Narrowed aortic valve. Gross specimen of an aortic valve (central flaps). The aorta's lumen (central space) has been narrowed by deposits on the valve and vessel walls. The aortic wall forms the round structure enclosing the valve. The aortic valve lies between the aorta and the heart. It prevents the backflow of blood into the heart after it has been pumped out of the heart and into the aorta. The aorta is the main body artery that supplies blood from the heart to most parts of the body. This has occured in a patient who had Monckeberg's disease, a form of arteriosclerosis (artery hardening) that mostly affects the peripheral arteries in the elderly.