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Increased heartrate / medical

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Apr 21, 2003
Hi All

Posted something last week, cannot find the thread, but was asking advice on a sudden and very rapid rise in heartrate during an easy dive which was extremely disturbing.

Found out today what the cause was, a common problem according to a navy diver, it is called cartoid sinus reflex ( Spelling ??)

In short, it occurs when a wetsuit is too resrictive in the neck ( Cartiod) area. This effects blood supply to the brain, and can be a gradual process, but suddenly, the brain will detect a problem...and relay a fast message to the heart, if effect, the message goes something like.." hey heart, I'm no longer getting any good blood up here, start pumping dude, otherwise this guys is in shit....!!"

In an instant, the heart rate, with no warning or obvious reasons, kicks up to near 200 BPM, your chest and throat feel like they are going to bust out of your suit.
Causes anxiety obviously, but there we have it, Cartoid sinus reflex caused by a wetsuit too small / restictive in the neck area.

Sorry about the long winded post, but this caused me big stress, and was quite chuffed to find such a simple explanation. Maybe will help someone else one day ??

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Reactions: Pezman and Adrian
Interesting post Jeff, I'm sure that it will help others - it seems unlikely that with tight suits it doesn't happen to more people than we think.

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Reactions: donmoore
Hi Jeff,
I think here is a confusion. The Carotid Sinus Reflex, produces Bradycardia (slow heart rate), when it's really strong can cause even a Black-Out. When you use a tighth suit, tie, whatever, it is interpreted as if you have high arterial pressure and the brain orders the heart to slow down to keep a normal cardiac output.
I don't know what did you feel in that dive. But an increase in heart rate is possible in hypoxia, electrolite disbalance, dehydration, medications or medical problems.
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Reactions: donmoore
My doc could not explain to me why I experienced the huge increase in heart rates only during freediving, and my concern was that it had something to do with apnea. The confusing part is that it did not occur on every dive, obviously depended on the amount of 'soap' in my neck area, and also according tp the 'expert', your cartoid artery can be more swollen on some days, depending on temperature, exertion, etc.
I have always suspected that my suit was too tight, so my first mission now is to get the neck section re-cut and 'looser', even if it means losing a bit of warmth in that area.

Hi Frank

A diver explained it very differently to me. Said it as I explained it above, and told me of a few cases that were very similar to mine.

I can assure you I had no hypoxia or dehydration issues, was on no medication, and my BP, etc is all 100 percent.
Hi Frank

Managed to get hold of a diving medical journal yesterday, and found the section of carotid sinus reflex, and you are 100 percent correct, it should slow my heart-rate down, not increase it !! So there I was again, back to square one, still non the wiser except having been given a clear bill of health following a check up.

Then today, was chatting to a climbing buddy, mentioned it to him, and he immeaditely asked if i was hungry at the time.
I did the dive after 12:20 pm, and had eaten NOTHING all day. During the long walk to the entry point, I had realised how hungry / thirsty I'd felt and still thought that it was stupid to be diving like this.

He told me he had experiened the same thing during snorkelling, where your body is running low on 'gas' due to lack of food, and you then add extra stress with breathhold, causing the exertion and subsequent increase in heartrate ?? Would this make sense.

Seems more likely considering my hunger at the time.

Hi Frank

Managed to get hold of a diving medical journal yesterday, and found the section of carotid sinus reflex, and you are 100 percent correct, it should slow my heart-rate down, not increase it !!

I should hope so! He's an internist and sub-specializes in pulmonology, if I'm not mistaken. He's one of DB's greatest assets. You should see some of he threads that evolve when he, Eric F. and Bill get deep into a topic :):cool:.
Hi Jeff,
Sorry for the delay to write back, but I was in a cold, constant ballast freediving weekend. Well now you know about the reflex.
You said you were thirsty, so it implies some kind of dehydration, and that could explain all. But my advice is that you get a check-up from a cardiologist (better if he knows about diving medicine) to rule out a problem. My brother also had that problems in static apnea, and I rule out any disease, just paying attention to hydration and nutritions (specially pottasium) before apneas the problem was solved.
Pezman, thanks for your words. And, yes, you are not mistaken.
Safe freedives
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