Coronary Artery Disease

Definition

Coronary artery disease is a narrowing or blockage of the arteries and vessels that provide oxygen and nutrients to the heart. It is caused by atherosclerosis, an accumulation of fatty materials on the inner linings of arteries. The resulting blockage restricts blood flow to the heart. When the blood flow is completely cut off, the result is a heart attack.

Description

Coronary artery disease, also called coronary heart disease or heart disease, is the leading cause of death for both men and women in the United States. According to the American Heart Association, deaths from coronary artery disease have declined some since about 1990, but more than 40,000 people still died from the disease in 2000. About 13 million Americans have active symptoms of coronary artery disease.

Coronary artery disease occurs when the coronary arteries become partially blocked or clogged. This blockage limits the flow of blood from the coronary arteries, which are the major arteries supplying oxygen-rich blood to the heart. The coronary arteries expand when the heart is working harder and needs more oxygen. Arteries expand, for example, when a person is climbing stairs, exercising, or having sex. If the arteries are unable to expand, the heart is deprived of oxygen (myocardial ischemia ). When the blockage is limited, chest pain or pressure, called angina, may occur. When the blockage cuts off the flow of blood, the result is heart attack (myocardial infarction or heart muscle death).

Healthy coronary arteries are clean, smooth, and slick. The artery walls are flexible and can expand to let more blood through when the heart needs to work harder. The disease process in arteries is thought to begin with an injury to the linings and walls of the arteries. This injury makes them susceptible to atherosclerosis and blood clots (thrombosis).

Causes and symptoms

Coronary artery disease is usually caused by atherosclerosis. Cholesterol and other fatty substances accumulate on the inner wall of the arteries. They attract fibrous tissue, blood components, and calcium, and harden into artery-clogging plaques. Atherosclerotic plaques often form blood clots that also can block the coronary arteries (coronary thrombosis). Congenital defects and muscle spasms can also block blood flow. Recent research indicates that infection from organisms such as chlamydia bacteria may be responsible for some cases of coronary artery disease.

A number of major contributing factors increase the risk of developing coronary artery disease. Some of these can be changed and some cannot. People with more risk factors are more likely to develop coronary artery disease.

Major risk factors

Major risk factors significantly increase the chance of developing coronary artery disease. Those that cannot be changed are:

• Heredity—People whose parents have coronary artery disease are more likely to develop it. African Americans also are at increased risk because they experience a higher rate of severe hypertension than whites.
• Sex—Men are more likely to have heart attacks than women and to have them at a younger age. Over age 60, however, women have coronary artery disease at a rate equal to that of men.
• Age—Men who are 45 years of age and older and women who are 55 years of age and older are more likely to have coronary artery disease. Occasionally, coronary disease may strike a person in the 30s. Older people (those over 65) are more likely to die of a heart attack. Older women are twice as likely as older men to die within a few weeks of a heart attack.

Major risk factors that can be changed are:

• Smoking—Smoking increases both the chance of developing coronary artery disease and the chance of dying from it. Smokers are two to four times more likely than are non-smokers to die of sudden heart attack. They are more than twice as likely as non-smokers to have a heart attack. They also are more likely to die within an hour of a heart attack. Second hand smoke also may increase risk.
• High cholesterol—Dietary sources of cholesterol are meat, eggs, and other animal products. The body also produces it. Age, sex, heredity, and diet affect one's blood cholesterol. Total blood cholesterol is considered high at levels above 240 mg/dL and borderline at 200-239 mg/dL. High-risk levels of low-density lipoprotein (LDL cholesterol) begin at 130-159 mg/dL, depending on other risk factors. Risk of developing coronary artery disease increases steadily as blood cholesterol levels increase above 160 mg/dL. When a person has other risk factors, the risk multiplies.
• High blood pressure—High blood pressure makes the heart work harder and weakens it over time. It increases the risk of heart attack, stroke, kidney failure, and congestive heart failure. A blood pressure of 140 over 90 or above is considered high. As the numbers rise, high blood pressure goes from Stage 1 (mild) to Stage 4 (very severe). In combination with obesity, smoking, high cholesterol, or diabetes, high blood pressure raises the risk of heart attack or stroke several times.
• Lack of physical activity—Lack of exercise increases the risk of coronary artery disease. Even modest physical activity, like walking, is beneficial if done regularly.
• Diabetes mellitus—The risk of developing coronary artery disease is seriously increased for diabetics. More than 80% of diabetics die of some type of heart or blood vessel disease.

