Abnormal ascending aorta morphology Ascending aorta hypoplasia 2018-07-04T20:46:37Z Significant luminal narrowing of a long segment of or the entire ascending aorta. Coarctation of the aorta is defined as significant luminal narrowing of the aorta that produces hemodynamically significant obstruction to the flow of blood. This process may affect a short isolated segment of the aorta or a longer and more diffuse segment. When longer segments of the aorta are narrowed, the term hypoplasia is often used. Much less common than segmental coarctation, aortic hypoplasia has been described in all portions of the thoracic and abdominal aorta.