Scuba Diving and Coronary Artery Disease (ADM Article)

Actually I find this article a bit bland. For the following reasons:

1. Dr Ebersole is adamant (conclusion #1) that everyone should be screened/evaluated for heart disease before diving; but on his own statistics the death rate among scuba divers while diving is about the same as among joggers while jogging, so do we want the whole population screened before they jog? Before they walk quickly? Or maybe before they dare get out of bed? Gentle persuasion of the whole population about better eating habits, might save more lives.

2. He is a technical diver, but fails to discuss important questions about how much more risk there is if you're diving technically. Specifically, there is anecdotal evidence that rebreather diving greatly increases the risk of heart attacks (among fit, healthy young men). Is it true? If so, what is the cause (prime suspect in my book: CO2). There are similar questions about diving deep and long, but not so much disquiet on the anecdotal front.

Just my 2 cents.
 
solocavediver said:
Actually I find this article a bit bland. For the following reasons:

1. Dr Ebersole is adamant (conclusion #1) that everyone should be screened/evaluated for heart disease before diving; but on his own statistics the death rate among scuba divers while diving is about the same as among joggers while jogging, so do we want the whole population screened before they jog? Before they walk quickly? Or maybe before they dare get out of bed? Gentle persuasion of the whole population about better eating habits, might save more lives.
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The risk to those you are with at the time of the cardiac event is surely higher underwater than jogging. Your heart attack may precipitate injury to others. Greater risk surely means a higher level of screening is reasonable?
2. He is a technical diver, but fails to discuss important questions about how much more risk there is if you're diving technically. Specifically, there is anecdotal evidence that rebreather diving greatly increases the risk of heart attacks (among fit, healthy young men). Is it true? If so, what is the cause (prime suspect in my book: CO2). There are similar questions about diving deep and long, but not so much disquiet on the anecdotal front.
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If it's only anecdotal there will not be an answer to your question, not a definitive one anyway.
 
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Solocavediver:

I am sorry you found my article "bland". It was free to you, but I am sorry I wasted two minutes of your very valuable time. It is a reprint of an article I published earlier this year in the Journal of Wound Care and Hyperbaric Medicine where the editors and readers actually found it quite helpful. Unfortunately, your feelings were different. The information and recommendations contained in the article mostly came from a Divers Alert Network sponsored symposium entitled the DAN Fatality Conference which was held in Durham, NC several years ago. The faculty who made the recommendations I presented in the article include Simon Mitchell (Chief of Anesthesia at the University of Auckland and a world-renowned technical diver), Alfred Bove (Chief of Cardiology at Temple University and past president of the American College of Cardiology), Dr. Richard Vann and Dr. Petar Denoble of DAN, and several medical school faculty members from the USA. As for me, I am just a lowly interventional cardiologist with 28 years of medical practice and 40 years of diving experience. I was just a participant in the conference, not faculty. I am sorry that you were unable to attend and provide us with your extensive knowledge on the subject so that I could have included it in my article and made it more appealing to you. I am sure the audience would have loved to have heard your research on CO2. Oh, I'm sorry. Those of us in the medical community don't put a lot of stock in "anecdotes". Kind of like something else -- everyone has one.

Yes, I feel everyone should be evaluated for their individual risk of coronary artery disease prior to scuba diving. I also feel this is appropriate for anyone who is beginning any new form of exercise as does the medical community. You will notice I said "evaluated for their individual risk", not tested per se. A large number of people are at low risk and nothing further needs to be done. Only in those with intermediate to high risk should any testing be performed. This is also true if someone came to my office and wanted to start jogging to get into better shape or lose weight. If they were at intermediate to high risk for coronary artery disease, a stress test is a reasonable thing to do before "clearing" them to go out and jog.

I agree completely with your comment about better eating habits which is why I have all of the recommendations in #3. This is not just for divers. It is for everyone. Cardiovascular disease is our number one killer and simple things can be done to reduce (though not eliminate) an individual's risk of developing it such as better diet which can lessen the incidence of hypertension and hypercholesterolemia, stopping smoking, etc.

The reason I did not discuss technical diving and risk of coronary artery disease is that there is simply not enough information to make any recommendations. Technical diving clearly carries more risk than does recreational diving. Are there more cardiac deaths with technical diving than with recreational diving? Probably not, but that may be because there are far more recreational divers than technical divers. Is there a greater risk per dive of cardiac death with technical diving? Again, there is no data to make a definitive statement. Even if the answer is "yes", there are far too many variables to be able to make any strong statements -- older average age of the participants, greater proportion of males, deeper dives, longer dives, different gases, oxygen issues, inert gas issues, CO2,.......

