What is the definition or description of: aortic stenosis?

Aortic Stenosis: Aortic stenosis is the abnormal narrowing of the aortic valve. As the aortic valve develops progressive narrowing, the heart must work harder to contract and "squeeze" the blood through a smaller and smaller outflow orifice. This will eventually cause symptoms such as chest pain, dyspnea, or loss of consciousness. Severe aortic stenosis requires valve replacement.