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but the degree of their significance is not known yet. Contributing risk factors are:

• Hormone replacement therapy—Evidence from a large trial called the Women's Health Initiative released in 2002 and 2003 found that hormone replacement therapy is a risk factor for coronary artery disease in postmenopausal women. The therapy was once thought to help protect women against heart disease, but in the trial, it was discovered that it was harmful to women with existing coronary artery disease.
• Obesity—Excess weight increases the strain on the heart and increases the risk of developing coronary artery disease even if no other risk factors are present. Obesity increases blood pressure and blood cholesterol and can lead to diabetes.
• Stress and anger—Some scientists believe that stress and anger can contribute to the development of coronary artery disease and increase the blood's tendency to form clots (thrombosis). Stress, the mental and physical reaction to life's irritations and challenges, increases the heart rate and blood pressure and can injure the lining of the arteries. Evidence shows that anger increases the risk of dying from heart disease. The risk of heart attack is more than double after an episode of anger.

Chest pain (angina) is the main symptom of coronary heart disease but it is not always present. Other symptoms include shortness of breath, and chest heaviness, tightness, pain, a burning sensation, squeezing, or pressure either behind the breastbone or in the arms, neck, or jaws. Many people have no symptoms of coronary artery disease before having a heart attack; 63% of women and 48% of men who died suddenly of coronary artery disease had no previous symptoms of the disease, according to the American Heart Association.

Diagnosis

Diagnosis begins with a visit to the physician, who will take a medical history, discuss symptoms, listen to the heart, and perform basic screening tests. These tests will measure weight, blood pressure, blood lipid levels, and fasting blood glucose levels. Other diagnostic tests include resting and exercise electrocardiogram, echocardiography, radionuclide scans, and coronary angiography. The treadmill exercise (stress) test is an appropriate screening test for those with high risk factors even when they feel well.

An electrocardiogram (ECG) shows the heart's activity and may reveal a lack of oxygen (ischemia). Electrodes covered with conducting jelly are placed on the patient's chest, arms, and legs. They send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder that traces them on paper. The test takes about 10 minutes and is performed in a physician's office. A definite diagnosis cannot be made from electrocardiography. About 50% of patients with significant coronary artery disease have normal resting electrocardiograms. Another type of electrocardiogram, known as the exercise stress test, measures how the heart and blood vessels respond to exertion when the patient is exercising on a treadmill or a stationary bike. This test is performed in a physician's office or an exercise laboratory. It takes 15-30 minutes. It is not perfectly accurate. It sometimes gives a normal reading when the patient has a heart problem or an abnormal reading when the patient does not.

If the electrocardiogram reveals a problem or is inconclusive, the next step is exercise echocardiography or nuclear scanning (angiography). Echocardiography, cardiac ultrasound, uses sound waves to create an image of the heart's chambers and valves. A technologist applies gel to a hand-held transducer, then presses it against the patient's chest. The heart's sound waves are converted into an image that can be displayed on a monitor. It does not reveal the coronary arteries themselves, but can detect abnormalities in heart wall motion caused by coronary disease. Performed in a cardiology outpatient diagnostic laboratory, the test takes 30-60 minutes.

Radionuclide angiography enables physicians to see the blood flow of the coronary arteries. Nuclear scans are performed by injecting a small amount of radiopharmaceutical such as thallium into the bloodstream. A device that uses gamma rays to produce an image of the radioactive material (gamma camera) records pictures of the heart. Radionuclide scans are not dangerous. The radiation exposure is about the same as that in a chest x ray. The tiny amount of radioactive material used disappears from the body in a few days. Radionuclide scans cost about four times as much as exercise stress tests but provide more information.

