Atrioventricular canal defect Unbalanced atrioventricular canal defect UMLS:C3280940 HP:0011579 Unbalanced atrioventricular septal defect Anatomic features of unbalanced atrioventricular septal defect (AVSD) include varying amounts of ventricular hypoplasia, as well as malalignment of the atrioventricular junction. In complete AVSD, the common AV valve can be situated either equally over the right and left ventricles (balanced) or unequally over the ventricles (unbalanced). 2012-04-08T11:02:44Z