http://www.nhlbi.nih.gov/health/dci/Diseases/holes/holes_whatare.html
National Heart, Lung, and Blood Institute, National Institutes of Health
A hole in the heart (also called an atrial septal defect (ASD) or ventricular septal defect (VSD)) is a type of simple congenital (kon-JEN-i-tal) heart defect. This is a problem with the heart's structure that's present at birth. The publication links to more information about the defect, including types, causes, signs and symptoms, diagnosis, and treatments.