After patent foramen ovale (PFO) closure, when to call, call 911 anytime you think you may need emergency care. Most people with a patent foramen ovale don't need treatment.The foramen ovale is a hole in the wall between the left and right atria of every human fetus. This hole allows blood to bypass the fetal lungs. Structural cardiology program in San Antonio. A patent foramen ovale (PFO) is a hole in the heart that didn't close the way it should after birth. A patent foramen ovale (PFO) is a small hole between the 2 upper chambers of the heart, the right and the left atrium. Lee PH, Song JK, Kim JS, et al. Patent foramen ovale (PFO) is implicated in the pathogenesis of a number of medical conditions but to date only one official position paper relat.