Post by LSDeep on Nov 23, 2005 14:33:33 GMT -5
By Louise Murray
Of the 80,000 divers who read this article, about 25,000 have a minor heart defect called a PFO that makes them up to 13 times more likely to end up in a recompression chamber. But what is a PFO and what can you do about it if you have one? Louise Murray finds out
What is a PFO?
A Patent Foramen Ovale or PFO is a hole between the two upper chambers of the heart and is something that we are all born with. In most of us this heals up after birth, but in one in three people the hole persists. This hole causes problems for divers, as it allows blood potentially loaded with nitrogen bubbles to jump or shunt across from the left-hand side of your heart to the right-hand side where your arteries supply the brain and other parts of the body. A stray nitrogen bubble in your brain or spinal cord could lead to a serious decompression illness (DCI). The blood in the left-hand side of your heart should flow to your lungs, where such bubbles would be removed.
How does it affect divers?
New research led by Dr Sandra Torti from the University of Bern in Switzerland looked at 230 divers in detail, each with more than 200 logged dives, and all of whom had always dived strictly according to tables. None knew in advance whether they had a PFO, but all were tested.
Examining the diving history of each participant, the scientists found that those with PFOs more than 9mm in diameter had a much higher risk of DCI. They were up to 13 times more likely to have ended up in a chamber for treatment and five times more likely to have had major DCI than divers without a PFO or divers with a small PFO.
Research by Dr Peter Wilmshurst, a British expert in this field, had already confirmed the importance of PFO size. He says: ‘There is no doubt that here, as in most things, size really does matter. The bigger your PFO, the greater your chance of getting bent. But to put this into perspective, only 1.3 per cent of the population have PFOs that are 10mm in diameter or larger and these people suffer between 30 and 40 per cent of all bends.’
However, many divers with a PFO have never had DCI, so the prevailing view is that there is no justification for routine screening. Seventy five per cent of divers with unexplained DCI turn out to have PFOs. These are divers who have obeyed all the rules and ascended slowly.
‘Just why some people are affected on an innocuous dive to 11m, when they have already completed thousands of dives without incident, is not understood,’ says Dr John King, a Harley Street diving doctor. ‘I know of a diver with more than 15,000 dives who has a large PFO but has never complained of any symptoms at all. We still have a lot to learn about what is going on.’ Other diving doctors think that there may be a relationship with dehydration prior to the dive compounded by dehydration during the dive.
‘What we do find,’ says King, ‘is that some divers who end up diagnosed with PFO have been having post-dive symptoms of DCI after many, if not most of their dives, but have been in denial or dismissed the symptoms as unimportant. To do this is to dice with disability.’
What can you do about it?
Once a consultation establishes that a PFO might be responsible, the doctor will refer the diver to a cardiologist. Finding a suitably qualified cardiologist can be tricky, as there are few in the UK who are able to reliably diagnose a PFO and offer sensible advice to divers. Once a diver has seen one of these specialists, an echocardiogram is performed on the patient’s heart.
An echocardiogram is similar to the familiar ultrasound used on pregnant women to show the baby inside. A harmless bubble solution is injected into a vein and the echocardiogram will show if bubbles are passing from the right to the left of the heart. If they are, there is a PFO.
The next step involves a discussion with the cardiologist of the pros and cons of going ahead with a PFO closure. John King says: ‘Once a patient of mine comes back from the cardiologist with a PFO suitable for closure, I always recommend it. Most divers will simply not continue diving under the restrictions placed upon them.’
Advice for those continuing to dive with a PFO is conflicting and depends on the size of the PFO. Some advocate a 15m depth limit on nitrox only and others say that 10m should be a maximum and preferably on closed-circuit rebreathers, and if not, nitrox. Many diving doctors advocate no diving at all until the PFO is repaired.
The operation to close a PFO is relatively straightforward, although it does require considerable skill to place a sealing device to close the hole. The device is inserted using keyhole surgery into the femoral vein in the leg, and its positioning over the hole is checked. The patient is usually under anaesthetic for about an hour.
The cells of the heart grow over the device and the repair is confirmed by another echocardiogram three months later. Once checked, people may return to diving safely.
