You really should not. 60 beats per minute means that in ten years the leads of a pacemaker will be bent *315 million* times. That's an order of magnitude higher than we typically test fatigue resistance, and even if we were that confident about being able to produce flawless materials, there are millions of different enzymes and acids and temperature fluctuations in the body. Any one of those could impact the fatigue resistance.
Additionally, any kind of implanted device is significantly prone to a wide range of problems that range from inconvenient to devastating. The human body is very hostile to foreign objects, often with few warning signs. Clots and fibrous capsules (and eventually, calcified capsules) form around ANY implant, and that's the best case problem.
Titanium is extremely biocompatible. It forms a thinner capsule than most materials. It integrates with bones beautifully, due to surface treatments that allow bone to grow into microscopic surface cavities, with strong molecular bonds. But also sometimes, for no apparent reason, all the bone around a titanium implant will just start dying and resorbing. It's rare, but if you get a hip replacement you absolutely need to check on it regularly because if you don't you'll lose use of the leg completely (and quickly, and permanently).
In and around the heart is one of the most challenging places to implant things, aside from maybe the brain. Any moving part of the body will constantly stress any mechanical part, and build up scar tissue around and rubbing spots. The only reason the brain is worse is because its fragile and changes size significantly when you sleep.
Recently we started using leadless pacemakers. Even before that pacemakers were continually getting smaller, and smaller pacemakers are less irritating and experience less stress and movement. Even if that weren't true, it would still be worth checking in on pacemakers, because they're doing incredibly hard jobs and if they fail people can die faster than they can get to a hospital.
EDIT: oh, and heart disease is the #1 cause of death in the US, while heart surgery is one of the most difficult specialties to get in to. They are absolutely never short on patients, lol.
It sounds like you have quite a bit of knowledge on the subject. I had to get a pacemaker a couple years ago, and am an embedded engineer. I hope to live another 50 years at least, so this is an interesting subject for me.
Maybe my cardiologist is just trying to make me feel good, but he says my leads will likely last 30-50 years. Intuitively that seems unlikely, but we'll see. It's got to be one of the most engineered cables in existence.
The leadless pacemakers are indeed a technical marvel, but they aren't yet nearly as feature packed as shoulder implanted devices. They'll keep your heart from stopping if your nerves are flaky from time to time, but they don't have the energy storage to do much more than that. Mine monitors every single beat my heart takes, and automatically reports issues to my doctor via BLE. (Is bluetooth more or less scary than radioactive isotopes mounted in your body?)
For about 8 months, my AV nerves were completely broken, and the pacemaker paced my ventricles 100% of the time. It was a nearly perfect drop-in replacement for the failed nerves. A leadless pacemaker wouldn't have had nearly the same performance. My nerves eventually started mostly working again, and now I'm on track to have a battery life pushing 15 years.
It would of course be great for the technology to advance even more over the next decade. Since my nerves mostly healed, a leadless device with a 30+ year battery life would be a nice replacement. With a shorter battery life, I don't really want to be collecting them in my heart (they don't plan to remove leadless pacemakers when they die.) I'm hoping by the time my current device is worn out, it will have logged enough telemetry for me to convince my cardiologist that I don't need a pacemaker at all, though.
> Maybe my cardiologist is just trying to make me feel good, but he says my leads will likely last 30-50 years. Intuitively that seems unlikely, but we'll see. It's got to be one of the most engineered cables in existence.
One of my favorite learnings in school was about the "Endurance limit".
Some materials, like aluminum, will eventually fail under cyclic loading even at tiny, tiny loads. This was a big problem when they built the first passenger jets. Other materials, like steel, have a threshold at which they can be cycled indefinitely without issue.
For something like a pacemaker, I like to imagine they dialed the materials and forces to be within such a threshold so you can keep on ticking!
