Understand what patent foramen ovale (PFO) is, how it affects stroke risk, and treatment options.
WHAT IS PATENT FORAMEN OVALE?
During development, prior to birth, a channel between the right and left sides of the heart called the foramen ovale, allows blood from veins to bypass the lungs. In about 33% of people, the foramen ovale does not close completely after birth. When the foramen ovale remains open, it is called a “patent foramen ovale” or a PFO. Typically, a PFO causes no problems. However, in some cases, it can allow a small amount of blood to pass from the right side of the heart to the left side of the heart.
This diagram shows an open foramen ovale before birth, a closed foramen ovale after birth, and a patent foramen ovale after birth.
HOW DOES A PFO AFFECT STROKE RISK?
Blood clots can develop in your veins for various reasons and travel to the right side of the heart. Normally, they are then pumped to the lungs, which act as a filter. However, a PFO can allow those clots to bypass the lungs and cross to the left side of the heart. From there, they can be pumped to the brain, causing a stroke.
Patients who have a PFO and have had a cryptogenic stroke may be at an increased risk for having a second stroke. In some patients, a second stroke can be prevented by having the PFO closed.