A PFO closure uses a medical device to close an opening between your heart's two upper chambers. You only need this opening as a fetus.Many people don't need treatment unless they're at risk of stroke or blood clots. Premier Health offers a full range of heart and vascular care – preventive, diagnostic, nonsurgical, surgical, and rehab – across Southwest Ohio. A patent foramen ovale is a small, flaplike opening in the wall between the upper chambers of the heart. 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. 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. The foramen ovale (feh-RAY-men oh-VAL-ee) is a normal opening between the upper two chambers (the right atrium and left atrium) of an unborn baby's heart. However, it may cause serious complications under certain circumstances.