Atrioventricular Septal Defects

Abstract Atrioventricular septal defects (AVSDs), also referred to as atrioventricular canal defects, endocardial cushion defects, and atrioventricular communis, represent a spectrum of congenital heart disease. They are characterized by a variable deficiency of the atrioventricular septum and abnormal atrioventricular valves (AVVs). Classification of AVSDs includes incomplete (partial AVSDs or ostium primum atrial septal defects), transitional (intermediate), or complete. The latter are further subcategorized by the superior bridging leaflet using the Rastelli classification and also by the degree of balance. There is a strong association of AVSDs with Down syndrome and other cardiac anomalies. The pathophysiology is caused by left-to-right shunting across the septal defects and the degree of AVV regurgitation. The natural history leads to progressive congestive heart failure, late irreversible pulmonary hypertension, and, if left untreated, ultimately death. The goal of surgical repair of AVSDs is to create normal anatomy and physiology by septation of the heart with no residual intracardiac shunts and normal function of the AVV. Complete AVSDs can be repaired using either a single, modified single, or two-patch technique. Special considerations are made in the presence of a left superior vena cava, left AVV abnormalities, unbalanced AVSDs, or complete AVSD with tetralogy of Fallot. Overall survival is excellent following repair. However, significant morbidity may exist due to left AVV regurgitation and left ventricular outflow tract obstruction. Despite advances in care, these continue to be problematic and are the most common indications for reoperation.