Paediatrics: Left to right shunt: atrial septal defect

Left to right shunt: atrial septal defect

ASD may be subtyped as ostium secundum or partial atrioventricular sep-tal defect (ostium primum).

Ostium secundum defect

This defect is in the region of the foramen ovale. The atrioventricular (AV) valves are normal. The defect is usually isolated, found incidentally, and 3 times more common in girls.

·Clinical features: most children are asymptomatic. ASDs may rarely result in heart failure.

·Prognosis: ostium secundum defects are well tolerated and symptoms and complications usually only present in 3rd decade or later.

·Treatment: ASD closure is required and advised for all patients, even if asymptomatic. This is achieved usually by insertion of an occlusion device at cardiac catheterization or by open heart surgery. Intervention should be performed in early childhood, before school entry.

Partial atrioventricular septal defect

This is the more serious ASD, affecting the endocardial cushion tissue that gives rise to the mitral and tricuspid valves. It is located in the lower atrial septum and is associated with a three leaflet mitral valve. These abnor-malities result in a left to right shunt with valve incompetence. AVSD are often seen in Down syndrome.

·Clinical features: most children with small defects are asymptomatic. Those with larger defects are predisposed to recurrent chest infections and to heart failure.

·Prognosis: depends on the degree of left to right shunt, pulmonary hypertension, and severity of mitral regurgitation. Without surgical repair congestive cardiac failure may develop in infancy/early childhood.

·Management: definitive treatment with surgical closure of the defect is indicated pre-school.