Re passenger jets - I imagine you are thinking of the Comet 1? That was a more complex failure than is generally known. In brief, they did know about fatigue life at the time, and had ways of retiring aircraft before it was an issue (safe-life design, apparently introduced in the 19C for steam engines despite their being iron and steel). Ok, now you will be thinking "square windows, stress concentrators". Almost all pressurised aircraft use windows with angled corners in the cockpit. There isn't an intrinsic bar to square windows, and in fact the original design would probably have been ok. That used glued installation, avoiding stress concentrators. However a production engineer changed the design to use riveted installation, which caused the well-known problem with hull failure. Still, that would have been discovered if DH had not managed to resist government pressure to do fatigue testing on the pressure hull (because they were racing Boeing to be first to market, and fatigue testing takes time). They actually had the apparatus for repeatedly pressurising the hull in a bath, but only used it for testing static pressure.
If you have complete AV block, a leadless pacemaker is less good than one with multiple leads, since it allows pacing multiple chambers and maintaining synchrony between A and V.
That's neat, although the left channel of my wireless earbuds drop out like 2% of the time!
What I want is a shoulder implanted pacemaker that's significantly smaller, with a quarter of the primary battery capacity, and an inductively charged supercap that can store enough charge to run at least week between charges.
Lol. I've certainly already made the joke that embedded systems are dear to my heart. I'd consider working a few years at a place like Medtronic just to see what I can contribute, but on the other hand I hear there's roughly a 2:1 ratio between requirements and lines of code.
Going through airport security is fun just because the TSA agents overreact as if the metal detector is going to kill me.
/u/sgtnoodle has accepted a great job with MedTronic, little does he know, that as a QA process embedded engineer, his duties require him to monitor various labs - including the PENTEST/AGGRESSIVE attack lab... but the anechoic chamber contract was low bid - and has leaks...
As he walks by the lab, checking his tablet for his various checklists... there is a leak.
A deadly leak... As he rounds Corridor-4A toward his desk, the leak hits him.
As a Class-I Mk2 Embedded engineer, he was susceptible to the RF attacks...
We only found him after the alarm sounded that he badged through Door X1A, but never made it to Door TR3B where his lab was...
Cardiac failure due to failed electro-stim documented as cause of termination of employment.
You are getting downvoted for the conspiracy theory aspect of your post and for throwing shade on a guy with the pacemaker. If you care about being liked, say likeable things.
It's not. It's a full diagnostic interface. Someone with the right software and my serial number could reconfigure it from across the room.
BLE replaces the previous diagnostic interface, which was some form of near-field. You had to have a puck resting within a few inches, going to a several decade old toughbook. My device supports both. It's just in the last couple years that UCLA got the BLE equipment, and sometimes a doctor will whip out the old gear if they feel more confident with it.
When I had the pacemaker first implanted, there was a reliability problem they had to do a second operation to fix it. The pacemaker failed to "capture" my ventricle a few times when it should have. It turned out to be a loose lead connection, but the device's impedance diagnostics didn't make the issue immediately obvious. My overall case was weird enough that UCLA did a case study about it, so for the revision procedure they had a vendor rep in the room to help out just in case. She was holding a tablet and pushing buttons that would make my heart temporarily stop.
Now my AV nerves mostly work again, so the pacemaker can't stop my heart if it wanted to. It can only increase my heart rate, and report unusual patterns to my doctor. Also, if someone did somehow mess with it, holding a strong magnet near it will force it into safe mode.
That's fascinating, and very unfortunate how lax the security likely is for an organ keeping you alive.
You would think if you can detect a strong magnet, you could use that to turn the wireless on and off... Like how holding a power button on a phone turns it off, but holding longer can do a factory reset or what have you.
An interesting thought would be to have a nano-lead down the arterials to the wrist, where an external telemetry relay-watch could read the signals, and have the BLE device top dermal. (apple watch)
eliminating RF/BLE bullshit from talking to the pacemaker.
I don't think my particular pacemaker has the necessary circuitry to generate more than 5V, in pulses less than a few milliseconds. The voltage doesn't really matter much to the muscle.
