A condition from infancy, patent foramen ovale often goes undiagnosed through adulthood.

When a baby/fetus is developing in the uterus, a small, flap-like opening forms in the wall (septum) between the right and left upper chambers of the heart (right atrium and left atrium). This opening occurs naturally before birth and usually closes within days of being born. In about one out of five people, however, this opening persists throughout life and is called patent foramen ovale (PA-tunt fo-RA-mun o-VA-le), or PFO. The opening that occurs in patent foramen ovale may allow blood to flow from the heart’s right atrium to the left atrium and vice versa.

Most people with patent foramen ovale don’t know they have the condition. That’s because patent foramen ovale usually doesn’t cause any signs or symptoms. Most people with patent foramen ovale don’t need treatment, although closing the opening with a device is an option and may be helpful in patients with prior stroke or difficult to control headaches.