In radionuclide angiography, a scanning camera passes back and forth over the patient who lies on a table. Radionuclide angiography is usually performed in a hospital's nuclear medicine department and takes 30-60 minutes. Thallium scanning usually is done in conjunction with an exercise stress test. When the stress test is finished, thallium or sestamibi is injected. The patient resumes exercise for one minute to absorb the thallium. For patients who cannot exercise, cardiac blood flow and heart rate may be increased by intravenous dipyridamole (Persantine) or adenosine. Thallium scanning is done twice, immediately after injecting the radiopharmaceutical and again four hours (and maybe 24 hours) later. It is usually performed in a hospital's nuclear medicine department. Each scan takes 30-60 minutes.

Coronary angiography is the most accurate method for making a diagnosis of coronary artery disease, but it also is the most invasive. It is a form of cardiac catheterization that shows the heart's chambers, great vessels, and coronary arteries using x-ray technology. During coronary angiography the patient is awake but sedated. ECG electrodes are placed on the patient's chest and an intravenous line is inserted. A local anesthetic is injected into the site where the catheter will be inserted. The cardiologist inserts a catheter into a blood vessel and guides it into the heart. A contrast dye is injected to make the heart visible on x-ray cinematography. Coronary angiography is performed in a cardiac catheterization laboratory either in an outpatient or inpatient surgery unit. It takes from 30 minutes to two hours.

Treatment

Coronary artery disease can be treated many ways. The choice of treatment depends on the severity of the disease. Treatments include lifestyle changes and drug therapy, percutaneous transluminal coronary angioplasty, and coronary artery bypass surgery. Coronary artery disease is a chronic disease requiring lifelong care. Angioplasty or bypass surgery is not a cure.

People with less severe coronary artery disease may gain adequate control through lifestyle changes and drug therapy. Many of the lifestyle changes that prevent disease progression—a low-fat, low-cholesterol diet, weight loss if needed, exercise, and not smoking—also help prevent the disease from developing.

Drugs such as nitrates, beta-blockers, and calcium-channel blockers relieve chest pain and complications of coronary artery disease, but they cannot clear blocked arteries. Nitrates (nitroglycerin) improve blood flow to the heart. Beta-blockers (acebutelol, propranolol) reduce the amount of oxygen required by the heart during stress. One type of calcium-channel blocker (verapamil, diltiazem hydrochloride) helps keep the arteries open and reduces blood pressure. Aspirin helps prevent blood clots from forming on plaques, reducing the likelihood of a heart attack. Cholesterol-lowering medications are also indicated in most cases.

Percutaneous transluminal coronary angioplasty and bypass surgery are procedures that enter the body (invasive procedures) to improve blood flow in the coronary arteries. Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty, is a non-surgical procedure. A catheter tipped with a balloon is threaded from a blood vessel in the thigh into the blocked artery. The balloon is inflated, compressing the plaque to enlarge the blood vessel and open the blocked artery. The balloon is deflated, and the catheter is removed. Coronary angioplasty is performed in a hospital and generally requires a stay of one or two days. Coronary angioplasty is successful about 90% of the time, but for one-third of patients, the artery narrows again within six months. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.

In coronary artery bypass surgery, a healthy artery or vein from an arm, leg, or chest wall is used to build a detour around the coronary artery blockage. The healthy vessel then supplies oxygen-rich blood to the heart. Bypass surgery is major surgery. It is appropriate for those patients with blockages in two or three major coronary arteries, those with severely narrowed left main coronary arteries, and those who have not responded to other treatments. It is performed in a hospital under general anesthesia. A heart-lung machine is used to support the patient while the healthy vein or artery is attached past the blockage to the coronary artery. About 70% of patients who have bypass surgery experience full relief from angina; about 20% experience partial relief. Only about 3-4% of patients per year experience a return of symptoms. Survival rates after bypass surgery decrease over time. At five years after surgery, survival expectancy is 90%; at 10 years about 80%, at 15 years about 55%, and at 20 years about 40%.

