atrioventricular septal defect (avsd) – partial

in this condition, the junction of the lower part of the atrial septum to the atrioventricular valve insertion is not intact. anatomically, there is always a common av valve although there are usually two orifices in a partial defect. it is commonly associated with down syndrome or is found in the setting of atrial isomerism, particularly left atrial isomerism. in its isolated form in a child with normal chromosomes, it may also be associated with left heart obstructive disease. it presents in infancy or early childhood with signs of a left to right shunt at the atrial level. surgical repair is usually satisfactory although mitral valve incompetence can be a difficult complication which may necessitate valve replacement. this is always problematic in children as long term anticoagulation therapy is required as well as subsequent valve replacement with growth of the child. associated left heart disease can complicate the outcome, even to the extent of leading to a one ventricle repair.