coronary artery disease

The structure of the human heart. During an average lifetime, the human heart beats more than 2,000 million times and pumps 500 million l/110 million gal of blood. The average pulse rate is 70-72 beats per minute at rest for adult males, and 78-82 beats per minute for adult females.

A patient undergoing coronary artery surgery. The chest has been opened and the heart exposed. A heart-lung machine will take over the vital job of circulating oxygenated blood to the body while the heart is temporarily stopped. During this period, blockages in the coronary arteries will be bypassed using sections of vein taken from the patient's legs.

Condition in which the fatty deposits of atherosclerosis form in the coronary arteries that supply the heart muscle, narrowing them and restricting the blood flow.

These arteries may already be hardened (arteriosclerosis). If the heart's oxygen requirements are increased, as during exercise, the blood supply through the narrowed arteries may be inadequate, and the pain of angina results. A heart attack occurs if the blood supply to an area of the heart is cut off, for example because a blood clot (thrombus) has blocked one of the coronary arteries. The subsequent lack of oxygen damages the heart muscle (infarct), and if a large area of the heart is affected, the attack may be fatal. Coronary artery disease tends to run in families and is linked to smoking, lack of exercise, and a diet high in saturated (mostly animal) fats, which tends to increase the level of blood cholesterol. It is a common cause of death in many industrialized countries; older men are the most vulnerable group. The condition is treated with drugs or bypass surgery.

The American Heart Association reported that coronary heart disease caused 479,305 deaths in 2003 and is the single leading cause of death in the USA.

A number of interventions have been tried for coronary artery disease. Most effective is bypass surgery, an operation to replace narrowed sections of artery. The endoscopic procedure, known as percutaneous transluminal coronary angioplasty (PTCA), involves the use of a balloon-tipped catheter to widen the diseased vessel. PTCA is cheaper and less invasive than CABG, but in roughly a third of cases further surgery is required in six months.