Atrioventricular Septal Defect (AVSD)

Atrioventricular septal defect (AVSD) consists of a group of anomalies with the common main pathology of the absence of the atrioventricular (AV) septum associated with the abnormalities of the AV valves [1]. AVSD has been divided into the two main categories as the partial and complete forms and two other subtypes as the transitional (which is the subtype of partial AVSD) and intermediate (which is the subtype of complete AVSD). In complete AVSD, a primum ASD is concomitant with an inlet-type ventricular septal defect (VSD), and a common AV valve has only single annulus. In addition, transitional AVSD is used when a partial AVSD also has a small inlet-type VSD that is partially obstructed via chordal attachments to the intraventricular septum. Also, intermediate subtype of AVSD has separate right and left AV valve orifices even though having only one common annulus. These distinct orifices are referred to as right and left AV valve orifices rather than mitral and tricuspid [2, 3].