Pacemaker impact on freediving

[cdavis]

A long time diving buddy of mine recently had a pacemaker put in. His doc didn't tell him it would implode at 100 ft (By the way, that can kill you). He got another one. Now we are a little wary of his non-freediving docs and wonder what else might be out there to bite him. For instance, the pacemaker doesn't allow his heart rate to fall below 60. On a long deeper dive, his heart rate would normally fall into the 30s or thereabouts when his DR kicks in good. What happens to his blood pressure if his heart only needs to beat 35 bpm and is still kicking along at 60? Does it overpower his normal DR? If so, will it shorten his dives? make deeper longer dives unsafe? If not, does his blood pressure skyrocket?

Anything else to watch out for?

We would sure appreciate some input from medically educated freedivers.

Connor

 

[Bill McIntyre]

I've had pacemakers since 1984 with no problems. My resting rate is 38-39, so my pacemaker is set at 35 and only kicks in when my rate drops below that.

When I've had replacements, new docs have wanted to set them over 35, but I insist. The last one lasted 12 years since it doesn't fire very often.

I don't think there would be any problems with blood pressure, but maybe it might shorten his dives. I've often wondered if mine hurts my dives.

 

[cdavis]

Good to know Bill; I'll pass that along, especially the part about setting the rate lower.

Anybody else out there with a pacemaker?

Still hope some physician types will chime in.

Connor

 

[Bill McIntyre]

Connor,

Obviously I don't know why your friend needed the pacemaker in the first place, and he may not be like me. Also, while you mentioned what his rate drops to while diving, you didn't say what his resting rate is before a dive. I have no idea what my heart rate dropped to while diving, but my resting rate just sitting here is around 38 to 40, so that is why the pacemaker rate of 35 was chosen.

I suppose I should say why I got the pacemaker just in case our cases are similar. For maybe ten years before getting it, when I had what I call a hard-to-get-up burp, I would get faint, have tunnel vision, maybe get grey vision, and sometimes go totally black for a few seconds. These are all classic symptoms of a lack of oxygen to the brain, and I was familiar with them as a jet pilot making high-G turns. It turned out that putting pressure on my vagus nerve, which seems to run from the brain to the asshole, was causing my heart to pause. I was still flying jets most of that time, but I never bothered to mention the symptoms during my annual flight physical for fear the flight surgeon might get excited about it, and in fact I never had symptoms during flight. Much later, a cardiologist agreed with me that the reason it never happened in flight was probably that I flew single-piloted jets and wore a mask providing 100% oxygen from takeoff to landing. That probably kept my blood-oxygen level high enough to tide me over the pauses in heart beat.

But anyway, after retiring from the Marine Corp, I finally fainted and woke up on the floor. I decided that this might not be a good thing if it happened on the freeway, so I fessed up and went to a cardiologist and he finally figured out what was going on. I won't bore you with the details of how that diagnosis was finally made since its probably not relevant, and your friend has already been diagnosed anyway.

I hope this will prove helpful to your friend. I'll be glad to answer any other questions that I can.

 

[fpernett]

I think Bill gave a real good advice.

First, Why your friend need a pacemaker?. If he has a 3 degree AV block, isn't wise to set the pacemaker below 50.
Second, as you said, low heart rate is part of DR, and in that way the Cardiac Output (CO) goes down also, keeping oxygen consumption under basal rate. If you're unable to slow your HR, CO will keep high, and that probably ruins all your DR. Diving without it, make you prone to SWB.

If you want, tell your friend to write me directly

 

[cdavis]

Thanks Bill and Frank

I will definitely have him contact you both directly, through a DB pm.

Bill, I'm guessing on his heart rate during a dive. Mine drops into the 30s maybe lower and he is pretty similar to me on other things. I don't fully comprehend why he got the pacemaker, but 60 seems pretty high for a 60 year old in good shape. The best rate for this particular diver is for the doc to work out.

So likely keeping the heart rate artificially high ruins your DR instead of sending blood pressure soaring. That makes sense, but are we sure that is actually what happens? Better that than soaring BP, I think.

Ruining the DR will shorten his dives, give him a C02 hit early, burn more 02 and might well increase any tendency towards B0, his C02 tolerance is pretty good, much better than mine.

Thanks again.

Connor