It is difficult to determine both the cause and severity of aortic valve lesions .(79) The most frequent causes of aortic stenosis are congenital aortic stenosis with unicuspid or bicuspid valve. The incidence and prevalence of the various etiologies of aortic stenosis have been influenced by the change in frequency of disease . (120) Valvular aortic stenosis is the most common cause of left ventricular out flow abstraction . Aortic stenosis may be due to congenital malformation of the valve or rheumatic fusion of the commissures . (119)
Congenital aortic stenosis
The term congenital aortic stenosis usually refers to valves that are stenotic at birth . Congenitally stenotic valves may be a commissural or unicommissural . Congenitally stenotic valves tend to calcify with advancing age .
Rheumatic aortic stenosis
Rheumatic aortic stenosis is the result of an inflammatory endocarditis , which causes adhesion of the leaflet commissures .(117) Rheumatic diseases of the aortic valve may cause pure aortic incompetence . (121).