atrioventricular septal defect AVSD 2010-09-27T02:50:46Z ECD The term name is common usage among cardiologists and refers to the specific state in the definition (abnormal communications); do not confuse with parent term. defects in the thin membranous structure between the right atrium and left ventricle that arise from faulty development of the embryonic endocardial cushions; the spectrum ranges from a primum atrial septal defect and cleft mitral valve, known as a partial atrioventricular septal defect (partial AVSD), to defects of both the primum atrial septum and inlet ventricular septum and the presence of a common atrioventricular valve, referred to as complete atrioventricular septal defect (complete AVSD) csmith MPheno.ontology MP:0010412 endocardial cushion defect AVCD Atrioventricular canal (endocardial cushion defect) atrioventricular canal defect Fyler:1100 AV septal defect AVC abnormal atrioventricular septum morphology