Various semi-experimental surgical procedures for unblocking coronary arteries are currently being studied. Atherectomy is a procedure in which the surgeon shaves off and removes strips of plaque from the blocked artery. In laser angioplasty, a catheter with a laser tip is inserted into the affected artery to burn or break down the plaque. A metal coil called a stent can be implanted permanently to keep a blocked artery open. Stenting is becoming more common.

Alternative treatment

Natural therapies may reduce the risk of certain types of heart disease, but once symptoms appear, conventional medical attention is necessary. A healthy diet (including cold-water fish as a source of essential fatty acids) and exercise, important components of conventional prevention and treatment strategies, also are emphasized in alternative approaches to coronary artery disease. Herbal medicine offers a variety of remedies that may have a beneficial effect on coronary artery disease. For example, ginger (Zingiber officinale ) may help reduce cholesterol. Garlic (Allium sativum ), ginger, and hot red or chili peppers all are circulatory enhancers that can help prevent blood clots. Yoga and other bodywork, massage, relaxation therapies, and talking therapies also may help prevent coronary artery disease and stop, or even reverse, the progression of atherosclerosis. Vitamin and mineral therapy to reduce, reverse, or protect against coronary artery disease include chromium; calcium and magnesium; B-complex vitamins ; the antioxidant vitamins C and E; selenium; and zinc. Traditional Chinese medicine may recommend herbal remedies, massage, acupuncture, and dietary modification. However, studies released in 2003 showed that vitamins C and E fell short of claims that they helped narrow blockage caused by coronary artery disease. In fact, high doses of the vitamins should be avoided.

Prognosis

In many cases, coronary artery disease can be successfully treated. Advances in medicine and healthier lifestyles have caused a substantial decline in death rates from coronary artery disease since the mid-1980s. New diagnostic techniques enable doctors to identify and treat coronary artery disease in its earliest stages. New technologies and surgical procedures have extended the lives of many patients who would otherwise have died. Research on coronary artery disease continues.

Prevention

A healthy lifestyle can help prevent coronary artery disease and help keep it from progressing. A heart-healthy lifestyle includes eating right, regular exercise, maintaining a healthy weight, no smoking, moderate drinking, no recreational drugs, controlling hypertension, and managing stress. Cardiac rehabilitation programs are excellent to help prevent recurring coronary problems for people who are at risk and who have had coronary events and procedures.

Eating right

A healthy diet includes a variety of foods that are low in fat, especially saturated fat, low in cholesterol, and high in fiber. It includes plenty of fruits and vegetables, nuts and whole grains, and limited sodium. Some foods are low in fat but high in cholesterol and some are low in cholesterol but high in fat. Saturated fat raises cholesterol and, in excessive amounts, increases the amount of the clot-forming proteins in blood. Polyunsaturated and monounsaturated fats are good for the heart. Fat should comprise no more than 30% of total daily calories.

Cholesterol, a waxy substance containing fats, is found in foods such as meat, eggs, and other animal products. It also is produced in the liver. Soluble fiber can help lower cholesterol. Dietary cholesterol should be limited to about 300 milligrams per day. Many popular lipid-lowering drugs can reduce LDL cholesterol by an average of 25-30% when used with a low-fat, low-cholesterol diet.

Fruits and vegetables are rich in fiber, vitamins, and minerals. They are low calorie and nearly fat free. Vitamin C and beta-carotene, found in many fruits and vegetables, keep LDL cholesterol from turning into a form that damages coronary arteries.

Excess sodium can increase the risk of high blood pressure. Many processed foods contain large amounts of sodium. Daily intake should be limited to about 2,400 milligrams, about the amount in a teaspoon of salt.

