Enlarged heart. Coloured X-ray of the human chest showing left ventricular hypertrophy, the enlarge- ment of the left ventricle of the heart. The shadow of the enlarged heart (pink) protrudes abnormally towards the right of the image, that is, over the dark region of the left lung. Bones are blue; the diaphragm is brown at lower frame. Hypertrophy of the heart may be due to hyper- tension in which abnormally high blood pressure causes enlargement of the heart. Another cause is mitral incompetence, failure of the mitral heart valve to control the flow of blood into the left ventricle. Severe ventricular heart disease is associated with heart failure.