Heart valve disease. Close-up of a gross clinical specimen of a sectioned heart showing an atheroma plaque (off-white, upper centre) on the mitral valve. Atheroma is a fatty deposit that forms on the inside of blood vessels and in the heart as part of atherosclerosis. Atheroma plaques narrow blood vessels, raising blood pressure, and can interfere with the functioning of the heart. Atherosclerosis is a disease linked to a fatty diet, inactivity, obesity and tobacco smoking. Valve disease such as this can be treated with valve replacement surgery, in which the diseased valve is removed and replaced by an artificial valve or a valve from a donor.