Aortic stenosis (AS) is the narrowing of the exit of the left ventricle of the heart such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse over time. Symptoms often come on gradually with a decreased ability to exercise often occurring first. If heart failure, loss of consciousness, or heart related chest pain occurs due to AS the outcomes are worse. Loss of consciousness typically occurs with standing or exercise. Signs of heart failure include shortness of breath especially with lying down, at night, and with exercise as well as swelling of the legs. Thickening of the valve without narrowing is known as aortic sclerosis.