The "Food Guide" Pyramid developed by the U.S. Departments of Agriculture and Health and Human Services provides easy-to-follow guidelines for daily heart-healthy eating. It recommends 6 to 11 servings of bread, cereal, rice, and pasta; three to five servings of vegetables; two to four servings of fruit; two to three servings of milk, yogurt, and cheese; and two to three servings of meat, poultry, fish, dry beans, eggs, and nuts. Fats, oils, and sweets should be used sparingly. Canola and olive oil are better for the heart than other cooking oils. Coronary patients should be on a strict diet. In 2003, the American Heart Association advised a diet rish in fatty fish such as salmon, herring, trout, or sardines. If people cannot eat daily servings of these fish, the association recommends three fish oil capsules per day.

Regular exercise

Aerobic exercise can lower blood pressure, help control weight, and increase HDL ("good") cholesterol. It may keep the blood vessels more flexible. The Centers for Disease Control and Prevention and the American College of Sports Medicine recommend moderate to intense aerobic exercise lasting about 30 minutes four or more times per week for maximum heart health. Three 10-minute exercise periods also are beneficial. Aerobic exercise—activities such as walking, jogging, and cycling—uses the large muscle groups and forces the body to use oxygen more efficiently. It also can include everyday activities such as active gardening, climbing stairs, or brisk housework. People with coronary artery disease or risk factors should consult a doctor before beginning an exercise program.

Maintaining a desirable body weight

About one-fourth of all Americans are overweight and nearly one-tenth are obese, according to the Surgeon General's Report on Nutrition and Health. People who are 20% or more over their ideal body weight have an increased risk of developing coronary artery disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost HDL cholesterol. It also may reduce blood pressure. Eating right and exercising are two key components of losing weight.

Avoiding recreational drugs

Smoking has many adverse effects on the heart. It increases the heart rate, constricts major arteries, and can create irregular heartbeats. It raises blood pressure, contributes to the development of plaque, increases the formation of blood clots, and causes blood platelets to cluster and impede blood flow. Heart damage caused by smoking can be repaired by quitting. Even heavy smokers can return to heart health. Several studies have shown that ex-smokers face the same risk of heart disease as non-smokers within five to 10 years after quitting.

Drink in moderation. Modest consumption of alcohol may actually protect against coronary artery disease because alcohol appears to raise levels of HDL cholesterol. The American Heart Association defines moderate consumption as one ounce of alcohol per day, roughly one cocktail, one 8-ounce glass of wine, or two 12-ounce glasses of beer. However, even moderate drinking can increase risk factors for heart disease for some people (by raising blood pressure, for example). Excessive drinking always is bad for the heart. It usually raises blood pressure and can poison the heart and cause abnormal heart rhythms or even heart failure.

Do not use other recreational drugs. Commonly used recreational drugs, particularly cocaine and "crack," can seriously harm the heart and should never be used.

Seeking treatment for hypertension

High blood pressure, one of the most common and serious risk factors for coronary artery disease, can be controlled completely through lifestyle changes and medication. Moderate hypertension can be controlled by reducing dietary intake of sodium and fat, exercising regularly, managing stress, abstaining from smoking, and drinking alcohol in moderation. People for whom these changes do not work or people with severe hypertension may be helped by many categories of medication.

KEY TERMS

Atherosclerosis— A process in which the walls of the coronary arteries thicken due to the accumulation of plaque in the blood vessels. Atherosclerosis is the cause of coronary artery disease.

Angina— Chest pain that happens when diseased blood vessels restrict the flow of blood to the heart. Angina often is the first symptom of coronary artery disease.

Beta-blocker— A drug that blocks some of the effects of fight-or-flight hormone adrenaline (epinephrine and norepinephrine), slowing the heart rate and lowering the blood pressure.

Calcium-channel blocker— A drug that blocks the entry of calcium into the muscle cells of small blood vessels (arterioles) and keeps them from narrowing.

Coronary arteries— The main arteries that provide blood to the heart. The coronary arteries surround the heart like a crown, coming out of the aorta, arching down over the top of the heart, and dividing into two branches. These are the arteries in which coronary artery disease occurs.