If you got in you could probably put the leads into single-ended mode (so that there's more current path to cause mayhem) and pace my atrium and ventricles at 210bpm, and effectively give me a seizure. I can't imagine it would kill me before an EMS arrived with a magnet?
Perhaps a more nuanced attack would be to somehow use all the configuration parameters to intentionally bias the pulses so that there's net charge going into the muscle. Over a long time that would cause tissue damage.
If someone wanted to kill me overtly, a gun would be less work. A pacemaker malfunction that bad would be thoroughly investigated, and would be fixed in new devices within a year or two.
If they were able to cause the pacemaker to fire when they wanted they could time it during the repolarization, which could possibly cause a fatal arrhythmia even in a heart that doesn't need a pacemaker. It's called R-on-T phenomenon and it's usually caused by malfunctioning pacemakers.
I doubt you could do that through configuration changes alone, simply because of how defensive the firmware would be about that exact scenario. You'd probably have to resort to code exploits on top of simply gaining access. Even then, there's probably a rudimentary interlock at the silicon level.
The crazy thing was that this was when there was a lot of talk about Dick Cheney and how he was vuln to this attack -- and there was a lot of spec around if barnaby was silenced because it was the older, Cheney-esque politicians that could be taken out by this vector...
Perhaps, he got the 'reverse bounty' on this bug...
It's a weird argument, though, that we should be checking in on the state of the patient & these devices, but we don't do it unless we have the additional problem of needing to replace a battery.
Modern devices provide a wealth of telemetry completely autonomously. My pacemaker talks at least daily to a UFO shaped brick on my night stand via BLE. The brick has an integrated cell modem, and was given to me pre-configured. It has a bright green light (that turns off in the dark) to show that it's functional. It has a single button I have never pressed, for if I think something notable enough happened that my doctor's office needs to be sent a report sooner than every 90 days or so.
> 315 million times. That's an order of magnitude higher than we typically test fatigue resistance
Nah, it's not that bad. Decent mechanical keyboard switch is specified for 100 million clicks [1, or google for "switch million actuations"]. Surely good engineering can eek out another order of magnitude. Not to mention - pacemaker leads ("wires"), the only part that bends, have way less stress on them (= larger bend radius) compared to a keyboard switch. Oh, and technology of multi-strand wire for redundancy is a very well established and understood one.
You're not counting failure rate over time. How many people actually click a key 100M clicks? What does the bathtub curve look like? What's the failure rates at 1,10,100,200M clicks?
I'm going to assume those failure numbers are far higher than you'd want for something keeping you alive.
I've had Cherry switches fail right as the keyboard's warranty was up. The switch feels soft after wearing out, it gets dust in it and starts double typing, etc. Pacemakers need to be 100% reliable, not 99.9%.
Indeed, the keyboard switch people have to produce a device that's manufacturable at scale for pennies per unit, and can be fitted in unforgiving environments by the untrained.
How is that comparable to a pacemaker in any way? They aren't made for a similar scale, price, or 'environment', and would only be installed/serviced/dealt with at all by anyone aside from highly trained specialists.
Intentions aside, I read it as a very narrow comparison of the relative durability - I'm guessing they weren't trying to devalue pacemaker engineering.
I have an ICD, and have had to have two lead revisions, once when the lead failed to implant, and the second when it cracked. My resting pulse is 100bpm, and the device overpaces me if I exceed 140bpm (unless having sex, when it kicks in at 220bpm. Is this so I'll die happy?). So in ten years my leads cop at least 500 million bends. Since my device does cardioversion and defibrillation there's no way a wireless implant in the atrium and ventricle will work.
The doctors keep quoting figures of how reliable this tech is, but I've had 3 procedures due to device failure in the last 5 years.
All of this sounds fine in theory as an explanation but was material fatigue actually why the technology was abandoned? Like you say, those complications are rare and the section that was quoted by the other commenter seems to imply that the opportunity to upgrade the patient's hardware was the real motivator (since obviously the opportunity to swap batteries wasn't a factor for the nuclear variant). It seems more like a question of if regular upgrades produce results significant enough to justify opening the patient up again after implanaing what's currently state of the art. Or is surgery obligatory in either case?
