Can Your Smartphone Deactivate a Defibrillator or Pacemaker? Revisited.
Back in October, 2020, MacRumors found an Apple support document reassuring customers that:
“Though all iPhone 12 models contain more magnets than prior iPhone models, they’re not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models.” (Apple)
In January, 2021, cardiologists from the Henry Ford Hospital demonstrated that waving an iPhone 12 over the chest area where a defibrillator was implanted could deactivate the device.
There are two types of implantable cardiac devices: an Implantable Cardioverter Defibrillator (ICD) and a pacemaker. Both help monitor a patient’s heart rhythm and can automatically correct abnormal heart rhythms or rates if certain thresholds are met. If a heart is beating too fast, too slow, or too irregularly, patients can have increased risk of mortality, including sudden cardiac death.
So when our phones can render a life-saving device useless, people start to pay attention. Within a few days, Gizmodo, 9to5 Mac, MacWorld, and others reported the single-person-investigation from the Henry Ford Hospital. The overall tone was that people should consult their physicians before using their smartphones if they have one of these implantable devices.
But, if you have an ICD or pacemaker, this is probably old news (see this top comment from Hacker News). The American Heart Association posted a list of devices that can interfere with ICDs and pacemakers, ranging from anti-theft security systems in malls to MP3 players (remember those?!) to security checkpoints in airports. Manufacturers of ICDs and pacemakers also publish their own lists with much more details on how to live with them (Medtronic and Boston Scientific). Most sources also recommend patients to keep their phones away from their left chest area.
How can a phone make a pacemaker/ICD malfunction?
“EMI, or electromagnetic interference, is the interference caused by one electrical or electronic device to another by the electromagnetic fields set up by its operation” Electronics Notes
Simply put, EMI can come from our smartphones or any other electronic device. EMI can lead to issues with tracking the heart rate or rhythm by a pacemaker or ICD. These issues can lead to scenarios where an ICD mus-interprets an EMI as a normal heart beat instead of an abnormal heart beat or rhythm, or a scenario where a pacemaker doesn’t pace at the right interval (Abbot, Journal of Arrhythmia, Table 1). Because pacemakers and ICDs are often implanted as life-saving measures, a disruption in their proper functioning can be life-threatening.
Did we not study this until now?
The question of electromagnetic interference from everyday devices with ICDs and pacemakers has been asked for decades, dating back to the 1980s. But, cell phones did not become commonplace until the mid- to late-1990s. In 1997, a study published in the New England Journal of Medicine examined how much interference cellphones had on pacemakers in 980 patients. Their conclusion was, as long as the cell phone was held at a “normal position” (aka next to the ear), then the interference was not clinically significant. But we have come a long way since the days of “Personal Communication System-1900 [PCS-1900]” or “Code Division Multiple Access [CDMA]” (two of the cell phones tested in the 1997 study). What about more recent studies?
A 2015 study looking at Samsung Galaxy S3, Nokia Lumia, HTC One XL in 307 patients with ICDs showed 0.3% of electromagnetic interference. In September, 2020, a study published in the Journal of American College of Cardiology investigated whether iPhone 6's or Apple Watch 1st gen’s could affect ICDs and pacemakers in 148 patients. They placed the phones over the left chest area (where ICDs/pacemakers are usually implanted) and tested standby, dialing, internet connection. They observed one case of interference on a pacemaker with the iPhone but none with the smartwatch.
So that’s all good news, right?
Sort of. It seems that cellphones, in general, should not pose too much risk to a patient with a pacemaker or ICD. The FDA advises patients to use cellphones with some distance, such as using it on the opposite ear and avoiding putting the phone in your left chest pocket.
But, our smart devices are getting more complex, and how we use them is also evolving. In 2019, Chicago Tribune found that iPhone 7s emitted radiofrequency radiation over the legal limit. The industry standard was to measure radiation about an inch away from the body, which was set in 1990s when cellphones were often at the hip level in belt clips. However, the Chicago Tribune tested devices are more realistic distances like when we put our phones in our pockets, or about 5mm away from the body. Just like the team at Chicago Tribune, we should also consider new ways of testing EMI from smart phones and smartwatches as well.
About three weeks before the Henry Ford Hospital single-person study was published, cardiologists at Rhode Island Hospital/Brown University published a case report where magnetic wristbands from Fitbit and Apple Watch could deactivate an ICD within as little as about an inch. While these reports are isolated incidents and have not undergone rigorous scientific investigation, it is worthwhile noting the rise in magnetic devices and the need for future investigations on their potential to cause significant EMI.
For now, common sense shall prevail. Keep your smart devices at a safe distance. Here are some recommendations from trusted sources:
