A patent foramen ovale (PFO) is a hole in the heart that didn't close the way it should after birth.
During fetal development, a small flap-like opening — the foramen ovale (foh-RAY-mun oh-VAY-lee) — is usually present between the right and left upper chambers of the heart. It normally closes during infancy. When the foramen ovale doesn't close, it's called a patent foramen ovale.
Although it's common to have a patent formen ovale, most people with the condition never know they have it. A patent foramen ovale is often discovered during tests for other problems. Learning that you have a patent foramen ovale is understandably worrisome, but most people never need treatment for this disorder.