Death of part of the heart muscle caused by sudden interruption in the arterial blood supply to that section of the heart. It is caused by blockage of a coronary artery, almost always as a result of a coronary artery already constricted by atherosclerosis, in which even a small blood clot can then block the artery completely. Many patients who suffer cardiac infarction have angina pectoris, but it can occur without warning. Symptoms are the same as those of angina but more severe, and they persist for longer: severe, convulsive pain behind the breastbone, often radiating to left arm, neck and jaw, associated with nausea, vomiting, shortness of breath, sweating and acute feelings of anxiety. In angina pectoris the pain fades within minutes, but in cardiac infarction it can persist for hours, and anti-angina drugs have no effect. Death of heart muscle cells produces substances which show in blood tests; the greatest potential problem is serious rhythm disturbances, such as life-endangering ventricular fibrillation. Also so much muscle can die that the heart cannot maintain an adequate blood supply, and the patient dies as a result of low blood pressure. Cardiac infarction patients should be admitted to a cardiac ward in a hospital as soon as possible for the administration of painkillers and anticoagulants, and often drugs to combat rhythm disturbances. If no complications occur the patient can be discharged in a few days, and can start on a programme of rehabilitation.