abnormal ascending aorta morphology ascending aorta hypoplasia 2010-09-30T09:27:38Z Fyler:2703 MP:0010469 MPheno.ontology csmith hypoplasia ascending aorta hypoplastic ascending aorta underdevelopment or reduced size of the portion of the aorta that arises from the base of the left ventricle and extends upward to the aortic arch and from which the coronary arteries arise, usually due to reduced cell number