Again, I am sorry you did not enjoy my article. Please feel free to tell all of your friends and colleagues that it was a waste of your time. You will not hurt my feelings at all.
 
I though the article was OK , Douglas. I think you got a bit carried away with your reply to solocavediver, though.

Cheers,
Matt.
 
Thank you Dr Ebersole, I am sorry you had to expend your valuable time and energy in responding to the above comment. Your comments (and excellent article) are appreciated.

Since apparently everyone can have an opinion..... I thought I'd offer mine.

If someone decides to decline the offer of a simple cardiac risk assessment (almost universally on offer by their general practitioner), or ignore the subsequent advice, then goes diving; has a heart attack and dies (the likely outcome to an underwater cardiac event), that's their decision. Fine. I don't have a problem with that.

I just wish they'd spare a thought for their buddies who will feel obliged to render assistance! I have personally attempted to resuscitate someone on a beach. I can confirm that CPR training manikins in a classroom are markedly easier to ventilate (with their noted absence of vomit, facial hair and abdominal obesity) and chest compressions aren't easy on soft, sloping sand. It was not pleasant for any of us involved (least of all the poor soul's wife who looked on) - even though most of the attendants happened to be medically trained, including myself. Whilst I obviously didn't hesitate to help out, I rapidly realised that resuscitation outside of a hospital setting was a totally different scenario to anything I had trained for.

My somewhat selfish bottom line: I would rather enjoy my holiday than be rendering futile first aid for a potentially preventable event.

Of course, if one dives solo, I guess none of this is an issue.

Deralie
 
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Deraile,

You are right that people need to take an increased level of personal responsibility, but part of that resides with people like Doug providing robust (and sometimes obvious) evidence which allows organisations and individuals to be properly informed. When divers were free to do what they wanted and self-trained, the risk was solely with them. Now with the vast number of training organisations and dive centres, there is a burden of proof to show they did what they could to reduce the risk to a manageable/acceptable level. (A level which is not defined by the way!!)

The following incidents were reported to me:

1. Diver surfaces after a 30m/20min dive coughing, his buddy surfaces immediately shouting for O2 and to get the diver on the surface, but not to worry, it isn't a diving issue. Diver exhibits cyanosis, on board, on O2, skipper calls 'Mayday', diver evacuated by helicopter. Skipper heads home once everyone on board. One of other divers obviously distraught. Skipper asks why. Transpires that he had been told not to dive as he had recently (4-6 weeks prior) had heart surgery and was on anti-coagulatants. At 6m he had a coughing fit, which they believe caused bleeding in the lungs. Diver survived.

2. Diver enters water with buddy. Starts descent, has issues, back on surface, asks for assistance, then goes unconscious. Recovered onto boat. Evacuated by RNLI. Dies later. Transpires has lied on medical form about his health, has history of cardiac issues and has stents. Buddy and skipper very pissed off as neither knew about this.

There is a limit to what can be done with regards to cardiac screening without impacting on the viability of the sport. Most hyperbaric doctors recognise that more should/could be done, but the majority also don't know of an effective way of doing it. In the UK ScotSAC stopped doing diving medicals, relying on self-declaration forms as this had a similar level of detection as medical screening with a GP or even an HSE level medical.

At some point divers have to take responsibility that they are putting themselves in a risky situation. But when we don't know the diving demographic, the types of diving they do, the exposures they place themselves in, it is difficult to determine the delta in health issues from the general public.

Interesting point about diving solo, you still have a family and presume you have friends? Wouldn't they miss you? That doesn't mean have zero risk exposure, but you have to determine what you find acceptable (or your family love you so much, what they determine acceptable if you want to keep them happy ;) ).

Regards
 
Hi Guys. My concluding comments on this one:

silentbob questions: "The risk to those you are with at the time of the cardiac event is surely higher underwater than jogging."

Indeed it will be, but that is taken into account by the nature of the statistics Ebersole presented. He claims annual death rate for joggers while jogging is 13 per 100,000; while annual death rate for divers while diving is 16.4 per 100,000. The general effect that it's more dangerous to have an incident underwater than in air, will be included in that overall figure of 16.4. As will sundry effects the other way, such as blunt force trauma due to violent collision with a truck being much less likely underwater. Add all that stuff up, and it's still "13" for joggers, "16.4" for divers. I'd be interested in how much of the 13 is cardiac. My guess is cardiac diseases will not be the leading cause of death among joggers (being "in third place" for divers), but will account for maybe 10 to 30% of incidents (i.e. in the same ballpark as the 26% figure for cardiac incidents as a cause of death when diving). But I'd be interested in the true figure.

silentbob continues: if it's only anecdotal there will not be an answer to your question, not a definitive one anyway...
Dr Ebersole also adds some similar, rather intemperate remarks about anecdotal evidence.

