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Cardiovascular System - Valves and Holes

Dr Jules Eden, dive medicine specialist and founder of e-med, answers divers' questions - as published in Sport Diver magazine:
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Q - I am very keen on doing a Divemaster internship but have only dived once in my lifetime! During some travelling a few years ago, I was prevented from diving at the Great Barrier Reef. The reason was that I was born with a hole in my heart (atrial septal defect) but it was corrected when I was 2 years old. I think I still have a murmur (I don't know much about it really) but I don't think it is a problem. I am a fit and healthy 32-year-old now, I can exercise and have never had any problems with it. I go to hospital every two years for a check-up, but if I am considering diving would you recommend that I have a diving medical done by a specialist?

A - Not many people realise that we are all born with a hole in the heart. It lies between the top 2 chambers of the heart, called the atria. When we’re curled up in the womb it’s the presence of this hole that allows oxygenated blood to pass from the placenta through the foetal heart and round the body, bypassing the lungs (which are full of amniotic fluid and therefore not much use). At birth, what’s supposed to happen is that the hole closes; the blood then gets directed around the lungs to pick up its oxygen, before being pumped around the body. This hole is called the foramen ovale (because it’s oval-shaped), and sometimes it doesn’t fully seal over, resulting in a “patent” or permanently open hole – the PFO, of which you may have heard. So a PFO is one type of atrial septal defect (ASD); there are others, of all sorts of shapes and sizes, and I suspect yours must have been rather large if it needed to be operated on at 2 years of age.

To understand why ASD is a problem, a little explaining is required. The right and left sides of the heart are normally separate. The left side of the heart pumps blood around the entire body, and so the pressure is much higher than on the right, which just pumps blood to the lungs. If you have a hole between the two sides, then the right side of the heart becomes exposed to the higher pressure of the left, which in time will overload it. This is called a “left to right shunt”. Fluid will then accumulate in the lungs causing breathlessness, and ultimately the heart will fail. If the ASD is small, this process may take many years, but a large hole can cause heart failure in childhood.

These days the hole is easily closed with an umbrella-like device which is threaded through a groin vein into the heart, and deployed on either side of the ASD (or PFO for that matter). After a few months enough scar tissue has formed to occlude the defect completely, and separate the two sides of the heart again. So at the ripe old age of 32, if you are able to exercise without any symptoms, the heart should be normal, to all intents and purposes. An echo test to put some numbers on the heart function would be useful, but I anticipate it will show a heart that’s perfectly capable of diving.

Q - Hi, I have recently been for a routine medical for my job. My doctor suspected that there may have been a problem so sent me for an ECG, the results for this came back and now he wants me to go for an 'echo' to see if I have an enlarged heart. Have you ever known anyone with an enlarged heart that would be safe to dive? I had a basic dive medical in April 2007 (ie blood pressure, ears, reflexes) and my blood pressure was 120/70 which I understand is OK for a 33 yr old male. My blood pressure was 136/80 on my last test 3 weeks ago.

A - Anyone remember Leonard Rossiter, the lecherous landlord in Rising Damp? Despite being exceedingly fit he died suddenly whilst waiting to go on stage. The cause – undiagnosed thickening of the heart muscle (or HOCM in medical speak). There are different forms of heart enlargement, but the principle can be explained by the old "hot water heating" analogy. Imagine the water as blood, the pump as your heart, the pipes as your arteries and veins, and the water pressure as your blood pressure. If your pipes get furred up, then the pump has to work harder to keep up adequate water pressure, and to cope with this, your heart muscle enlarges. You might think this would make it a more effective pump, but in fact the reverse is true. The heart sits in a stiff sac, so any heart muscle growth occurs inwards, reducing the amount of space within it for blood – so less is pumped with each beat. Exercise capacity therefore drops, and any sudden strain on the heart can push it into failure. This sometimes explains those stories of young people suddenly dropping dead without warning – most recently one lad sprinting to try to set off a speed camera! Heart enlargement produces tell-tale signs on your ECG, which your doc is likely to have spotted, and hence you need a echo test to look closely at the chambers of the heart. It's this test that will determine your fitness to dive.

Q - My brother in law, aged 28,ex-smoker, has a VSD which he has had since birth and this does not seem to affect him physically in any way, he has an excellent exercise tolerance playing for a semi pro football team. No other PMHx, Dx or FHx.

He has been advised by his GP that diving is a big no! Can you please advise as I do feel very sorry for him?

A - Sorry for a semi-pro footballer. Half the money, half the women but a longer FA Cup run than Leeds. Probably.

The fact that he can do all this, shows his heart is physically up to it. But in diving it’s all about which way the blood shunts across the hole, or the D for defect in a Ventricular Septal Defect. VSD.

It’s most likely from the big pumping left ventricle across to the weedier right one, which is OK. But in this cruel world rarely it can go the other way, which can be disaster for a diver. That brings the fizzing nitrogen-microbubbled blood back into the arterial side, missing the lungs where it would be exhaled normally. Bends city. It is rare but it ought to be checked out by a cardiologist first. If all is OK, then kapooow, he can dive.

Q - I am currently completing a UK Sport Diver Medical Form and I answer NO to two questions. For Questions 1: I have a heart murmur - that has been checked by an ECG and is normal. Will that be an issue?
I had recurrent migraines at 14, they stopped after that and then three years ago I had recurrent migraines linked to the pill I was taking - since changing my pill I have had no problems. Will this be a problem for Question 10?

