Coloured computed tomography (CT) scan of a 78 year old man's heart, showing atherosclerotic plaques (white) around the aortic valve (upper left). The aortic valve controls the flow of blood from the heart to the ascending aorta, the body's main artery. Atherosclerotic plaques are composed of fibrous and calcified material. They block blood vessels and impede the proper functioning of the heart's valves. Heart valve disease can be the result of an unhealthy lifestyle or a primary disease. Surgical valve replacement may be required.