So sorry guys, but nearly every advance in science starts out life as an anecdote!

Example: the constancy of the velocity of light was not established instantly; initially there was a certain amount of inconclusive evidence and a lot of discussion. Anecdotes, you might say; a good deal of coffee got consumed in the discussion, I'll be bound. Eventually Michelson and Morley confirmed that it was so, and presently Einstein came up with a brilliant, cogent explanation. And thus the special theory of relativity was born.

Example: the dangers of smoking tobacco were first proposed by King James of England (same one as organized the translation that became the "King James" Bible).
He pronounced the then newly imported weed "noxious to the palate, and dangerous to the lungs". And when he said it, there was no conclusive evidence. It was only an anecdote. He was thus lampooned by people like silentbob and Dr Ebersole as the "biggest fool in Christendom"..... However.....

Example: the dangers of asbestos were, IIRC, noted by a classical Roman author ("a lot of the miners in those mines seem to get sick..."). Of course it was only an anecdote then....

Enough said. Right now we have anecdotal evidence of heart disease among rebreather divers. Which, by the nature of the word "anecdote", may be false. Or true.
 
I have a number of issues with the "should be screened" argument. 1. Screened, by whom and what method? I very well know in my own practice that significant diseases can go unnoticed when looked for by conventional i.e. Cheap and readily available methods. Cardiac MRI would certainly pick up more ticking time bombs, but who will foot the bill?
The other even more significant question is that what are you going to those who are screened positive? Confiscate their dive equipment? Placard their photos in every dive centre in the world? Contact their buddies and families and their insurers/qualification agency? As you see from GLOCs reply divers are human and if necessary lie about their health to reach their goal.
Yes, I do wonder who is next up when I go on the usual UK day boat full of rebreather divers. The one dive fatality I have been involved was also due to a cardiac cause, he has run the half-marathon a few weeks before within 1:50...nearly 30 minutes before me. But his right coronary artery was blocked as found out on the post-mortem. Food for thought for the medics on board here.
 
Thanks Gareth, yeah, my family and friends had better miss me (though obviously I'm intending to outlive them all). Suffice to say, I don't solo dive. I'll finish there, lest I unintentionally start a thread on the merits or otherwise of buddies.....:naughty:

iamyourgasman: Like your point about the 'screen positives', of course quite a few of those still wont have an MI regardless of what they do ;-).

All I ask is that my buddies are honest with me about their fitness to dive - as I am with them - so that we call all make informed decisions. I think we owe each other that courtesy. One of my buddies - a passionate and completely addicted diver in his 30's - had a spontaneous pneumothorax (on land, thankfully). He agonized about whether or not to dive again and sought various opinions on what to do - not surprisingly none were favourable. Two dry years later, he has finally made an informed decision not to dive, and sold his gear. He did appreciate the honesty of his dive buddies who varied in our opinions of whether or not we would be comfortable diving with him. (For the record, I said I would: but under a few conditions and ONLY if he stopped smoking!!!)

I guess it's easier where I live for virtually anyone to dive if they so choose - our charter operators tend to take our word for it and I can't imagine any of the operators I know 'banning' someone who was honest with them and was making an informed decision, many people would simply dive off their own boats anyway. Insurance isn't an issue here either, so we're lucky in that respect.

Loving this discussion!

Deralie
 
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Doug, not a criticism but its hardly surprising to hear a cardiologist calling for more testing :naughty:

Some people seem to be calling for everyone to be screened because of the risks they pose to others, surely by that thinking we should be screening every taxi driver, bus driver etc. They pose a far greater risk than a dive buddy.

Surely its about proportionate responses, maybe we start with a few simple questions to screen if people need to go for a test? Mind you, as gasman highlights above there will always be some who slip through the gap.
 