Conservative diver
Becky Varns
Becky, 22, is a PADI instructor and had about 800 dives under her belt when diagnosed with a PFO last year. She describes her diving as fairly conservative. After every dive Becky came up with a headache, anything from something minor to a full-blown migraine, and often pulled muscles. She associated the headaches with skip breathing and dehydration, though she took care to drink water and eat properly.
One weekend in the winter of 2002, she was teaching at Stoney Cove. After two days of diving well within tables, and some hours after her last dive, she turned awkwardly and experienced sharp pain in her lower back. The next day a rash appeared during a hot shower. DAN UK referred her to Whipps Cross chamber in East London and after the usual tests, the hyperbaric doctor there told Becky that she had been getting bent on every single dive that she had ever done. The headaches were neurological bends and the pulled muscles and muscular pain were other manifestations of DCI. She was advised never to dive again.
Tests completed, Becky decided to visit a hyperbaric doctor to discuss her future as stopping diving was not an option. Dr King suggested that she might have a PFO, which a further test confirmed. Fifteen months later she had the operation to seal her large PFO. ‘It’s really surprising: even immediately post-op, I felt like the bionic woman, a completely different person.’
Skin bend alert
Valerie JenkinS
Valerie, 47, has been diving since 1989, is a BSAC dive leader and has done a total of 350 conservative, no-stop dives.
In October 2003, after a couple of short 25 and 30m dives in the Florida Keys, Valerie felt nauseated more than an hour after coming out from the dive. Skipping the afternoon dive she went to lie down, feeling fluey and hot. ‘By five I felt okay, never thought any more of it, but while dressing the next day, my stomach felt sore and bruised, which I put down to carrying extra weight. I did another 30m dive on nitrox, and after the dive a big white mark appeared on my abdomen, like a blister without fluid, and tender. I continued to dive and the mark got bigger. When I stopped diving it gradually disappeared.’ Valerie had had a rare lymphatic bend followed by a skin bend.
When she returned home, she went to see her local GP and was referred to Dr Peter Wilmshurst in December 2003. In April 2004 she was diagnosed with a small, 6.3mm PFO and went on the waiting list for an operation. A lucky cancellation followed and she had her operation privately in July 2004 with Dr Morrison in Merseyside.
Valerie was given the all clear in September that year when her echocardiogram was repeated. She says: ‘I felt a bit worried at first. Logically you know that it’s not going to move but I didn’t want to do too much too early. I would say that I felt fine after a month.’
Allergy denial
Edwin Bennet
Edwin, 37, manages a dive shop in Bexleyheath, and has clocked up around 950 dives in the UK and abroad. He admits he pushes the limits with his diving but says he doesn’t think stupidly so. Edwin has done some long, deep dives, but four years ago he started having problems at 25m.
‘My heart felt as though it was pounding out of my chest and I was losing consciousness during each dive. It was as though I had had too much to drink. It started at about 30m but was worst when I was coming back up to 25m, and happened on every single dive.’
Edwin thought it was just in his head and didn’t put the symptoms down to anything serious. Even the skin lesions he started to get he put down to his food allergy.
‘I didn’t go diving for four or five months but eventually my colleagues booked me in for an appointment with Dr King,’ he explains. In August this year, King examined Edwin and did an echocardiogram before confirming that there was something wrong with his heart. In a couple of days he saw a cardiologist and had the bubble solution injection and ultrasound.
When Edwin was told he had a medium-sized PFO he wasn’t too worried. ‘I’d known quite a few people with the same problem, so I wasn’t scared about it,’ he says. ‘It was quite a relief to know it wasn’t in my head!’
Edwin is due to have his operation soon and, having spoken to other people who have had the procedure, he’s confident he’ll soon be back diving.
CHECK OUT
Go to see a diving doctor or hyperbaric specialist to have a potential PFO checked out if:
You have experienced any symptoms that might have been DCI either during or shortly after a dive|
You have a history of ‘undeserved bends’, that is to say where you dived to or close to tables but still got bent
You have a family history of early stroke or migraine that is associated with aura – visual or auditory hallucinations.
If you are diagnosed with a PFO, the operation will cost about £11,000 if conducted privately and there will be a wait of between three and 12 months, depending on what part of the country you live in. On the NHS, waiting lists are currently between six months and more than a year.
