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What’s New in the Patient Safety World

October 2021

More on Smartphones and Watches Effect on Cardiac Devices



Our July 20, 2021 Patient Safety Tip of the Week  FDA Warning: Magnets in Consumer Electronics May Affect Medical Devices” warned of the risk to cardiac devices, such as pacemakers and implanted cardioverter-defibrillators (ICD’s), by magnets in some consumer electronics, like cell phones and smartwatches. A few reports of such products leading to deactivation of the cardiac devices led to a warning from the FDA (FDA 2021a).


A new study (Seidman 2021) analyzed the separation distance between consumer electronic devices that may create magnetic interference, including cell phones and smart watches, and implantable pacemakers and ICD’s where “magnet mode” can be triggered. Many 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 initiated with the use of a high field strength magnet that is placed near the implanted device placing it into a “magnet mode.”


The researchers measured static magnetic fields of the iPhone 12 models and Apple Watch at several planes in 1 cm resolution. They found that all iPhone 12 and Apple Watch 6 models tested have static magnetic fields significantly greater than 10 gauss in close proximity (1–11 mm), which attenuates to below 10 gauss between 11 and 20 mm. Translation: If placed within close proximity, those magnetic fields are high enough to place implanted cardiac devices into magnet mode. When a separation distance of 6 inches is maintained between an iPhone 12 (or Apple Watch 6), the implantable device should not be put into magnet mode.


Those findings lend credence to the recommendations in the FDA warning. The FDA provided information for patients on this issue (FDA 2021b), stating “People with implanted medical devices may want to take some simple precautions, including:


While the overall risk of a smartphone or smartwatch deactivating your cardiac device may be low, the increasing use of strong magnets in the smartphones and smartwatches certainly raises concerns. It would be pretty easy to put such a cell phone in a pocket overlying a device or inadvertently place their smartwatch in close proximity to their cardiac device and be unaware that their cardiac device is in a mode that will not save them if they have an event.


The smartphones and smartwatches are being touted for their health safety capabilities. But patients should also be made aware of this potentially detrimental threat as well.






FDA (US Food and Drug Administration). FDA In Brief: FDA Continues to Monitor the Effects of Magnets in Consumer Electronics on Implanted Medical Devices. FDA 2021; May 13, 2021



Seidman SJ, Guag J, Beard B, Arp Z. Static magnetic field measurements of smart phones and watches and applicability to triggering magnet modes in implantable pacemakers and implantable cardioverter-defibrillators. Heart Rhythm 2021; Published online: August 25, 2021



FDA (US Food and Drug Administration). Magnets in Cell Phones and Smart Watches May Affect Pacemakers and Other Implanted Medical Devices. FDA 2021






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