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I didn't say "testing". I said people should be evaluated for their individual risk of coronary artery disease. This was the strong sentiment during the DAN Fatality Conference by the faculty and attendees. All this means is looking at risk factors (age, gender, hypertension, diabetes, smoking, family history,...) and asking about symptoms that may represent underlying coronary artery disease. This is just like a routine office visit with a primary care physician. The only people who should be considered for "testing" (which would generally just be a routine stress test) would be those with multiple cardiac risk factors and/or exertional symptoms suggestive of angina. The presenting symptom in coronary artery disease in about 15% of cases is sudden death. We will never stop people from dying while scuba diving, dying while jogging, dying while playing golf, etc. But if we can find people at moderate to high risk of an event and decrease that risk -- especially if it just involves lifestyle modifications, I think we are serving the population well. Yes, there will be some overweight smokers with poorly controlled diabetes and blood pressure who may end up with stress testing leading to a cath which may lead to stents or bypass surgery. To me, that's okay. That person was a cardiac death waiting to happen. If it was my sibling or parent, I would be thrilled someone found the problem before I read about their lifeless body being pulled from the water. Am I biased? Of course. I see people with coronary artery disease every day and see what it can do -- death, decreased quality of life, etc. And it appears to be ubiquitous in our society. There are LOTS of 30-something and 40-something people who look like the "picture of health" showing up in my cath lab with heart attacks all the time. The main hope here is that awareness of the problem will get people to look closely at themselves and their lifestyle. Hopefully, some of those will realize that they are at risk and see their physician.

Just my 2 cents.
 
solocavediver said:
So sorry guys, but nearly every advance in science starts out life as an anecdote!

Example: the constancy of the velocity of light was not established instantly; initially there was a certain amount of inconclusive evidence and a lot of discussion. Anecdotes, you might say; a good deal of coffee got consumed in the discussion, I'll be bound. Eventually Michelson and Morley confirmed that it was so, and presently Einstein came up with a brilliant, cogent explanation. And thus the special theory of relativity was born.

Example: the dangers of smoking tobacco were first proposed by King James of England (same one as organized the translation that became the "King James" Bible).
He pronounced the then newly imported weed "noxious to the palate, and dangerous to the lungs". And when he said it, there was no conclusive evidence. It was only an anecdote. He was thus lampooned by people like silentbob and Dr Ebersole as the "biggest fool in Christendom"..... However.....

Example: the dangers of asbestos were, IIRC, noted by a classical Roman author ("a lot of the miners in those mines seem to get sick..."). Of course it was only an anecdote then....
Click to expand...

You are, of course, addressing only those anecdotes that turned out to have substance. How many millions of fruitless lines of enquiry are pursued for every one that results in advancement?
 
solocavediver said:
Right now we have anecdotal evidence of heart disease among rebreather divers.
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Hello,

I don't think this is true. The "rebreathers-cause-heart-attacks-because-of-high-work-of-breathing-and-CO2-retention" notion was promoted by Alex Deas because it gave him a point of attack for criticizing other units with allegedly higher work of breathing than his own Product. He claimed that this theory was supported by his rebreather accident database but on working through the spreadsheet it is clear that many of the cases in which the interpretation was applied had NO supporting evidence (other than involving a unit with higher work of breathing than the one made by Deas). In some cases he diagnosed a "heart attack" when the diver had not even been found and in the absence of an autopsy. It was little more than self-serving agenda-driven sophistry, and unfortunately it deflected attention from the real cause of cardiac events in diving which Doug has addressed in his article. The only objective data on this matter which was published in the AAUS proceedings a few years ago suggested that cardiac events are the disabling injury in a smaller proportion of rebreather deaths than in open circuit scuba deaths. However, this was based on an analysis of only 30 or so events (I don't have the paper in front of me) so it should not be over-interpreted .

Simon M
 
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Thanks Simon and Doug, Always great for those of us without the medical training you guys have to be able to read your thoughts on important subjects. I will say you both do a great job of explaining it in terms that even I (a music major in college) can understand.

See you both at TEKDiveUSA.2014
 
Fair enough Doug, apologies, i mis-interpreted your position as being 'testing'.

I do wonder if people really need to visit for an initial evaluation though. Surely its the old "score your answers to these five questions" type scenario that people could do themselves? (if score is over x, go for a consult).
 
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ebt said:
Fair enough Doug, apologies, i mis-interpreted your position as being 'testing'.

I do wonder if people really need to visit for an initial evaluation though. Surely its the old "score your answers to these five questions" type scenario that people could do themselves? (if score is over x, go for a consult).
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Which is why ScotSAC dropped their consultations and I also understand the Aussies have done the same. It does require divers to be honest with themselves though!

Regards
 
I don't think anyone needs to necessarily go to a physician for a "dive physical" as long as they are truly honest with themselves. Unfortunately, a lot of us still think we are the same person we were in our 20s. Sadly, this is not usually the case.

The main reason to go to a primary care physician regularly is to make sure your "preventive" medicine is being done -- blood pressure check, cholesterol check, colonoscopy, prostate for men, mammograms for women, etc in hopes of avoiding problems or at least catching them at an earlier stage so long term results can be better. It's hard to do some of these things on your own. Not that a few people haven't shown up in an emergency room having done some sort of personal colonoscopy with all kinds of strange items -- coke bottles, umbrellas, ....... :)
 
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