Atrioventricular septal defect with ventricular imbalance

**Definition:** A congenital cardiac malformation that is a variant of an atrioventricular septal defect (atrioventricular canal defect) with one ventricle significantly larger than the other.

Additional information: unbalanced ventricular size and unbalanced relation of the common atrioventricular valve to the ventricles are to be distinguished by coding unbalanced ventricular size as 'Atrioventricular septal defect with ventricular imbalance' and the unbalanced relation of the common atrioventricular valve to the ventricles should also be coded as 'Common atrioventricular valve with unbalanced commitment of valve to ventricles'.