Of the 80,000 divers who read this article, about 25,000 have a minor heart defect called a PFO that makes them up to 13 times more likely to end up in a recompression chamber. But what is a PFO and what can you do about it if you have one? Louise Murray finds out
What is a PFO?
A Patent Foramen Ovale or PFO is a hole between the two upper chambers of the heart and is something that we are all born with. In most of us this heals up after birth, but in one in three people the hole persists. This hole causes problems for divers, as it allows blood potentially loaded with nitrogen bubbles to jump or shunt across from the left-hand side of your heart to the right-hand side where your arteries supply the brain and other parts of the body. A stray nitrogen bubble in your brain or spinal cord could lead to a serious decompression illness (DCI). The blood in the left-hand side of your heart should flow to your lungs, where such bubbles would be removed.
How does it affect divers?
New research led by Dr Sandra Torti from the University of Bern in Switzerland looked at 230 divers in detail, each with more than 200 logged dives, and all of whom had always dived strictly according to tables. None knew in advance whether they had a PFO, but all were tested.
Examining the diving history of each participant, the scientists found that those with PFOs more than 9mm in diameter had a much higher risk of DCI. They were up to 13 times more likely to have ended up in a chamber for treatment and five times more likely to have had major DCI than divers without a PFO or divers with a small PFO.
Research by Dr Peter Wilmshurst, a British expert in this field, had already confirmed the importance of PFO size. He says: ‘There is no doubt that here, as in most things, size really does matter. The bigger your PFO, the greater your chance of getting bent. But to put this into perspective, only 1.3 per cent of the population have PFOs that are 10mm in diameter or larger and these people suffer between 30 and 40 per cent of all bends.’
However, many divers with a PFO have never had DCI, so the prevailing view is that there is no justification for routine screening. Seventy five per cent of divers with unexplained DCI turn out to have PFOs. These are divers who have obeyed all the rules and ascended slowly.
‘Just why some people are affected on an innocuous dive to 11m, when they have already completed thousands of dives without incident, is not understood,’ says Dr John King, a Harley Street diving doctor. ‘I know of a diver with more than 15,000 dives who has a large PFO but has never complained of any symptoms at all. We still have a lot to learn about what is going on.’ Other diving doctors think that there may be a relationship with dehydration prior to the dive compounded by dehydration during the dive.
‘What we do find,’ says King, ‘is that some divers who end up diagnosed with PFO have been having post-dive symptoms of DCI after many, if not most of their dives, but have been in denial or dismissed the symptoms as unimportant. To do this is to dice with disability.’
What can you do about it?
Once a consultation establishes that a PFO might be responsible, the doctor will refer the diver to a cardiologist. Finding a suitably qualified cardiologist can be tricky, as there are few in the UK who are able to reliably diagnose a PFO and offer sensible advice to divers. Once a diver has seen one of these specialists, an echocardiogram is performed on the patient’s heart.
An echocardiogram is similar to the familiar ultrasound used on pregnant women to show the baby inside. A harmless bubble solution is injected into a vein and the echocardiogram will show if bubbles are passing from the right to the left of the heart. If they are, there is a PFO.
The next step involves a discussion with the cardiologist of the pros and cons of going ahead with a PFO closure. John King says: ‘Once a patient of mine comes back from the cardiologist with a PFO suitable for closure, I always recommend it. Most divers will simply not continue diving under the restrictions placed upon them.’
Advice for those continuing to dive with a PFO is conflicting and depends on the size of the PFO. Some advocate a 15m depth limit on nitrox only and others say that 10m should be a maximum and preferably on closed-circuit rebreathers, and if not, nitrox. Many diving doctors advocate no diving at all until the PFO is repaired.
The operation to close a PFO is relatively straightforward, although it does require considerable skill to place a sealing device to close the hole. The device is inserted using keyhole surgery into the femoral vein in the leg, and its positioning over the hole is checked. The patient is usually under anaesthetic for about an hour.
The cells of the heart grow over the device and the repair is confirmed by another echocardiogram three months later. Once checked, people may return to diving safely.
