What is coronary heart disease (CHD) ?

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Some 7 million Americans suffer from coronary heart disease (CHD), the most common form of heart disease. This type of heart disease is caused by a narrowing of the coronary arteries that feed the heart. CHD is the number one killer of both men and women in the U.S. Each year, more than 500,000 Americans die of heart attacks caused by CHD.

CHD is caused by a thickening of the inside walls of the coronary arteries. This thickening, called atherosclerosis, narrows the space through which blood can flow, decreasing and sometimes completely cutting off the supply of oxygen and nutrients to the heart. Atherosclerosis usually occurs when a person has high levels of cholesterol, a fat-like substance, in the blood. Cholesterol and fat, circulating in the blood, build up on the walls of the arteries. The buildup narrows the arteries and can slow or block the flow of blood. When the level of cholesterol in the blood is high, there is a greater chance that it will be deposited onto the artery walls. This process begins in most people during childhood and the teenage years, and worsens as they get older.

In addition to high blood cholesterol, high blood pressure and smoking also contribute to CHD. On the average, each of these doubles your chance of developing heart disease. Therefore, a person who has all three risk factors is eight times more likely to develop heart disease than someone who has none.

Chest pain (angina) or shortness of breath may be the earliest signs of CHD. A person may feel heaviness, tightness, pain, burning, pressure, or squeezing, usually behind the breastbone but sometimes also in the arms, neck, or jaws. These signs usually bring the patient to a doctor for the first time. Nevertheless, some people have heart attacks without ever having any of these symptoms. It is important to know that there is a wide range of severity for CHD. Some people have no symptoms at all, some have mild intermittent chest pain, and some have more pronounced and steady pain. Still others have CHD that is severe enough to make normal everyday activities difficult.

An examination for CHD may include the following tests:

  • An electrocardiogram (ECG or EKG) is a graphic record of the electrical activity of the heart as it contracts and rests. Abnormal heartbeats and some areas of damage, inadequate blood flow, and heart enlargement can be detected on the records.
  • A stress test (also called a treadmill test or exercise ECG) is used to record the heartbeat during exercise. This is done because some heart problems only show up when the heart is working hard. In the test, an ECG is done before, during, and after exercising on a treadmill; breathing rate and blood pressure may be measured as well. Exercise tests are useful but are not completely reliable; false positives (showing a problem where none exists) and false negatives (showing no problem when something is wrong) are fairly common.
  • Nuclear scanning is sometimes used to show damaged areas of the heart and expose problems with the heart’s pumping action. A small amount of radioactive material is injected into a vein, usually in the arm. A scanning camera records the nuclear material that is taken up by heart muscle (healthy areas) or not taken up (damaged areas).
  • Coronary angiography (or arteriography) is a test used to explore the coronary arteries. A fine tube (catheter) is put into an artery of an arm or leg and passed through the tube into the arteries of the heart. The heart and blood vessels are then filmed while the heart pumps. The picture that is seen, called an angiogram or arteriogram, will show problems such as a blockage caused by atherosclerosis.
    CHD is treated in a number of ways, depending on the seriousness of the disease. For many people, CHD is managed with lifestyle changes and medications. Others with severe CHD may need surgery. In any case, once CHD develops, it requires lifelong management.

Although great advances have been made in treating CHD, changing one’s habits remains the single most effective way to stop the disease from progressing.

If you know that you have CHD, changing your diet to one low in fat, especially saturated fat, and cholesterol will help reduce high blood cholesterol, a primary cause of atherosclerosis. In fact, it is even more important to keep your cholesterol low after a heart attack to help lower your risk of having another one. Eating less fat should also help you lose weight. If you are overweight, losing weight can help lower blood cholesterol and is the most effective lifestyle way to reduce high blood pressure, another risk factor for atherosclerosis and heart disease.

People with CHD can also benefit from exercise. Recent research has shown that even moderate amounts of physical activity are associated with lower death rates from CHD. However, people with severe CHD may have to restrict their exercise somewhat. If you have CHD, check with your doctor to find out what kinds of exercise are best for you.

Smoking is one of the three major risk factors for CHD. Quitting smoking dramatically lowers the risk of a heart attack and also reduces the risk of a second heart attack in people who have already had one.

Medications are prescribed according to the nature of the patient’s CHD and other problems. The symptoms of angina can generally be controlled by “beta-blocker” drugs that decrease the workload on the heart, by nitroglycerine and other “nitrates” and by “calcium-channel blockers” that relax the arteries, and by other classes of drugs. The tendency to form clots is reduced by aspirin or by other platelet inhibitory and anticoagulant drugs. Beta-blockers are given to decrease the recurrence of heart attack. For those with elevated blood cholesterol that is unresponsive to dietary and weight loss measures, cholesterol-lowering drugs may be prescribed, such as lovastatin, colestipol, cholestyramine, gemfibrozil, and niacin. Impaired pumping function of the heart may be treated with digitalis drugs or ACE inhibitors.

Many patients can control CHD with lifestyle changes and medication. Surgery may be recommended for patients who continue to have frequent or disabling angina despite the use of medications, or people who are found to have severe blockages in their coronary arteries.

Coronary angioplasty or balloon angioplasty begins with a procedure similar to that described under angiography. However, the catheter positioned in the narrowed coronary artery has a tiny balloon at its tip. The balloon is inflated and deflated to stretch or break open the narrowing and improve the passage for blood flow. The balloon-tipped catheter is then removed. Strictly speaking, angioplasty is not surgery. It is done while the patient is awake and may last 1 to 2 hours.

If angioplasty does not widen the artery or if complications occur, bypass surgery may be needed. In a coronary artery bypass operation, a blood vessel, usually taken from the leg or chest, is grafted onto the blocked artery, bypassing the blocked area. If more than one artery is blocked, a bypass can be done on each. The blood can then go around the obstruction to supply the heart with enough blood to relieve chest pain. Bypass surgery relieves symptoms of heart disease but does not cure it.

Usually you will need to make a number of changes in your lifestyle after the operation. If your normal lifestyle includes smoking, a high-fat diet, or no exercise, changes are advised.

Background information provided by: The National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892

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