Patients who do need treatment may take medicines or have a percutaneous coronary intervention to close the PFO. In more serious cases, surgery may be needed.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. However, it may cause serious complications under certain circumstances. Most people with a patent foramen ovale don't need treatment. Discusses patent foramen ovale, which is an opening in the septum of the heart between the upper right and left chambers. Covers diagnosis and treatment. 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.