Mayo Clinic Minute: What you need to know about patent foramen ovale

Before birth, oxygen travels from mom to baby. Oxygenated blood flows through a tiny flap from one side of the heart to the other. Dr. Peter Pollak, a Mayo Clinic cardiologist, says when you're born, you take your first breath, and that flap closes. And it seals in most people. But in approximately 1 out of 4 cases, the flap stays open.