Atrioventricular septal defect with communication at atrial level and unrestrictive communication at ventricular level

**Definition:** A congenital cardiac malformation that is a variant of an atrioventricular septal defect (atrioventricular canal defect) with an interatrial communication just above the atrioventricular valve, an interventricular communication just below the atrioventricular valve, and varying degrees of malformation of the left ventricular component of the common atrioventricular valve.

Additional information: there is unrestrictive interventricular communication (no interventricular pressure gradient) and the bridging leaflets usually float to varying extent within the atrioventricular septal defect.