Introduction to Patent Foramen Ovale (PFO) Closure DevicesA patent foramen ovale (PFO) is a remaining opening in the septum between the two upper chambers of the heart, the left and right atria. Normally, this opening closes after birth, but for some people it remains unsealed. This allows blood to pass from the right atrium to the left atrium. While many people live normally with a PFO, in...