Atrial Septal Defect
is one of the most common types of congenital heart defects, occurring in about 25% of children. Defect between the atria allows abnormal flow of oxygen-rich blood to leak into the oxygen-poor blood chambers in the heart. Small atrial septal defects usually spontaneously close in childhood. Large defects that do not close spontaneously may require percutaneous or surgical intervention to prevent further complications such as stroke, dysrhythmias, and pulmonary hypertension. The indication for closure of the defect is the presence of right ventricular volume overload.