Cold Water Swimming and Atrial Fibrillation

Salty_PhilSalty_Phil Member
edited May 2014 in General Discussion
Hello and Happy New Year to everyone. Has anyone on this forum experienced or have any knowledge of Atrial Fibrillation linked to cold water immersion. I have been sea swimming for around 4 years and winter swimming for the past two years. In December of this year I went for at my local beach here in Ireland. The water temp in the harbour was reading 6.8 deg C and outside the harbour in the bay it was 7.6 deg C on my digital dipper so it was pretty cold but not arctic conditions by any stretch of the imagination. It didn’t feel too bad and I got in fairly slowly and done the usual couple minutes of head up breaststroke before I started swimming front crawl. I swam for a little under 1k and got out about 15mins later but I couldn’t settle into my stroke/breathing during the swim. I went into the sauna to re-warm and my heart went into cardiac arrhythmia (Atrial Fibrillation). I was admitted to the Coronary Care Unit in the local hospital and my heart stayed in fibrillation for 2 days before reverting back to normal sinus rhythm under medication (luckily as they were due to stop and re-start my heart the next morning which I didn’t like the sound of!). The doctors spent the next two days monitoring me and carrying out tests but all was clear and my heart was found to be healthy with no apparent underlying issues and I have since been pool swimming with no problems.
Has anyone else on the marathon swimmers forum has had experience with A-fib? I’m not sure what caused the A-fib episode this time round as I have winter swum many times and this has never happened before. I’m 39 years old and A-fib is usually an issue for 70 and 80 year olds so I would like to get to the bottom of it if I can. The only thing I can think of that was different with this swim is that I re-warmed in the sauna which I never normally do and I was recovering from a chest infection at the time. I’m not sure if I went into A-fib in the sauna with the sudden temp change or upon entering the sea but it would be good to hear if anyone else has any experience with this. I don’t want have to give up winter swimming but I’m not keen to have a repeat episode. Just not sure if this is a once off or if I’m going to be pre-disposed to A-fib and might have to limit myself to dips in 12 degree plus water temps.




  • DavidDavid Member
    edited January 2014
    Hi Phil

    Sorry to read about your problem with Atrial Fibrillation. Its fascinating to read your account but I guess not so much fun to experience. I am glad you seem to have good health care and the doctors have helped you.
    The Temperature of 6.8 deg C is quite cold! I say quite with a smile on my face because I am currently struggling to maintain my training because the pool and sea temperatures are hovering at 28 deg C. I was wishing for colder water yesterday and after an hour of fast sets I was dehydrated! I had to drink two liters of water before I started to feel normal again. I dream of swimming in 12 to 18 deg C water :)
    I am sorry I cant help you further. Have you researched it using Google? There's so much out there I am sure someone else has the answer you need. For a start you might like to read the following.

    Good luck
  • It's the sauna.... while we in SF adore our sauna , after 35 some years of OWS, I am finding anecdotal ( ie personal) evidence that that lovely sauna is what #1- leads people to think they can stay in longer than they would normally because* there's a sauna I'll warm up there" and #2- that rewarming too quickly kicks them into fainting or in your case atriall fib.
    I am no expert, nor am I a doctor but I bet if you had just shivered you'd be fine.
    Again, anecdotal.. I know there is research out there on the cold and the heart but not so much on the rewarming process and the heart.

    Looking for the next big thing.. ... @suzieswimcoach

  • Thanks for the comments. I had a good read around on google and a chest infection can be a trigger for a fib but there is very little on the net about the cold water or re-warming and a fib. I'm off to the heart specialist in Galway tomorrow for my last round of tests and if I get the all clear and they can't find any underlying condition i'll be putting it down to a combination of the chest infection and re-warming in the sauna.
    Had the heart rate up in the 170's during my pool sesh this morning with no problems so hopefully all is okay and its just a one off.
  • molly1205molly1205 Lincoln, NebraskaMember
    What a scare you had! I think Suzie's response makes sense - though I'm no doctor. Hopefully your specialist will give you the all clear to get back to swimming and you can enjoy the cold water, just with a slower rewarming process afterward. Let us know how things go!

