Patent Foramen Ovale: Background and Impact on Divers

Common anatomical defects of the heart were identified as risk factors for decompression sickness in the 1980s. Between 17% and 35% of the normal population are found to have an anatomical atrial septal defect, or patent foramen ovale (PFO), beyond infancy (1). The incidence among divers who have suffered from serious neurological decompression sickness symptoms was reported to be as high as 61% (2) or 66% (3). This article will present an overview of the condition with emphasis on the implications for the diving population.