Complications

Generally, a patent foramen ovale (PFO) doesn't cause complications. Some people with a PFO may have other heart defects.

Possible complications of patent foramen ovale may include:

• Low blood oxygen. Rarely, a patent foramen ovale can cause a significant amount of blood to bypass the lungs, causing low blood oxygen levels (hypoxemia).
• Stroke. Sometimes small blood clots in veins may travel to the heart. They may go through a patent foramen ovale and into the left side of the heart, where they can travel to the brain and block blood flow, causing an ischemic stroke.

Some studies have found that PFOs are more common in people with unexplained strokes and migraines with aura. However, more research is needed. Usually, there are other reasons for these conditions, and it's just a coincidence the person also has a PFO.