PFO treatment closes the Patent Foramen Ovale (PFO) through blood thinning medicines or a catheter-based procedure to close the hole. PFO closure may be achieved through open heart surgery or through a transcatheter procedure using an occlusion device.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. As the heart develops in the foetus, the primum and secundum septa grow and overlap. At birth, the PFO should close. Once the pulmonary circulation is established after birth, left atrial pressure increases, allowing functional closure of the foramen ovale. Los Angeles, California.