    Molly Nance, Lincoln, Nebraska

  • DanSimonelliDanSimonelli San Diego CASenior Member
    I agree with Suzie, anecdotally ;-)

    I think it's the quick rewarming, vasodilation of the blood vessels outside the core, cooling the blood as it circulates through the cold extremities and then back to the heart!

    I don't like jumping in a jacuzzi right after...I think it's better to bundle up, walk around and shiver...that seems to do the trick for me, anecdotally :-)
  • emkhowleyemkhowley Boston, MACharter Member
    Hi @salty_phil Sorry to hear about your bad episode. That is indeed terrifying, and I hope that the recovery is going well and that you never have to deal with that again.

    I am not a doctor, nor do I play one on TV, but I am an ice swimmer who dabbles in hypothermia from time to time, and I have just recently completed research for an article I've written about the condition. In my research I turned up some valuable resources that could help explain what happened with you. Based on this research, I would hazard a guess that you suffered the consequences of afterdrop, which was exacerbated by the sauna. I'm basing this theory on a paper I found online called "THERMAL AND CARDIOVASCULAR CHANGES DURING THREE METHODS OF RESUSCITATION FROM MILD HYPOTHERMIA" by J.S. Hayward, J.D. Eckers and D. Kemna. Link:

    In the paper, the authors test three methods of rearming after inducing hypothermia in test subjects. Patients who were submerged in a warm bath were most susceptible to severe afterdrop, whereas patients who were left to "shiver it out" while bundled in dry blankets had a less-severe afterdrop experience. Patients who were bundled in dry blankets and allowed to inhale warmed air fared the best of the bunch. It's my understanding that the conclusion to be drawn from this is to avoid exposure to extreme heat after becoming even mildly hypothermic, as that facilitates the exchange between warm core blood with cold blood in the extremities and at the skin's surface, which can shock the heart and cause problems. This report has a really dramatic graph (see Figure 4) that shows how the experiment went down and really drove home to me how important it is to exercise extreme care during the rewarming process.

    A similar study published in 2003 excluded the bath but also compared rewarming across three different methods:

    Another good resource I found was a slim book at the local library titled, "Hypothermia Frostbite and Other Cold Injuries: Prevention, recognition, and prehospital treatment" by
    James A Wilkerson, M.D., Editor; Cameron C Bangs, M.D.; and John S. Hayward, Ph.D.
    It was published by the Mountaineers in 1986.

    I also found this site and its extensive bibliography interesting and useful:

    Good luck and STAY SAFE out there everyone!

    Stop me if you've heard this one...
    A grasshopper walks into a bar...

  • excellent response @emkhowley . Fascinating stuff for a cold water swimmer. What would you say are the risks of entering cold water when your body is very warm, say, from running? Does this pose a similar risk? Or is it a different process?
  • I LOVE this Elaine... Going to print and post at DC.

    Looking for the next big thing.. ... @suzieswimcoach

  • gregocgregoc Charter Member
    edited January 2014
    I am not a doctor, but I play one on the MSF.

    @gnome4766, the short answer to your question is that it is different. The longer answer from Wikki: "In humans, cold shock response is perhaps the most common cause of death from immersion in very cold water, such as by falling through thin ice. The cold water can cause heart attack due to vasoconstriction, the heart has to work harder to pump the same volume of blood throughout the body. For people with heart disease, this additional workload can cause the heart to go into arrest."

    @Salty_Phil, I recently read a paper that argued that the core afterdrop was not due to cold blood circulating back to the heart, but to a gradient conduction through the tissue.

    Also, it takes temperatures dropping from 35 degrees F (already very hypothermic) down towards 28 degrees F to induce Atrial Fibrillation in a normal heart. You would have to reach core temps that are life threatening before your heart went into AF and I am sure you didn't reach those temps.

    A mild core afterdrop can cause AF if you have underlying heart problems or if your heart was already under stress (such as the chest infection you read about.

    I hope everything checks out clean.
  • Gregoc and emkhowley thanks for your posts really interesting stuff. I went down to the A-fib specialist on Friday thinking I was going to get the all clear but unfortunately it didn't turn out that way. Turns out I have an underlying heart condition which is present in about 2% of the population. I have additional connections at the back of the heart which can cause the normal electrical currents that maintain the heart in sinus rhythm to divert putting the heart into an A-Fib rhythm.

