In the center an aortic valve with severe stenosis due to rheumatic heart disease. The valve is surrounded by the aorta. The pulmonary trunk is at the lower right. The right coronary artery (RCA) , cut lengthwise, is at the lower left. The left main coronary artery, also cut lengthwise, is on the right. Aortic stenosis is the narrowing of the exit of the left ventricle of the heart. 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 occur due to aortic stenosis the outcomes are worse. Loss of consciousness typically occurs with standing or exercising.