I'll give some context here, since I put magnets on people's pacemakers fairly often. Magnets for at least 10 years now is a standard, controlled way to trigger a secondary mode in a pacemaker/defibrillator. Almost always, if the device has both pacemaking and defibrillating capability, the magnet will turn off the ICD (although it is possible to program other behaviors). This allows clinicians to easily stop a patient from being defibrillated inappropriately. That sort of thing could happen during malfunction, electrical interference from cautery tools during surgery near the device, or refractory shockable rhythms.

If there is no defibrillating capability, magnets usually (although not always) put the device into an asynchronous mode. This presents the (extremely unlikely) risk of something serious, like R-on-T, where an electric pulse could be sent to the heart at exactly the wrong time, leading to a life-threatening arrhythmia. More commonly, it means the heart is less effective at pumping blood but probably still within allowable, if not optimal for long periods of time, output.

In both cases, unless the device is programmed strangely, the device resumes normal function when removing the magnet. However, there's the theoretical risk of some sort of malfunction-- so when switching modes with a magnet my practice is to refer patients to getting their devices checked out afterwards. Obviously, if something triggered the "magnet mode" surreptitiously, it may not be noticed until some time later, particularly in patients who are not being actively followed by medical care.

I didn't mention it's actually kind of difficult to getting a magent over these things. I generally tape it over the area that the pacemaker is in, but you have to watch for it moving because, well, it's hard to stick something on somebody's skin. Pacemakers are generally put in the left upper chest, sort of between the nipple and the clavicle. The idea you should have is-- well-- it's not easy to trigger this even with a purpose-built magnet in a slightly-higher-then normal breast pocket. But, still possible of course, and the results could be disastrous, particularly in the event of a malfunction.

The practice of using magnets is kind of universally and internationally understood by medical practitioners and device manufacturers. Which means, transitioning away could cause some harm just by medical errors. I don't think a solution to this is particularly easy, although many devices now get regular interrogations which would show if iPhones actually are triggering the mode switch. Which sort of means, iPhone "interference" could happen but probably isn't really happening as far as anyone knows.

It's worth noting that almost anything with a magnetic field can interfere with a pacemaker, for instance induction hobs. Given the pervasiveness of, well, magnets (!), it's probably worth investing in pacemaker research which takes this into account ...

I have a pacemaker. Rule from the start: keep cell phones 6” away from it, minimum, always. Radio interference at very close range is a potential problem.

This article, while interesting and a reminder, just continues the rule.

Tangent: a few years back I got an electric car. After delivery, I read the manual - every other page had warnings for patients with implanted electronic devices. Doc & I were intrigued, discussed it often, and there was never a problem.

At the moment Apple support site states 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.

https://support.apple.com/guide/iphone/important-safety-info...

It would be interesting to verify this, i.e. compare the risk of interference for iPhone 11 and iPhone 12.

> Once the iPhone was brought close to the ICD over the left chest area, immediate suspension of ICD therapies was noted which persisted for the duration of the test.

Yeah so if you have a pace maker, try not to put magnets near your heart. The main practical impact for smart phone users with pacemakers seems to be that you shouldn’t carry a phone with a magnet mount in your breast pocket.

The article also mentions WHY pacemakers are so sensitive to otherwise benign levels of magnetism:

> All ICD’s have an in-built switch (Reed switch, Hall-effect sensors, Giant magneto sensitive resistors or coils) which respond to an externally applied magnetic field.

It’s not clear from the article what function these magnetic sensors provide. I suspect it’s either a way for the internal device to interface with an external control circuit or just a minimally invasive off switch.

It took a while for me to parse the title...

So the key takeaway is: if you have a pacemaker or an implanted defibrillator, don't put your phone in your breast pocket? But I imagine people are already told to avoid that, just to minimize the risk of radio interference? Of course, this turns a remote possibility of impacting the functionality into a near-certainty (if the magnet is strong enough).

BTW these iPhones are not the first phones that contain magnets. The Moto Z range, which has been around since 2016, has accessories ("Moto Mods") that are attached magnetically. The magnets are in the accessories, but since one backplate is shipped with the phone, most people will probably have that attached.

Editorialized title. The actual is:

Life Saving Therapy Inhibition by Phones Containing Magnets

The article is about the iPhone 12. Just pointing out that magnets aren’t specific to the iPhone.

previously: https://news.ycombinator.com/item?id=25677717

The original, full article is

https://www.heartrhythmjournal.com/article/S1547-5271(20)312...

Does anyone know if magsafe is still patented? I checked many many years ago and it was, which was why I couldn't find other vendors offering it, but has that patent somehow last over 20 years?

Seems like a failure in pacemaker design? The pacemaker kill switch should simply need much stronger magnets so there is no confusion between mobile phone or the kill switch key.

To spin this in Google's Employee Activist terms (eg, "Data Violence"), Apple's hardware design is Literally™ Engaging in Senicide.

Seems like a big suit incoming

It isn't hard to make them triggered a different way, it is that it is hard to make them reliable enough and triggered a different way. They are designed to be triggered this way because it makes them simple. They are hard to service (requires surgery) and need to be triggered reliably when they are bring triggered. To achieve this, they are made as simply as possible, so have a simple trigger mechanism. Users of them are then told that they have to avoid this situation, by being very careful. One of the instructions anyway is to not keep a phone near them, because of concerns about RF interference. It isn't a case of making another way to trigger pace-makers, it is a case of making a way that is extremely unlikely to fail to work and will remain like that for decades, and where equipment to do it is very cheap. It will then take decades for there not to be people with these devices walking around. If they are changed to work a different way, you also need to equip hospitals around the world with a way to trigger them. Basically, it is really impractical, and it is not as much of a problem as you might think because users should already be hyper aware of the danger of this. Anything you do to change it has a huge risk of killing them because of failing to work if it turns out to be even a tiny bit less reliable after the devices have been inside people for years.

Another example of a device that would be a problem like this is my watch. Jewelry that would have similar problems is also common. Things which would be a problem if put close enough are everywhere, but this is always going to be an issue with something like this that is designed to be triggered easily and extremely reliably, and the decision has previously been taken to educate the tiny number of users of them about it rather than go through the unimaginable logistical effort of changing them now (obviously it was much easier when they were new and rare).

Edit: removed paragraph about making a warning device that I don't think is worth including here.

People don't tend to hug their hobs though...

Or, you know, a fridge magnet when carried on a pocket