The normal aortic valve consists of three leaflets. There are two ways that the aortic valve can malfunction. A stenotic (narrowed) aortic valve does not fully open as a result of disease affecting the ability of the valve leaflets to open, and an obstruction to the outflow of blood from the left ventricle is created.
In contrast, an insufficient aortic valve leaks, and allows backflow of blood from the aorta to the left ventricle during diastole. Asymptomatic patients with aortic stenosis or aortic insufficiency have a good prognosis. Once symptoms develop, the prognosis becomes poor and operation is usually performed.
Aortic stenosis is the most common reason for heart valve surgery.
The two most common causes of aortic stenosis in North America are degenerative calcification of the aortic valve and a congenital bicuspid aortic valve. Degenerative calcific aortic stenosis is a disease of aging and will become increasingly common as the United States population ages. The presence of obstruction to ventricular outflow causes hypertrophy (enlargement) of the left ventricular myocardium (heart muscle), which compensates for the outflow obstruction.
The three classic symptoms of aortic stenosis are:
Symptoms prompt rapid evaluation and operation (aortic valve replacement). Operation is highly effective at relieving outflow tract obstruction, preventing sudden death, improving left ventricular function, and alleviating symptoms.