atrioventricular septal defect intermediate atrioventricular septal defect 2010-09-27T03:29:50Z Fyler:1121 MP:0010415 MPheno.ontology a type of atrioventricular septal defect in which a partial AVSD is present together with a small interventricular communication; a single valvar annulus is usually present where the anterior and posterior bridging leaflets fuse overlying the ventricular septum, with two distinct valvar components observed csmith intermediate AVC intermediate AVSD intermediate ECD intermediate atrioventricular canal defect intermediate endocardial cushion defect transitional common atrioventricular canal