A - You should be fine. Most murmurs are what they call a flow murmur. Just the sound of the blood rushing through the heart. An ECG won't necessarily show a murmur but it would show signs of heart changes if it were a pathological one.

Migraines are only a problem if you get one underwater. Searing headaches and visual distortion aren't a good combination with diving. But as you have resolved the problem by switching the pill to another one, you will be fine as well.

Q - I am approaching you as I had a "Hole in the heart" which was patched at about 8 Months old. ( I think it's known as a VSD?) And I wish to know what steps I need to take (if any!) before embarking on deeper diving. I was under Great Ormond Street hospital until the age of 14, when I was informed that no more check ups are necessary, and I was cleared for a normal/active life.


I am now 28 and have asked for a referral letter from my GP to be sent to a cardiologist that I know who consults from Guy's Hospital. He has agreed to see me and give me an echocardiogram once he has received the referral letter. Is this necessary after such a long period of time?

A - A VSD is better known as a "ventriculo-septal defect". This is where a hole between the 2 ventricles still exists after birth and is picked up on listening to the heart sounds when you are a baby.

A quick echocardiogram, a small op and its fixed. Well in your case anyway. The potential problem with holes in the heart is that if they shunt blood from the right to the left side problems can ensue. Nitrogen bubbles from the venous circulation can get into the left side an off into the arterial circulation, so missing being exhaled and causing all manner of bend symptoms. But your luck is in here. Those with a VSD tend to shunt blood the other way, from left to right so the former doesn't happen. So the understanding is that divers with a small untreated VSD should be fine to dive. However blood shunted from left to right with each beat of the heart can, in periods of exercise, potentially put too much blood back into the heart/lung circulation and block it up causing pressure on both those organs. I would advise a diver with an untreated VSD to see a doc for an exercise test to make sure this doesn't happen. But back to your case. It was treated at birth, you have been given the all clear too, but with the offer of a free echocardiogram how can you turn that down!

I would have it just to make really sure that all is well. If there is still a tiny fault then you should be OK, bigger hole and get the exercise test one. But I reckon your chances are near enough 100% that you shouldn't lose any sleep over it.

Q - I have just had a something called Aortic Valve Incompetence diagnosed after a long fever. My doctor doesn't know if I should continue to dive.

I have been diving for many years now without any problems.

What should I do?

A - This problem is not what we call an " absolute contraindication " to diving like Aortic Stenosis where the valve stays tightly shut limiting the flow of blood out of the heart to the body.

It is a "relative contraindication", which means it depends on how loose and floppy the valve is, as to whether you should continue diving.

At it's worst, this condition means that blood exiting the heart falls back into the chamber slowing down the new blood filling the chamber up for the next beat.

This can cause a back pressure on new oxygenated blood arriving to the heart from the lungs. What happens then is that your lungs get waterlogged making you short of breath. You can se why this would be incompatible with diving if it were that bad in yourself. However , if the problem is only minor, and the valve stops most of the blood from coming back into the heart then you may well be fit to dive.

The best thing to do is discuss it with a cardiologist, make sure you have regular ultrasounds of the heart, called echocardiograms, and if you get any symptoms of shortness of breath, see your doctor quickly.

Q - I have not been allowed onto any PADI compatible course abroad due to my medical condition. I am hoping that I can get this medical hurdle and then the training cleared in the UK so that this will not be a problem when I visit Sharm in October.
My condition is as follows: -

I was born with a congenital heart condition. This included aortic stenosis,and various other problems. The condition was operated on in 1977 - the stenosis was removed. Although this operation was successful, I have a leaky valve (the left ventricle) and so I have a systolic murmur. The hospital tells me that the heart is 20% overworking.

The consultant that I saw thought that my stenosis would reoccur by the time I was 18, but it has not as yet reoccurred. I have annual check ups at the Royal Brompton National Heart and Lung hospital, which includes a full range of appropriate tests.

The hospital has not objected to any activity that I have discussed with them in the past - I do not undertake super-strenuous exercise such as marathons etc, but I have been to a gym in the past, and I regularly play football. I did ask them about diving, but they said that they did not feel qualified to make a judgement - my GP says the same.

I have swum regularly since I was very young, and am reasonable. I have no problems holding my breath, or swimming underwater.

Please let me know if there is already a good reason why I will fail a diving medical, if not, how and when I can get a medical, and if this is the case, if there are any actions that I need to take such as requesting any details from the Brompton.

A - Bad news I am afraid. Although your stenosis i.e. closure of the main valve that regulates the oxygenated blood going out of the heart is fixed, the other valve will cause you problems. This is the mitral valve and sits between the left atrium and venticle. When the ventricle contracts, whooshing blood out of the heart, this valve tops the blow back of blood into the atrium and lungs. If it is faulty and leaks, you get a back pressure into the lungs. Blood will pool there and affect your ability to oxygenate blood. [hope you are still with me here!]

This is pulmonary oedema and can be fatal for the diver. Frothy sputum on ascent, blood in the spit, the works.

Add the fact that your heart is already overworking anyway and sadly you wont get into a dive docs door, let alone pass the medical.

(other dive medical questions)



   


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