Aortic stenosis

Aortic stenosis (AS or AoS) is the narrowing of the outlet of the main pumping chamber of the heart, the left ventricle (LV) (where the aorta begins). If the narrowing is severe (very tight) the extra work required from the left ventricle to pump the blood against the increased resistance of a small orifice may cause (initially adaptive) thickening of the heart muscle, followed by severe weakness of the heart (heart failure). The most common form of AS involves the aortic valve, which separates the LV from the aorta. Much more rarely stenosis can occur below the aortic valve or above it. Aortic stenosis typically gets worse over time. Typical symptoms are shortness of breath on exertion, chest pain (angina) and dizziness or blackouts on exertion (syncope). They often come on gradually, with a decreased ability to exercise often occurring first. If heart failure, loss of consciousness, or heart related chest pain occur due to AS, the outcomes are worse, with mortality of 50% at 2-5 years in the absence of valve replacement. Loss of consciousness typically occurs with standing or exercising. Signs of heart failure include shortness of breath especially when lying down, at night, or with exercise, and swelling of the legs. Thickening of the aortic valve without obstruction to flow is known as aortic sclerosis. Causes include being born with a bicuspid aortic valve, and rheumatic fever; a normal valve may also harden over the decades due to calcification. A bicuspid aortic valve affects about one to two percent of the population. As of 2014 rheumatic heart disease mostly occurs in the developing world. Risk factors are similar to those of coronary artery disease and include smoking, high blood pressure, high cholesterol, diabetes, and being male. The aortic valve usually has three leaflets and is located between...