narrowing of the aorta above the aortic valve by a constricting ring or shelf, or by coarctation or hypoplasia of the ascending aorta.
su·pra·val·var ste·no·sis
(sū'pră-val'văr stĕ-nō'sis) Narrowing of the aorta above the aortic valve by a constricting ring or shelf, or by coarctation or hypoplasia of the ascending aorta.