An atrial septal defect is a congenital heart defect where the wall between the right and left atria does not close properly, leaving a hole between the two atria.
Kurt R. Schumacher, MD, Pediatric Cardiology, University of Michigan Congenital Heart Center, Ann Arbor, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.