What Is a Patent Foramen Ovale (PFO)?
Before birth, there is an opening in the form of a tissue flap in the wall between the left atrium and right atrium (upper chambers) of the baby’s heart. This opening (“foramen ovale”) allows oxygenated blood from the mother to bypass the baby’s lungs, which do not function until birth. When the baby is born, this flap opening typically closes, and is completely sealed within a few months.
When the foramen ovale does not close completely, it is called a “patent foramen ovale” (PFO).
A patent foramen ovale occurs in about 25% to 30% percent of people (1 in 3 to 4 individuals).1
A PFO can allow a small amount of blood to pass from the right side of the heart to the left side of the heart. In the vast majority of individuals, a PFO causes no medical problems, and if discovered incidentally, requires no treatment or follow-up.