Final answer:
The bicuspid aortic valve, also known as the mitral or left atrioventricular valve, has two flaps and is crucial in heart function. Aortic stenosis can occur when this valve becomes rigid, which mainly affects older populations. Immediate surgery may be required if related structures are damaged.
Step-by-step explanation:
The bicuspid aortic valve is a variation of the normal aortic valve which typically has three cusps. Instead, a bicuspid valve has only two flaps or cusps. This valve is located at the opening between the left atrium and the left ventricle and is crucial for preventing blood from flowing backwards into the heart. Known as the mitral valve or left atrioventricular valve in a clinical setting, the structural difference in the bicuspid valve can sometimes lead to valve-related diseases such as stenosis, where the valve becomes rigid and may calcify.
Aortic stenosis, specifically, affects about 2 percent of those over 65, and the prevalence increases with age. Immediate surgical intervention may be necessary if the valve or its associated structures, such as the chordae tendineae or papillary muscles, fail due to a condition like a myocardial infarction. Conversely, at the base of the aorta lies the aortic semilunar valve, which serves to prevent backflow from the aorta into the ventricle and normally consists of three flaps.