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> 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.

There are now leadless devices that communicate with each other using RF.

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.

My heart sank when you mentioned a BLE-enabled pacemaker. Has technology gone too far? /s

It sounds like the bluetooth functionality is only there for telemetry.

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.

Being pragmatic, that sounds way worse than just having a little ceramic 2.4ghz antenna and some extra silicon potted into the device!

https://www.dailymail.co.uk/news/article-2379009/Barnaby-Jac...

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Oops - I didnt realize you were same poster from other comment

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 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.

Glad you're doing better since then, though.