Generally an ASD hole is larger than a PFO. The larger the hole, the more likely symptoms are.Patent foramen ovale closure is a procedure to close a hole in the heart. We use minimally invasive approaches to treat PFO without open-chest surgery. At Temple, ASD repair is often done via a catheter inserted into the heart, rather than open surgery. Atrial septal defect (ASD) closure is a procedure to close a hole in the heart. Interventional cardiologists use minimally invasive methods to ASD closure. Why do these birth defects occur? ASD is a development issue, leaving a lasting hole. Note how this appearance is different from that of a patent foramen ovale.