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 or PFO is a defect in the wall between the two 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. Most people with Patent Foramen Ovale do not need treatment. Most people with a patent foramen ovale don't need treatment. Treatment is a catheter procedure or surgery to close the opening in the heart. Patent foramen ovale (PFO) is a small hole between the upper right and left chambers (atria) of your heart. This hole may let blood flow between the atria. After the necessary form is filled out, please print, sign, and fax the form to the Medical Examiner's Office.