During fetal development, a small flap-like opening (the foramen ovale) is normally present in the wall between the upper left and right chambers of the heart (atria). The opening normally closes during infancy. A patent foramen ovale (PFO) refers to the opening of the flap when the foramen ovale does not close the way it should be, after birth. This may result in blood clot passing from right atrium to left atrium, resulting in stroke if the clots go to the brain. PFO can be closed by inserting a device through the blood vessels in the groin (percutaneous transcatheter approach).Most people with the condition never know they have it. A PFO is often discovered during tests for other problems.