define incompetence

define stenosis

causes include the following
could be a congenital cause - as in you were anatomically born with it an example would be - bicuspid aortic valve
having a bicuspid valve can mean it may not close properly causing incompetence, and inc turbulance which could then cause calcification which then in turn leads to stenosis occuring
another cause is rheumatic fever, which can deform the valves, endocarditis, MI, Age
Cardiomyopathy (hypertrophic/dialated)
2 extremes