A patent foramen ovale or PFO is a defect in the wall between the two upper chambers of the heart. PFO closure is a minimally invasive procedure that involves a small incision in the groin area.Most people with Patent Foramen Ovale do not need treatment. The medical term for this finding is called a patent foramen ovale, or PFO for short. 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. This review discusses results of these studies, evaluation strategies for PFO and PFO closure, and additional indications for PFO closure. 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 is a small, flaplike opening in the wall between the upper chambers of the heart. If you have a PFO and low blood oxygen levels or an unexplained stroke, you may need a procedure to close the hole.