A patent foramen ovale is a small, flaplike opening in the wall between the upper chambers of the heart. 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 and atrial septal defect closure is a routine procedure to close holes in the upper chambers of the heart. PFO often has no symptoms. Many people don't need treatment unless they're at risk of stroke or blood clots. Interestingly, the presence of a PFO is strongly associated with migraine with aura, migraine aura without headache, and chronic migraine. Most people don't have symptoms. The foramen ovale is a cardiac shunt present in the embryologic phase to bypass the lungs. After a brief overview of the anatomy of a PFO, this article considers the evidence for PFO closure in cryptogenic stroke.