DIAGNOSIS AND SYMPTOMS

Coronary atherosclerosis usually takes many years to develop. Doctors have found coronary artery plaques in young soldiers killed in battle. But symptoms seldom occur until age 50 or later. In some cases, the first symptom is a heart attack or sudden death. However, a typical early symptom may be pain in the chest from exercising or some other activity that makes the heart work harder than usual. Doctors call such pain angina pectoris, or simply angina. The narrowed coronary arteries supply the heart with less oxygen, which may cause pain when the heart must work harder. After the exercising or other activity is stopped, the pain usually disappears. However, angina may worsen if left untreated. Patients may then suffer from frequent attacks, even when resting.

Physicians diagnose coronary artery disease by first listening to their patients tell of their general physical condition and past illnesses. They note any history of angina or heart attack and the presence of any risk factors. Physical examination may reveal other risk factors, such as high blood pressure or heart damage. Doctors use an instrument called an electrocardiograph to detect heart damage or disturbances of the heart rhythm. The instrument produces a record called an electrocardiogram (ECG), which displays the electrical activity of the heart muscle. The impulses are printed on moving paper that shows the heart's electrical activity as a series of wavy lines. Major waves represent contraction of the ventricles. Minor waves represent relaxation of the ventricles and contraction and relaxation of the atria. Most ECG's are taken with the patient lying down. But many physicians take a patient's ECG during exercise. Such a stress ECG shows whether a patient's heart--even if the patient has no chest pain--receives enough oxygen during vigorous exercise.

Doctors also use a method called radionuclide imaging to detect CAD. A doctor injects a radioactive element into a patient's bloodstream. The doctor can view the element on a screen as it spreads into the heart muscle. Areas that do not receive blood appear blank on the image. Doctors generally use radionuclide imaging with a stress ECG. If the usual diagnostic techniques leave doubt, physicians may perform cardiac catheterization followed by coronary angiography. They insert a long, flexible tube called a catheter through a large blood vessel, usually an artery in the area where the thigh and abdomen meet. They push the catheter up to where the coronary arteries begin and inject dye. The inside of the arteries can then be viewed and recorded on X-ray film called an angiogram. The test clearly shows the condition of the coronary arteries. Coronary angiography presents a small risk of injury or even death. Doctors therefore perform it only in difficult diagnostic cases.


If drugs fail to control coronary artery disease, doctors consider other techniques to correct the problem. In the easiest technique, coronary angioplasty or simply angioplasty, doctors insert a catheter with a deflated balloon attached into the narrowed area of the coronary artery. They then inflate the balloon, which pushes the blockage aside and enlarges the artery. Angioplasty works in about 85 per cent of patients at first. But in about a third of those patients, blockage returns within three months. For some patients, various methods may prolong the benefits of angioplasty. For example, intense beams of light from devices called lasers burn away new plaque deposits. Or the placement of tiny metal props in the artery may keep it open. Should catheter methods fail, most cardiologists suggest coronary artery bypass graft surgery. In bypass surgery, doctors first remove a short piece of a blood vessel, usually a vein from the patient's leg or from an artery in the chest.