>Ann was a healthy, slim, physically active 41-year-old woman who worked as a divemaster on weekends, regularly going to 70-90 feet for 45 minutes and unloading up to 40 tanks after the dive. In 11 years of diving, she completed more than 1,200 dives and experienced a number of episodes of what she considered to be decompression sickness (DCS). She always wondered why she was the only one in the group who got hit.
>"I have suffered from skin DCS, had serious pulmonary issues and visual disturbances after diving, but I never went to the chamber because everything was pretty much resolved over several hours," Ann said. "The most recent episode started with the typical burning in my left upper chest, accompanied by the weird vision and lung burning.
>"Over the next 30 minutes, I had a lump grow there about the size of a lemon, and it turned to a nasty shade of purple like a bruise. The lung pain and weird vision subsided over the next several hours. The lump decreased the next day, and the bruising was gone in about 10 days."
>When she read about PFO, she visited a cardiologist, who examined her using transthoracic echocardiography (TTE). The test revealed that the wall between her left and right forechambers was floppy and had a hole about 5mm in diameter. The cardiologist suggested that she either repair the hole in her heart or not dive again. Thoughts of intervention made her nervous, but she wanted to continue diving and agreed to have a transcatheter closure.
>One week after the closure she returned to her running routine, but she was getting confused at work. One time she felt difficulty breathing, could not move her limbs and passed out. She was diagnosed with anxiety attacks, high blood pressure and low potassium. It is possible that these same symptoms could have been construed as DCS had they occurred after diving. It is also possible that these procedures were side effects of the PFO closure procedure.
>Recently Ann returned to diving, but she limits herself to short, shallow excursions. She reports experiencing an arrhythmia acquired after the closure that feels like corn popping in her chest, but she has chosen not to worry about it.
>Tom is an active 36-year-old diver. He does a lot of wreck and cave diving that also involves decompression profiles. From 2003 through 2007 he recorded 460 dives.
>"Sometimes I experience subclinical DCS symptoms: general fatigue and abdominal cramps that manifest early post-dive and usually clear up within hours," Tom said.
>Five years ago he experienced a serious bout of DCS. About 20-30 minutes after surfacing from his second 130-foot wreck dive of the day, he complained of shortness of breath and lost strength in the entire left half of his body. In the emergency room he received oxygen, and his symptoms resolved. He was not referred for additional treatment.
>Two years later he experienced a similar incident. It occurred after two air dives on a wreck in 176 feet of water despite decompression on 70 percent nitrox and a four-plus-hour surface interval between dives. Chokes started within 10 minutes followed shortly by left-side paralysis and unconsciousness.
>He stayed in his hotel bed all night breathing oxygen. The next morning he still had some numbness and tingling. He was airlifted to another island, where he was treated in a hyperbaric chamber 24 hours after finishing his last dive. All remaining symptoms resolved after one U.S. Navy Treatment Table 6, and he returned to diving two weeks later.
>After reading about PFO, Tom insisted on being tested. His first test came back normal, but another episode of symptoms led to a second test, which revealed the PFO. He was already scheduled for closure when he got his third major DCS hit. It occurred after a cave dive to 95 feet for a total time of 186 minutes. About one hour after surfacing, he collapsed. He was confused and again felt weakness of his left side. Symptoms improved within 20 minutes on oxygen and resolved completely with recompression treatment.
>Following his PFO closure in 2008, he has logged more than 400 dives, nearly all on closed-circuit rebreathers with high-oxygen breathing gases. He has not had any subsequent major DCS hits, but he does occasionally suffer from fatigue, skin tenderness and abdominal cramping — symptoms similar to those that existed for him prior to his closure.
>Ely started diving when she was 15. In a few years she progressed to deep wreck and cave diving. As a young diver, she experienced an episode of numbness in her arms and another of weakness in her legs; these symptoms lasted for several hours. At 22, after another deep dive, she could not see or walk and was treated in a hyperbaric chamber. Some tingling and numbness in her leg remind her still of that incident. But nothing could have deterred her from diving. She even made diving her business.
>"I learned early in my career that I had to ascend slower and stay longer on decompression stops than other divers in the group," Ely said.
>Despite these precautions, she suffered several vertigo hits and "a lot of skin bends" with breast pain and swelling. Using nitrox for diving and oxygen for decompression helped, but hits still occurred occasionally. Sometimes she became bent after a minor deviation from her usual schedule and sometimes without an obvious reason.