HDL cholesterol— High-density lipoprotein cholesterol is a component of cholesterol that helps protect against heart disease. HDL is nicknamed "good" cholesterol

LDL cholesterol— Low-density lipoprotein cholesterol is the primary cholesterol molecule. High levels of LDL increase the risk of coronary heart disease. LDL is nicknamed "bad" cholesterol.

Plaque— A deposit of fatty and other substances that accumulate in the lining of the artery wall.

Triglyceride— A fat that comes from food or is made from other energy sources in the body. Elevated triglyceride levels contribute to the development of atherosclerosis.

Managing stress

Everyone experiences stress. Stress sometimes can be avoided and when it is inevitable, it can be controlled. It is particularly important for those at risk for heart disease. A 2003 report showed that middle-aged men with high anxiety were less likely to adhere to heart healthy lifestyle practices. Techniques for controlling stress include: taking life more slowly, spending more time with family and friends, thinking positively, getting enough sleep, exercising, and practicing relaxation techniques.

Resources

BOOKS

Notelovitz, Morris, and Diana Tonnessen. The Essential Heart Book for Women. New York: St. Martin's Press, 1996.

Texas Heart Institute. "Coronary Artery Disease, Angina, and Heart Attacks." In Texas Heart Institute Heart Owner's Handbook. New York: JohnWiley & Sons, 1996.

PERIODICALS

"For Fighting Heart Disease, Vitamins C and E Fall Short." Tufts University Health and Nutrition Newsletter January 2003: 2.

Jancin, Bruce. "High Anxiety Level Predicts Heart-unhealthy Lifestyle." Internal Medicine News March 15, 2003: 25.

"Optimal Diets for Prevention of CHD." Clinical Cardiology Alert February 2003.

Wellbery, Caroline. "No HRT or Antioxidants in Women with Coronary Disease." American Family Physician March 15, 2003: 1371.

Zoler, Michael L. "Heart Association Advocates Fish Oil Supplements." Family Practice News January 15, 2003: 6.

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave, Dallas, TX 75231. (214) 373-6300. 〈http://www.americanheart.org〉.

National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. 〈http://www.nhlbi.nih.gov〉.

Texas Heart Institute. Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. 〈http://www.tmc.edu/thi〉.

Coronary Artery Disease

Definition

Coronary artery disease is a stenosis (narrowing) or blockage of the arteries and vessels that provide oxygenated blood to the heart. It is caused by atherosclerosis (hardening of the arteries), an accumulation of fatty plaque on the inner linings of arteries. The resulting blockage restricts blood flow through the coronary arteries. When blood flow is completely cut off, the result is myocardial infarction (heart attack).

Description

Coronary artery disease, also called coronary heart disease or atherosclerotic heart disease, is the leading cause of death for men and women in the United States. According to the American Heart Association, in 1998 one in every five deaths in the United States was caused by coronary artery disease. About every 29 seconds one American will have a heart attack; about every minute one American will die from a heart attack. Fourteen million Americans have active symptoms of coronary artery disease. Many millions more have asymptomatic (silent) coronary disease, the first indication of which can be sudden death.

Coronary artery disease occurs when the coronary arteries become partially blocked or clogged, thereby depriving the heart muscle of oxygen (myocardial ischemia). When the blockage is temporary or partial, angina (chest pain or pressure) may occur. When the blockage completely and suddenly cuts off the flow of blood, the result is myocardial infarction.

Healthy coronary arteries are clean, smooth, and slick. The artery walls are flexible and can expand to let more blood through when the heart needs to work harder. Atherosclerosis is thought to begin with an injury to the linings of the inner walls of the arteries. This injury makes them susceptible to atherosclerosis and thrombosis (blood clots).

Causes and symptoms

Coronary artery disease is usually caused by atherosclerosis. Cholesterol and other fatty substances accumulate on the inner wall of the arteries. This attracts fibrous tissue, blood components, and calcium, which harden into flow-obstructing plaques. If a blood clot suddenly forms on one of these plaques it can convert a partial obstruction to a total occlusion. This is known as coronary thrombosis. Congenital defects and spasms of a coronary artery may also block blood flow. There is evidence that infection from organisms such as chlamydia bacteria may be responsible for some cases of coronary artery disease.

