In this heart surgery, the surgeon uses stitches to close the PFO . 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. A patent foramen ovale occurs when the hole doesn't seal as it should. Most PFOs don't need to be closed. A PFO closure fills an opening between your heart's two upper chambers. The foramen ovale usually closes 6 months to a year after the baby's birth. Percutaneous closure of a patent foramen ovale (PFO) reduces the risk of recurrent cryptogenic stroke specifically in younger patients. The foramen ovale is a small hole in the fetal heart, located between the right and left atria (upper chambers). If you have a PFO and low blood oxygen levels or an unexplained stroke, you may need a procedure to close the hole.