>When she could not stand up after a dive to 170 feet, she was treated for the second time in a recompression chamber. Five years ago she had a severe vertigo that lasted for 30 hours. She self-administered surface oxygen and did not go to a hospital.
>Last year she was diagnosed with PFO. A doctor told her it was a pretty large hole and referred her for closure.
>Compared to her previous 21 surgical operations, including knee replacement, hip replacement and ankle reconstruction, the closure itself was quick and painless. She was awake and watching it on the monitor. Once the tip of the catheter appeared in her heart, she saw something like a small umbrella popping, then immediately another one, and the closure was in place, all in less than 10 minutes. She had to lie still for another four hours. It took 40 minutes of mechanical pressure on her groin artery to stop bleeding.
>She had to take Coumadin, a blood thinner; she did not like it because of her previous bad experience with it. After six weeks, her doctor replaced Coumadin with aspirin. In addition, she takes Voltaren for arthritis.
>Against medical advice, she resumed diving just six weeks after the closure. After a couple of months of recreational diving, she went back to extensive cave diving, and, by the time she was interviewed, she had made about 20 long, decompression dives on closed-circuit rebreathers. For the first time, her buddy got bent instead of her, but he made an obvious mistake. She believes that she dives conservatively.
>Our three divers are all very enthusiastic about PFO closure, but their stories reveal some of the difficulties in making a clear assessment of the risk/benefits of the procedure. Let us consider some of the possible issues.
>Analysis: PFO, the Risk of DCS and the Benefits of Closure
>Have our divers been hit by DCS more often than expected?
>The answer may seem obvious, but not all divers who experience multiple bouts of DCS symptoms have a PFO. Divers who do deep dives and decompression dives are at greater risk of DCS, and our three divers were all in that category. In addition, their accounts of DCS included symptoms like fatigue, skin swelling and mottling, breast pain and migraine aura without headache. These symptoms often go unreported and may be more prevalent in the total population of divers than we know. Even our divers reported their skin bends only after they suffered severe neurological DCS. If mild symptoms are discounted, the remaining serious DCS in our divers may not be extraordinary.
>Were their DCS hits "undeserved?"
>The risk of DCS is a continuum that increases with depth and duration of dives; thus it is impossible to draw the line separating "deserved" from "undeserved" DCS. Based on their stories, it appears that our divers experienced their most severe hits after making riskier dives. Unfortunately, we do not have sufficient records to compare these dives with symptom-free dives.
>What was the PFO like in these divers?
>Two of the divers had a large right-to-left shunt due to the atrial septal defect. One diver had also an atrial septal aneurism, which is an additional risk factor for stroke and an indication for closure regardless of diving.
>What was their experience with the medical procedures of closure?
>Overall, the procedure of closure did not seem to stress our divers much, but their enthusiastic expectations may have helped them discount the burden. Perhaps the most burdensome aspect of the procedure for these divers was the prohibition against diving in the requisite post-operative period.
>They did not mind taking blood thinners for several months, although some experienced more bruising during that period. One diver developed mild heart arrhythmia but did not think much of it. It seems that none of them has experienced any severe complications post-closure, but there are some risks that will stick with them for their entire lives.
>Did PFO closure prevent DCS symptoms in our divers?
>One of our divers has been diving for a year or more post-closure, and two other divers continue making their gradual comeback. So far they have experienced only a few minor symptoms, and they think that closure provided them with the margin of safety they expected. The objective assessment must take into account possible effects of conscious or spontaneous adjustments such as using closed-circuit gear with higher concentrations of oxygen in their breathing gas and avoiding vigorous exercise during dives, all of which reduce the risk of DCS.
>Closure of PFO decreases the chance of bubbles passing to the arterial side, but DCS may occur without arterial bubbles. It is wise to adhere to conservative dive practices regardless of PFO or its closure.
>PFO closure as a prevention of DCS is a controversial measure. Data for an objective risk/benefit analysis is not currently available. To answer whether divers with PFO closure are better off than divers who continue diving with PFO, DAN® and interventional cardiologist Dr. Douglas Ebersole have recently started a prospective study. For more information, visit www.DiversAlertNetwork.org
>© Alert Diver — Spring 2010