overriding aortic valve MPheno.ontology Fyler:1432 DA overriding aorta MP:0000273 aortic dextroposition dextroposition of the aorta congenitally abnormal position of the aorta where the valve origin straddles the ventral septum and so receives ejected blood from the right ventricle as well as the left, frequently in conjunction with a ventricular septal defect abnormal heart and great artery attachment