• atrial septal defect
• congenital heart disease surgery

Atrioventricular septal defects (AVSDs) are a spectrum of diseases affecting the atrioventricular septum and valves. Characteristic features are a common atrioventricular junction, deficient inlet ventricular septum, ostium pr imum atrial septal defect (ASD), abnormal left and right atrioventricular valves (AVV) and a ‘gooseneck’ deformity of the left ventricular outflow tract.1 In the complete form of AVSD, there is free interatrial and interventricular communication, with free-floating AVV leaflets. Transitional AVSD (tAVSD) is defined as AVSD associated with free interatrial communication, but a restrictive VSD component. Partial AVSD (pAVSD) refers to forms of AVSD with no interventricular communication, as the AVV leaflets are attached to the crest of the interventricular septum. In the past, this disease was referred to as ostium primum ASD, but this belies the other complex anatomy including the trifoliate left AVV and deficient ventricular septum. In these patients, the left AVV, while homologous to the mitral valve, markedly differs to the normal anatomy due to the small mural leaflet, and two bridging leaflets separated by a ‘cleft’ or ‘zone of apposition’, and for this reason should not be referred to as a mitral valve. Repair involves approximating the bridging leaflets to create a bifoliate valve, and applying a patch, usually autologous pericardium, to the ostium primum ASD.

Partial AVSDs are usually repaired in early childhood with excellent early and late survival, with nearly 95% of children alive at 30 years.2 However, it has become clear that these children have a high rate of reoperation, mostly due to left atrioventricular valve regurgitation (LAVVR), nearing 25% at 30 years.2 3 Traditionally, repair of pAVSD is performed at 2–4 years of age, unless signs of heart failure develop …