A patent foramen ovale is a small, flaplike opening in the wall between the upper chambers of the heart. Most people will not have any signs or symptoms directly from PFO at all.Possible PFO symptoms include: Stroke. Symptoms of a PFO are often not noticeable. Some adults with PFOs also suffer from migraine headaches. Most people don't have symptoms. If you have PFO as an adult, there is a good chance that you won't even know. Most people don't have symptoms. Signs and symptoms of a PFO may not occur until early or middle adulthood and may even go undetected. In some cases, an exam following a stroke or transient ischemic attack may be the first time a PFO is discovered in the heart.