone 12 Pro Max is capable of producing a static magnetic field of 404.33 G at a separation distance of 1 mm and an Apple Watch 6 measures 983.14 G at a distance of 1mm. The researchers note that the magnetic fields attenuate to below 10 G at a separation distance between 11-20mm. A Letter to the Editor published in Heart Rhythm earlier in 2021 demonstrated that an iPhone 12, when placed over a ICD patient’s chest, immediately suspended ICD therapies until the iPhone was removed.
For this reason, the FDA recommends maintaining a minimum separation distance of 6 inches between implanted medical devices and smartphones or smart watches. The FDA notification continues:
The FDA also conducted its own testing on some products that use the high field strength magnet feature and have confirmed the magnetic field is both consistent with the publications and strong enough to turn on the magnetic safety mode of the medical devices in question. The FDA believes the risk to patients is low, and the agency is not aware of any adverse events associated with this issue at this time.
