Calcified heart valve. Coloured computed tomography (CT) scans of a section through the heart of a 67-year-old patient showing calcification of the aortic valve (round). The aortic valve lies between the left ventricle of the heart and the aorta. Calcification causes the valve to become hardened, leading to aortic valve stenosis (narrowing) whereby it fails to open fully. These scans were taken for pre-operative assessment prior to the replacement of valve.