> EDIT: oh, and heart disease is the #1 cause of death in the US, while heart surgery is one of the most difficult specialties to get in to. They are absolutely never short on patients, lol.
This is still relevant to his concern, but from the other end. They might be making the labor artificially scarce to increase pay.
> This is still relevant to his concern, but from the other end. They might be making the labor artificially scarce to increase pay.
This is very much true. I find that a lot of people in tech seem to put healthcare on a pedestal and believe that the professionalisation and gatekeeping of the industry create a better outcome than other engineering fields. This is very much untrue, the healthcare field is in need of massive disruption and lobbying to increase labor supply. You are being downvoted because a lot of tech people here hate to imagine that healthcare at the highest level is still subject to market forces like everything else. Medical training is being severely gatekept and hindered via the current apprenticeship/residency system. After all, we call the worst medical student, doctor. If you want to improve healthcare, tie medical school admission to the MCAT score, and only the MCAT score. You are not going to get better doctors just because candidates spend their summers building houses in some impoverished third world country.
I live near Boston which is known for its medical centers, so this might skew things somewhat, but it seems like every graduate I know is going into medicine of some form (surgery, anesthesia, nursing, surgical tech, hospice, etc. etc.)
I heard consistently that residency slots are extremely competitive and a lot of qualified candidates get passed over. The more I learn about the process the more insane it seems.
From the student perspective you go from paying to work one day and spending most your time working cases with zero relevance to your actual specialty, to raking in several hundred thousand a year.
It also seems like hospital systems seem to spend more than half their capacity either dealing with patients that don’t need to be there but there’s literally no place to send them, or patients that are too far gone and untreatable but there’s literally no place to send them.
Healthcare is like a Gordian knot of terrible policies cemented into place by trillions of dollars of government spending.
We turn away beyond capable people, it’s just that we have decided to drastically reduce the number of doctors per capita by artificially limiting the number of medical schools.
700k people per year in the US die from heart disease. There are ~18k surgeons (of all kinds) in the US. So even if 10% of them were cardiac surgeons, each surgeon has one person dying per day to worry about. They're busy.
Heart surgeries often happen on actively beating hearts. Tiny mistakes mean death. Infections mean death. Its a muscle which never gets rest, the majority of people in the US have clogged arteries and high blood pressure by the time they die.
Theres no artificial shortage. Heart surgery is really hard. Its the third hardest kind of surgery, right behind brains and rockets.
Brain neurons going into sleep mode eject some of the cell contents and shrink, which apparently also helps flush waste because the cerebrospinal fluid can flow better.
There’s not a single cardiac surgeon in the world who thinks he’s gonna get rich with once-every-10-years follow up appointments. We produce enough new patients to keep them all sufficiently busy.
A private surgery business that specialised in pacemakers would surely care, because those 10yr repeat customers would be part of the valuation (valued like SaaS with long duration and high churn?). That would matter to a surgeon with an ownership stake on retirement.
I agree that a surgeon at a general hospital probably wouldn’t care (little financial incentive).
Private practice is quickly going extinct in the US. It's generally not an option for US residency and fellowship graduates these days unless they are in one of the specialties that has cash payors (plastics, dermatology, orthopedics, a small number of "concierge" primary care docs and psychiatrists that cater to rich patients, and a small number of ophthalmology practices that carved out a good Lasik business).
The vast majority of pacemakers are placed by cardiologists with an additional two years of training in electrophysiology (not by cardiothoracic surgeons, who prefer to do complicated open heart surgeries and generally find things like pacemakers boring).
Contrary to the conspiratorial thinking all over this thread, medical society guidelines have scaled back the indications for putting in pacemakers time and time again, so the market has shrunk. Electrophysiologists have to make up for the lost pacemaker volume by doing newer procedures (ablations) that reimburse less per hour of work. Even then, the volume at a lot of shops isn't enough to merit full time work. A lot of graduating electrophysiologists have to take mixed electrophysiology/general cardiology jobs where less than 50% of the work is electrophysiology.
