Patent foramen ovale (PFO) or hole in the heart, affects millions of people and can cause a stroke. Some studies have found that patent foramen ovales (PFOs) are more common in people with unexplained strokes and migraines with aura.This does not mean that everyone who has PFO will experience a stroke or mini-stroke. If the clot blocks a blood vessel in the brain, it can cause a stroke. These clots can also damage other organs, such as the heart or the kidneys. Most strokes do not result from a PFO. Even people who have a PFO often have strokes for other reasons. A patent foramen ovale is a small hole in the heart that may increase risk of stroke. Learn about how a PFO affect stroke risk. Therefore, large VSDs in adults are uncommon, but when they are present, can cause shortness of breath.