Overview

What Is Patent Foramen Ovale?

A patent foramen ovale (PFO) is a hole in the heart. It is a congenital condition. This means you are born with it. PFO may increase the risk of stroke or transient ischemic attack (TIA) in adults. PFO is not a neurological disorder. Rather, it is a congenital heart defect that may cause a stroke.

Before birth, each fetus has a small opening between the upper left and right chambers (atria) of the heart. This opening is called a foramen ovale. A foramen ovale allows blood to go around or bypass the lungs of the fetus. They do not use their lungs during development. Rather, oxygen from the mother is sent across the placenta to the fetus. In most cases, the foramen ovale closes on its own soon after birth. If the foramen ovale stays open (patent), blood may leak between the two atria and a PFO is formed.

Blood flow across the PFO may cause a blood clot to form. The blood clot may break free, travel through the heart and into the brain. This causes a stroke.

If a person has a stroke or TIA without warning or risk factors, it may be caused by a PFO. About one in five Americans has a PFO. It often does not cause symptoms.