    I quizzed him in relation to cold water swimming/chest infection etc as causing this and his stated that it is not possible to put a 'normal' heart into A-fib under any of these conditions. Either the extra connective tissue is present or its not - its just something that you are born with.

    Good news is though that it's not immediately life threatening and at my age its pretty treatable with a surgical ablation procedure that closes off the additional pathways by forming a scar tissue at their ends.

    What was really interesting though is that in his opinion the A-Fib event is unlikely to have been caused either by entering into the cold water or by re-warming in the sauna. He put it down to the chest infection but believed it would have surfaced eventually anyway. Alcohol, smoking and certain infections seem to be the most common trigger but it can happen just as easily in your sleep as during exercise.

    Still seems like too much of a coincidence to me though. How many cases of patients with a-fib who swim semi-naked in 7 degree C water and re-warm in a sauna straight after would a specialist in Ireland see each year? My guess is none so I'm going to avoid the sauna and sub 10 degree water until I get the op. I guess its the pool for me until May - I just cant face putting a wetsuit on.

    Thanks for the comments.
  • loneswimmerloneswimmer IrelandCharter Member
    @Salty_Phil, that's, well I'm going with good news, insomuch as you have a definite course of treatment and therefore the potential to keep swimming. I think it's been a potentially invaluable discussion for others, and thanks for raising it.

    At 2% possibility, that means we may have sixteen to eighteen forum members who could unknowingly have this condition.

    Best of luck with the op!

  • danswimsdanswims Portland, ORMember
    A wealth of information on atrial fibrillation here, this post and others on Dr. John's blog.

    Including some evidence that endurance athletes may have an increased risk.
  • danswimsdanswims Portland, ORMember

    Bump with a link to a book on excessive exercise leading to heart problems, written by a cardiologist who is also an endurance athlete.

  • I have had Atrial Fibrilation. It developed slowly and intermitantly, but within a year it had developed into a 24/7 problem. The same cause as Salty Phil, electrical pathways short circuiting the natural heart rythmn making the heart beat like a set of bongo drums being played by a six year old. The fix was a hole in the groin, with a cold wire threaded into the various ateries leading into the heart. The freezing caused a scar inside the arteries which diverted the electrical pathways until the natural beat was restored. I understand it took my doc around 50 scars. The fix was immediate and has never re-occured.

    At the time I was around 45, and had stopped open water swimming, about 5 years earlier (having swam the EC twice) and taken up freediving. Freediving was in its infancy. My swimming experience helped me perform well but I was always 'rubbish' at breath hold. In 2002 in Hawaii I swam 156m dynamic apnea (only 15 meters short of the world record held by Herbert Nitsch). In that comp, Herbert managed 144m. What made it unusual was I could only hold my breath for 5 minutes, whilst he could do 9 minutes. Most of the UK freedive team could hold their breath around 7 minutes, but could not get close to my distance.

    We figured, that my inabilty to breath hold (static, at rest) was affected by the heart beating in AF and therefore burning / wasting O2. But when in dynamic effort, raising my heart rate to around 120bpm from 50bpm, the inefficiency of a misfiring heart rate (at low revs) was erased once a proper heart rate was caused by exercise (although still in breath hold). I guess its a shame I couldn't hold my breath for just 10 seconds more, I might have had a world freedive record.

    Anyway, I had to stop freediving for two years whilst waiting for the surgeon to fix my heart. I then returned to open water swimming. And a couple years ago, did my first ice mile. I am now 59.

    It has been over ten years since my operation and I have never had AF since ( I occasionally have stress induced palpitations, which feel similar).

    It would be interesting to see how Phil is, he should have had his fix by now.

  • I haven't tried since. I was forbidden to do it until well after the opp, so it had been two years since I had a max effort at 5 mins. I had decided to start swimming again instead and needed a clean break from competitive freediving in order not to be tempted to restart. I bet I could do better now (after a year or so training and if the hunger returned). But I also had a problem on one of my last deep dives and came out 100% deaf in my good ear. My hearing returned (to a degree) over the following month, but it made the tinitus much louder. Maybe I am too old now . I need to concentrate on swimming for a few more years yet before I run out of sensible time.

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