Conservative diver
Becky Varns
Becky, 22, is a PADI instructor and had about 800 dives under her belt when diagnosed with a PFO last year. She describes her diving as fairly conservative. After every dive Becky came up with a headache, anything from something minor to a full-blown migraine, and often pulled muscles. She associated the headaches with skip breathing and dehydration, though she took care to drink water and eat properly.
One weekend in the winter of 2002, she was teaching at Stoney Cove. After two days of diving well within tables, and some hours after her last dive, she turned awkwardly and experienced sharp pain in her lower back. The next day a rash appeared during a hot shower. DAN UK referred her to Whipps Cross chamber in East London and after the usual tests, the hyperbaric doctor there told Becky that she had been getting bent on every single dive that she had ever done. The headaches were neurological bends and the pulled muscles and muscular pain were other manifestations of DCI. She was advised never to dive again.
Tests completed, Becky decided to visit a hyperbaric doctor to discuss her future as stopping diving was not an option. Dr King suggested that she might have a PFO, which a further test confirmed. Fifteen months later she had the operation to seal her large PFO. ‘It’s really surprising: even immediately post-op, I felt like the bionic woman, a completely different person.’
Skin bend alert
Valerie JenkinS
Valerie, 47, has been diving since 1989, is a BSAC dive leader and has done a total of 350 conservative, no-stop dives.
In October 2003, after a couple of short 25 and 30m dives in the Florida Keys, Valerie felt nauseated more than an hour after coming out from the dive. Skipping the afternoon dive she went to lie down, feeling fluey and hot. ‘By five I felt okay, never thought any more of it, but while dressing the next day, my stomach felt sore and bruised, which I put down to carrying extra weight. I did another 30m dive on nitrox, and after the dive a big white mark appeared on my abdomen, like a blister without fluid, and tender. I continued to dive and the mark got bigger. When I stopped diving it gradually disappeared.’ Valerie had had a rare lymphatic bend followed by a skin bend.
When she returned home, she went to see her local GP and was referred to Dr Peter Wilmshurst in December 2003. In April 2004 she was diagnosed with a small, 6.3mm PFO and went on the waiting list for an operation. A lucky cancellation followed and she had her operation privately in July 2004 with Dr Morrison in Merseyside.
Valerie was given the all clear in September that year when her echocardiogram was repeated. She says: ‘I felt a bit worried at first. Logically you know that it’s not going to move but I didn’t want to do too much too early. I would say that I felt fine after a month.’
Allergy denial
Edwin Bennet
Edwin, 37, manages a dive shop in Bexleyheath, and has clocked up around 950 dives in the UK and abroad. He admits he pushes the limits with his diving but says he doesn’t think stupidly so. Edwin has done some long, deep dives, but four years ago he started having problems at 25m.
‘My heart felt as though it was pounding out of my chest and I was losing consciousness during each dive. It was as though I had had too much to drink. It started at about 30m but was worst when I was coming back up to 25m, and happened on every single dive.’
Edwin thought it was just in his head and didn’t put the symptoms down to anything serious. Even the skin lesions he started to get he put down to his food allergy.
‘I didn’t go diving for four or five months but eventually my colleagues booked me in for an appointment with Dr King,’ he explains. In August this year, King examined Edwin and did an echocardiogram before confirming that there was something wrong with his heart. In a couple of days he saw a cardiologist and had the bubble solution injection and ultrasound.
When Edwin was told he had a medium-sized PFO he wasn’t too worried. ‘I’d known quite a few people with the same problem, so I wasn’t scared about it,’ he says. ‘It was quite a relief to know it wasn’t in my head!’
Edwin is due to have his operation soon and, having spoken to other people who have had the procedure, he’s confident he’ll soon be back diving.
CHECK OUT
Go to see a diving doctor or hyperbaric specialist to have a potential PFO checked out if:
You have experienced any symptoms that might have been DCI either during or shortly after a dive|
You have a history of ‘undeserved bends’, that is to say where you dived to or close to tables but still got bent
You have a family history of early stroke or migraine that is associated with aura – visual or auditory hallucinations.
If you are diagnosed with a PFO, the operation will cost about £11,000 if conducted privately and there will be a wait of between three and 12 months, depending on what part of the country you live in. On the NHS, waiting lists are currently between six months and more than a year.