There are two types of holes which can be present between the upper chambers of the heart: an Atrial septal defect (ASD) and a patent foramen ovale (PFO). ASD is a birth defect with a gap in the heart's upper wall.This gap happens when the wall does not form right before birth. Generally an ASD hole is larger than a PFO. The larger the hole, the more likely symptoms are. Non-surgical closure of patent foramen ovale (PFO) and atrial septal defect (ASD) to repair these potentially life-threatening heart defects. Patent foramen ovale (PFO) and atrial septal defect (ASD) are holes in the wall that separates the two upper chambers of your heart. An ASD is a congenital heart defect, a condition that you are born with. PFOs can occur only after birth when the foramen ovale fails to close. An ASD closure device fixes an opening between your upper heart chambers (atria).