Divers with a patent foramen ovale (PFO) or hole in the heart are five times more likely to suffer a major episode of decompression illness, according to a team of researchers from University Hospital Bern, Switzerland.
The link between the presence of a PFO and an increased risk of decompression illness has long been acknowledged. With roughly 25-30% of the population having a PFO, most divers with the condition will not be aware that they have a hole in the heart.
230 divers with over 200 dives each were asked to examine their dive logs, analyse their diving history and describe any decompression related illness in the context of the dive undertaken. Ultrasound examinations of the divers’ hearts then revealed whether a PFO was present.
27 percent of the divers in the study were found to have a PFO, and 27% – over a quarter – of this group had suffered at least one serious neurological bend* requiring hyperbaric treatment. Only 6% of the divers without a PFO had suffered the type of major DCI identified in the research.
However, researchers found that divers with a small hole in the heart, classified as a grade 1 PFO, do not appear to face an increased risk. The research demonstrated that the larger the size of the PFO, the greater the chance of the diver suffering a decompression incident.
The research was reported in the European Heart Journal (June 2004)
* The type of bend benchmarked in the research as a serious DCI was defined by the following symptoms: loss of consciousness, and impaired bowel or bladder control after the dive.
Previous (1999) research by Dr Michael Knauth of Heidelberg University showed that divers with PFOs were much more likely to show evidence of small lesions, scars and areas of dead tissue in their brain tissue.
