The Structure of the Aortic Valve in Clinically Isolated Aortic Stenosis

The structure of the aortic valve at autopsy is described in 162 patients over 15 years of age with clinically isolated, severe valvular aortic stenosis with or without aortic regurgitation. The valves were congenitally unicuspid, unicommissural in 17 patients, congenitally bicuspid in 67, tricuspid in 71, and in seven the structure was uncertain. Thus, in at least 84 (52%) of the patients the valve was congenitally malformed at birth. It is proposed that minor aortic valvular cuspal inequality, also present from birth, may be an underlying malformation in some of the patients with tricuspid stenotic aortic valves. Degeneration or wear-and-tear from aging almost certainly explains aortic stenosis in most of the elderly patients. Although no patient had clinical evidence of mitral valvular dysfunction, the mitral leaflets were diffusely thickened by fibrous tissue in 26 of the 162 patients. Rheumatic disease is believed to be the cause of the valve involvement in 22 of them (the other four had congenitally bicuspid aortic valves). Rheumatic disease did not appear to be the cause of the aortic stenosis in the other 136 patients with anatomically normal mitral valves.