I wonder why...
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His was detected by accident during a routine physical. An abnormal heartbeat detected during the physical led to EKG which led to stress test and other tests which led to diagnosis. He actually doesn’t have any symptoms (other than fatigue he’d previously written off that he’s now thinking might be due to this) which they attribute to him being very athletic; I think that’s why they were comfortable making him wait. We have instructions to go to the ER if he starts getting faint, having pains, etc.
If there's no fear of unknown infection, hopefully they have him on high dose Prednisone. If the tissue isn't scarred over yet, those nerves can regrow. Luckily 2 of mine started working again.
The good news, by the way, is that even if those nerves are shot forever, modern pacemakers are really good at replacing them. It's almost flawless. It took my cardiologist a couple weeks to dial mine in because it was a little wonky at first, but it wasn't a big deal; there's dozens of parameters that can be fine tuned. (and it helped that I am an engineer and built my own ECG, because the first week my heart beat was instantaneously alternating between 50 and 100bpm. Sending the dr. a trace of that got me an appointment with him 8AM the next morning!)
Really the only observable downside is that, unlike your nerves, the pacemaker has a programmed upper pulse rate limit. The factory default is something like 155bpm, which works fine for elderly people, but for younger fit people that's pretty low. The cardiologist can crank it up to maybe 190bpm, but they won't want to because it's close to the limit of what the pacemaker can actually do to reliably sequence the heart muscles correctly. This is actually a big deal for usability because, in the case of a straight forward AV block, the sinus node is still working properly and generating your natural atrial pulse rate. The pacemaker is just doing its best to detect the atrial beats and propagating the signal down to the ventricles in place of the damaged nerves. If your natural pulse rate goes up above that programmed limit, the pacemaker can't do anything to slow down the sinus node, and so instead it simply has to start skipping every other ventricle beat. When working out, this means that you could be right below the limit and your heart is beating fine, and then a moment later your heart rate increases slightly above the limit and your ventricles suddenly start beating at half the rate. Doing cardio for 15 minutes and then having your effective heart rate instantaneously drop from 155bpm to 78bpm does not feel pleasant; I'm pretty sure that's the "sudden feeling of impending doom" symptom that gets rattled off in prescription drug commercials. It happened to me several times while exercising and I had to immediately sit or lay down for several minutes and let my body work it out.
After a few months I was able to convince my cardiologist to crank up my limit to 180bpm, but then a week later my nerves luckily started working enough on their own again that it didn't really matter, since a standard pacemaker can't (and shouldn't) prevent the nerves from working naturally. That lead to another interesting quirk, where now any time my heart rate briefly shoots up above 190bpm or do, I get a call from my dr's office a week later (and my insurance probably billed $500) because the pacemaker logged it as a potential tachycardia event and reported it through its automatic telemetry system. I've had three awkward phone calls now where a nurse asked me if I remembered whether I was exercising last week at 11pm or whatever, and I said something like, "well no, that wouldn't make sense because my wife and I were on vacation... Oh, yeah it's probably just a false positive, let's not worry about it."
My husband is getting a leadless pacemaker. Apparently, they don’t have the ability to control the upper pace limit; they only stop the pulse from getting too low. That will be interesting for him, because his heart rate doesn’t get up to a normal pace when he works out. When they did the treadmill stress test, they could only get him up to 75 bpm after 7 minutes of pretty intense cardio. However, they decided to go with the leadless pacemaker because he does a lot of weightlifting and relies heavily on it for mental health, and they’re worried that he would break the leads on a normal pacemaker doing some of the different types of movements. His heart rate got as low as 21 bpm when wearing a Holter monitor, so I think they’re more worried about that. He already experiences the sudden drop in heart rate when he works out. I’ve watched it plummet from 80s to 40s in a matter of a couple of seconds while he was on a stationary bike. He usually just takes a few minutes of rest for it to normalize and is fine after that.
Coincidentally, my lowest measured rate was 21bpm too. That's pretty impressive he could still exercise! That makes me think he could have been living with the total block for many months. I could walk normally, but the week before I got treated I would have blacked out just by jogging more than 30 seconds, and my kidneys were underperforming from the lack of normal flow. My decline was gradual over about 3 months, and I had a similar feeling of unexplained fatigue.
That's an interesting take on the leadless pacemaker. For lack of the atrial lead, it's just going to beat the ventricles unsynchronized. In terms of blood flow it seems like it should be perfectly fine since your husband is a beast. I would wonder about the long term effects on the heart muscles, though. Presumably, his atriums are beating at 2 or 3x the rate of his ventricles at the moment. With the leadless pacemaker, it seems like that wouldn't change much. With the chambers all poorly unsynchronized, the heart works less efficiently as a pump and so has to work harder than otherwise, and as a result can (only potentially) lead to enlargement over time to compensate.
Both with a leadless pacemaker, and a standard two lead one, only the right (for a typical setup) ventricle is getting "captured". The left ventricle beats maybe 100ms later once the bioelectrical signal propagates through the muscle tissue. That bias leads to your ventricles doing an unbalanced amount of work, and can lead to just one chamber enlarging over time. This is stuff that most patients don't need to even know about because someone in their 70s has no practical risk of being impacted by it. Someone that plans on living for a really long time yet, though, should make sure their cardiologist is checking for that sort of thing with an echocardiogram every once in a while. Once again, the good news is that they can always install a fancier pacemaker.
Not trying to imply your husband's cardiologist doesn't know what they're doing or the leadless pacemaker isn't the best solution, I'm just sharing what I learned along the way that I thought was interesting or relevant.