All that is to say, no, pacemakers are not a money making scheme. While there is decent money to be made, it's a shrinking market and those who got obscenely rich putting in pacemakers in the 80s and 90s have mostly already retired.
Yeah I how everyone who has a body.... a thing that is naturally subjected to ageing and death... has it in for surgeons when they are professionals at trying to reduce the impact of this inevitability. Its like we think our body is a car and we deserve a warantee then sue the surgeon when the surgery doesn't have any effect.
A friend had one of these units that extended his life for over a decade. He had it upgraded at least once, and the programing updated several times, and noted improvements each time (although he never got the one feature he really wanted [0]). So active maintenance is definitely not spurious or mercenary but is genuinely useful.
[0] When the pacemaker detected a problematic arrhythmia it would give a couple of defibrillation shocks just like the paddles but right on the heart muscle. He said this felt like getting kicked in the chest by a horse and came completely out of the blue with zero warning. So it could be quite disruptive. He wanted a feature where it would tingle or beep or something just a few seconds ahead of time so he could mentally prepare; apparently the second one that was expected was a lot less traumatic. Anyway, the docs thought it was a good idea, and passed it up, but it never happened before he passed.
> He wanted a feature where it would tingle or beep or something just a few seconds ahead of time so he could mentally prepare; apparently the second one that was expected was a lot less traumatic.
reminds me of the pre-safe sound prior to collision
I’m not clear on what he was supposed to do in response to this. Is it a situation where if he were to sit down and relax he could resolve the arrhythmia? Or is this a notification mechanisms that he can then alert his doctors?
(My question is why was this designed to be an extreme “notification “)?
He just wanted some kind of warning to get himself mentally prepared or braced for the kick - maybe take a quick breath, pull out of the way a tool he's using, whatever, or just reduce the surprise factor. As he said, the second one that he knew was coming was not such a big deal. It was definitely not to try to resolve it, that was up to the pacemaker/defib.
My Dad was diagnosed with a fatal lung illness and was given three years to live. He made it to ten years the last six months were rough. But I can't imagine if he had died after the predicted three years.
I see people Dad's age or older driving and walking around and I find it amazing how older people are alive. Elderly people are amazing as people and for their knowledge.
Love every day you and your family are here and healthy!
If battery life doesn't improve much, I don't die prematurely, and I continue to materially benefit from having an implant, I personally could be realistically looking at 3 replacement devices and at least one lead replacement over the years. In the unlikely event that I suffer from ventricle enlargement long term, I'd need two more leads installed as well.
Yup, there's definitely some patients that would benefit from a nuclear battery.
> I personally could be realistically looking at 3 replacement devices and at least one lead replacement over the years. In the unlikely event that I suffer from ventricle enlargement long term, I'd need two more leads installed as well.
This is the point I'm making, though: realistically, you have a high chance of needing 2 additional procedures for non-battery reasons, which are likely good times to replace the device, too.
> cynically read this as "we needed to get more money out of these patients"
Unfortunately in the OECD I think its possie for an American to read it this way due to the unusual health system. Don't get me wrong... things are changing elsewhere too... it used to be a great shame to go sue a surgeon for anything but reckless intentional negligence... after all we all have bodies that age and decay and the surgeon is provided freely as a public service and their profession is to try as best and compassionately as they can with their training they recieved freely to delay or prevent the suffering inevitable from life... now people sue here for like an orthopetic surgury that simply didn't produce any result ... we are becoming more like america it is sad.
Medical professionals worry a lot about "compliance". It would not be unusual for a doctor to unironically believe that "leverage" like this—forcing the patient to come in for a check-up instead of letting them make their own decisions—actually benefits the patient. So it's not necessarily about money, but that's not imo saying it's much better.
I cynically read this as "we needed to get more money out of these patients"