abnormal heart development abnormal fetal atrioventricular canal morphology MP:0006107 MPheno.ontology any structural anomaly of the common canal connecting the primordial atrium and ventricle during fetal development; the dorsal and ventral endocardial cushions develop in the walls of the common atrioventricular canal, grow toward each other and fuse, dividing the common atrioventricular canal into right and left atrioventricular canals and the atrioventricular septum