what causes the foramen ovale to close
Congenital Defect Closure for Atrial Septal Defects and Patent Foramen Ovale. A patent foramen ovale, or PFO, is an opening between the upper two chambers of the heart that failed to close after birth. This and other congenital defects, such as atrial septal defects, are sometimes referred to as a âhole in the heart.â Atrial septal defects exists in about 25 percent of the population.