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Patient Safety Tip
of the Week
July
20, 2021
FDA
Warning: Magnets in Consumer Electronics May Affect Medical Devices
The
FDA has raised concerns that magnets in some consumer electronics, such as cell
phones and smartwatch wristbands, may affect pacemakers, implantable
defibrillators, and other medical devices (FDA 2021a). The
FDA states “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 health care provider to ensure they understand this potential risk and
the proper techniques for safe use.”
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.” But
there have been recent case reports where magnets in certain cell phones or
smartwatches or fitness bands have deactivated devices such as implantable
cardioverter-defibrillators (ICD’s).
The FDA also provides information for
patients on this issue (FDA 2021b), stating “People with implanted medical devices may want to take some simple
precautions, including:
- Keep
the consumer electronics, such as certain cell phones and smart watches,
six inches away from implanted medical devices.
- Do
not carry consumer electronics in a pocket over the medical device.
- Check
your device using your home monitoring system, if
you have one.
- Talk
to your health care provider if you are experiencing any symptoms or have
questions regarding magnets in consumer electronics and implanted medical
devices.”
The FDA patient advisory goes on to say that,
when near high strength magnets, devices with a magnetic safe mode could stop
working or change how the device works. An example is that a cardiac defibrillator
may be unable to detect tachycardia events, or it may change the operational
mode of the devices such as turning on asynchronous (i.e., two or more events
not happening at the same time) mode in a pacemaker.
FDA emphasizes the following for patients: “to
avoid interference between cell phones and smart watches and your heart device,
keep them at least six inches (15 centimeters) away from implanted medical
devices. Also, do not place cell phones, smart watches, and other consumer
electronics close to your implanted medical device.”
Based
on concerns that the new magnet in the iPhone 12 with MagSafe
compatible cases might affect implantable cardioverter-defibrillators (ICD’s),
researchers at Henry Ford Heart & Vascular Institute tested the hypothesis on
a patient with a Medtronic ICD (Greenberg 2021). Once the iPhone was brought close to the
ICD over the left chest area, immediate suspension of ICD therapies was noted
and persisted for the duration of the test. This result was reproduced multiple
times with different positions of the phone over the pocket.
Asher
et al. (Asher 2021) found that a patient’s ICD had reverted to
magnet mode after she slept wearing an Apple Watch. They subsequently conducted
tests and found both Fitbit and Apple Watch wristband magnets could deactivate
the ICD up to distances of 2.4 and 2.0 centimeters, respectively.
Apple
recently published a list of its devices that patients should keep away from
their pacemaker or other medical devices (Apple
2021). It is surprising how many Apple products
have magnets. The list includes not only the iPhone 12 and its MagSafe accessories, but also Apple Watches, AirPods and their charging cases, various iPads, Beats, various
Mac models and accessories, and HomePods.
Apple
notes “Under certain conditions, magnets and electromagnetic fields might
interfere with medical devices. For example, implanted pacemakers and
defibrillators might contain sensors that respond to magnets and radios when in
close contact. To avoid any potential interactions with these types of medical
devices, keep your Apple product a safe distance away from your medical device
(more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly
charging). Consult with your physician and your device manufacturer for
specific guidelines. If you suspect that your Apple product is interfering with
your medical device, stop using your Apple product and consult your physician
and your medical-device manufacturer.”
More
and more consumer electronic products are using magnets and it is not always
obvious to people that their device has a magnet that could potentially
interfere with a medical device.
While the FDA advisory says it believes “the risk to patients is low and the agency is
not aware of any adverse events associated with this issue at this time”, we
found the case described by Asher et al. (Asher
2021) to
be particularly bothersome. That case involved a 55-year-old woman with a
dual-chamber ICD because of a history of sustained ventricular tachycardia
secondary to arrhythmogenic right ventricular dysplasia. Because of a
recommendation to avoid strenuous exercise, she purchased an Apple Watch with
fitness tracking capabilities to monitor her heart rate. She sometimes wore the
watch overnight. While asleep one night, she was awoken by several beeps
emanating from her implanted cardiac device. Subsequent interrogation of the
device showed no alerts or abnormal parameters, but it was found that the
device had reverted to magnet mode, owing to magnetic interference from the
fitness watch’s wristband. No other possible sources of interference were
identified. This was replicated in the office, where interrogation of the ICD
confirmed magnetic reversion when placed in proximity to the wristband. The watch
itself did not have magnetic interference.
Had not that patient heard the beeps from her
ICD, she might not have realized her ICD would not be active if she had an
episode of ventricular tachycardia. Pretty scary!
References:
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
FDA
(US Food and Drug Administration). Magnets in Cell Phones and Smart Watches May
Affect Pacemakers and Other Implanted Medical Devices. FDA 2021
Greenberg
JC, Altawil MR, Singh G. Lifesaving therapy
inhibition by phones containing magnets (Letter
to the Editor). HeartRhythm 2021;18(6): 1040-1041,
June 01, 2021
https://www.heartrhythmjournal.com/article/S1547-5271(20)31227-3/fulltext
Asher
EB, Panda N, Tran CT, Wu M. Smart wearable device accessories may interfere
with implantable cardiac devices. HeartRhythm Case
Reports 2021; 7: 167-169
Published online December 12, 2020
https://www.heartrhythmcasereports.com/article/S2214-0271(20)30274-8/fulltext
Apple.
About potential magnetic interference with medical devices. Apple Support 2021;
June 25, 2021
https://support.apple.com/en-us/HT211900
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