Atrial Septal Defect.

Atrial septal defects are common congenital heart defects, characterized by insufficient/absent tissue at the interatrial septum. An unrepaired defect may be associated with right heart volume overload, atrial arrhythmia or pulmonary arterial hypertension. The 3 major types of atrial septal defect are: ostium secundum defect, ostium primum defect, and sinus venosus. Characteristic physical findings include a midsystolic pulmonary flow or ejection murmur, accompanied by a fixed split-second heart sound. Small defects may spontaneously close; larger defects may persist and result in hemodynamic and clinical sequelae requiring percutaneous or surgical intervention. Severe pulmonary arterial hypertension is a contraindication to closure.