Common atrioventricular junction without an atrioventricular septal defect

**Definition:** A congenital cardiac malformation in which there is a common atrioventricular junction without any communication at the level of the atrioventricular septum.

Additional information: this code should be used when there is a trifoliate left atrioventricular valve in the setting of a common atrioventricular junction with evidence of obliteration of the atrioventricular septal defect by valve or subvalvar tissue. This should be distinguished from a 'True cleft of anterior mitral leaflet', without evidence of a common atrioventricular junction. Additional defects in the atrial or ventricular septums that do not involve the atrioventricular septum are not excluded by this term and should be coded separately.