A patent foramen ovale (PFO) is a hole in the heart that didn't close the way it should after birth. Most people with a patent foramen ovale don't need treatment.The team at Arizona Heart Arrhythmia Associates can diagnose your structural heart defect and provide treatments to keep your heart working as it should. Learn more about the causes and complications of this condition in which a hole in the heart doesn't close the way it should after birth. A patent foramen ovale occurs when a hole that is always present in a newborn's heart fails to close as it should once the lungs begin to function after birth. A patent foramen ovale (PFO) is a hole in the heart that should have closed after birth. The foramen ovale is a hole in the wall between the left and right atria of every human fetus. This hole allows blood to bypass the fetal lungs. Patent foramen ovale (PFO) is a hole between the left and right atria (upper chambers) of the heart. This hole exists in everyone before birth.