Patent foramen ovale and decompression sickness


 * Associate Editors-In-Chief: Priyamvada Singh, M.B.B.S. [mailto:psingh@perfuse.org]

Overview
Decompression illness is associated with a 5 to 13 fold increased incidence of a patent foramen ovale. The risk increases with an increase in defect size. Device closure can be considered in divers with unexplained decompression illness, especially those who wish to continue diving. The number of ischemic brain lesions were twice as common among patients with a patent foramen ovale than in those without it.

Pathophysiology
Decompression illness can occur in divers as they ascend from deeper waters to the surface. The change in pressure (from high to low) causes gas bubbles to form in the bloodstream. The gas bubbles come from inert gases like nitrogen. These gases are present in the different parts of the body like joints, spine and skin pores. If nitrogen is forced to come out of solution too quickly, bubbles form in parts of the body causing the signs and symptoms of the "bends". Signs and symptoms of the bends include itching skin and the development of rashes, joint pain, sensory system failure, paralysis, and death. These gas bubbles can enter the venous system and can enter the systemic circulation via inter-atrial communications such as a patent foramen ovale or an atrial septal defect. This paradoxical embolism or right-to left shunt can in turn be associated with complications such as ischemic brain injury (TIA or stroke).