Heart disease. Three illustrations representing diseased conditions of the heart: ischaemia, myocardial infarction, pericarditis. At top, the heart muscle of the left ventricle is starved of oxygen (white) in ischaemia. This has been caused by narrowing of a coronary artery (yellow) and produces the condition of angina pectoris. At centre, a myocardial infarction (heart attack) has damaged some of the heart muscle, due to a clot seen in one of the narrowed coronary arteries. At bottom, the heart is enlarged with pericarditis. This is an inflammation of the sac surrounding the heart, and may follow the above diseases, or be due to viral infection, uraemia or cancer.