Acquired Aortic Stenosis :  a) Rheumatic: In developing countries rheumatic aortic valve disease is more common than degenerative one. Mitral valve involvement is a common association. The valve may be predominantly stenotic with some degree of regurgitation.

b) Degenerative calcific aortic stenosis is more common in western countries.

Progressive degeneration and calcification leads to severe obstruction. Severe aortic regurgitation is less common than in rheumatic aortic valvar disease. This condition may be associated with mitral annular calcification.

Rarely aortic valve involvement is seen in rheumatoid a-thlitis, Paget's - disease of the bone and end stage renal disease.