A number of major contributing factors increase the risk of developing coronary artery disease. Some risk factors can be modified and others cannot. Persons with more of these risk factors are at greater risk of developing coronary artery disease.

Major risk factors

Major risk factors significantly increase the chance of developing coronary artery disease. Risk factors that cannot be changed include:

• Heredity. People whose parents have coronary artery disease, particularly those who develop it at younger ages, are more likely to be diagnosed with it. African Americans are also at increased risk because they experience a higher rate of severe hypertension than whites.
• Gender. Men under the age of 60 years of age are more likely to have myocardial infarctions than women of the same age. Over age 60, however, women have coronary artery disease at a rate equal to that of men.
• Age. Men over age 45 and women over age 55 years are more likely to have coronary artery disease. Occasionally, coronary disease affects individuals in the 30s. Older adults (those over 65) are more likely to die of a myocardial infarction. Older women are twice as likely as older men to die within a few weeks of a myocardial infarction.

Major risk factors that can be changed are:

• Smoking. Smoking greatly increases both the risk of developing coronary artery disease and resulting mortality. Smokers have two to four times the risk of non-smokers for sudden cardiac death and are more than twice as likely to have a myocardial infarction. They are also more likely to die within an hour of a heart attack. Second-hand smoke may also increase risk.
• High cholesterol. Cholesterol is produced by the body, and obtained from eating animal products such as meat, eggs, milk, and cheese. Age, gender, heredity, and diet affect cholesterol level. Risk of developing coronary artery disease increases as blood cholesterol levels increase. When combined with other factors, the risk is even greater. Total cholesterol of 240 mg/dL or more poses a high risk, and 200-239 mg/dL a borderline high risk. For LDL (low-density lipoprotein) cholesterol, high risk starts at 130-159 mg/dL, depending on other risk factors. Low levels of HDL (high-density lipoprotein) increases the risk of coronary disease; high HDL protects against it.
• Hypertension (high blood pressure ). High blood pressure makes the heart work harder, and over time, weakens it. It increases the risk of myocardial infarction, stroke, kidney failure, and congestive heart failure. Blood pressure of 140 over 90 or above is considered high. When hypertension is combined with obesity, smoking, high cholesterol, or diabetes, the risk of myocardial infarction or stroke increases several times.
• Sedentary lifestyle and lack of physical activity. Inactivity increases the risk of coronary artery disease. Even modest physical activity is beneficial if done regularly.
• Diabetes mellitus. The risk of developing coronary artery disease is significantly increased for diabetics. More than 80% of diabetics die of some type of cardiovascular disease.

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but their precise contribution to the development of disease is not known yet. Contributing risk factors are:

• Obesity. Excess weight increases the strain on the heart and increases the risk of developing coronary artery disease, even if no other risk factors are present. Obesity increases both blood pressure and blood cholesterol, and can lead to diabetes.
• Stress and anger. Stress and anger can produce physiological changes that contribute to the development of coronary artery disease, in part by increasing the risk of thrombosis. Stress, the mental and physical reaction to life's irritations and challenges, increases heart rate and blood pressure and can injure the lining of the arteries. Evidence shows that anger increases the risk of dying from heart disease. The risk of heart attack is more than double after an episode of anger.

Angina (chest pain) is the main symptom of coronary heart disease but it is not always present. Symptoms of angina typically include chest pain that may be described as heaviness, tightness, a burning sensation, squeezing, or pressure behind the breastbone. This pain may radiate to the left arm, neck, or jaw. Many people have no symptoms of coronary artery disease before having a heart attack; 63% of women and 48% of men who died suddenly of coronary artery disease had no previous symptoms of the disease, according to the American Heart Association.

Diagnosis

The diagnosis of coronary artery disease is made by the physician after a medical history, physical examination, and basic screening tests have been performed. The diagnostic work-up includes evaluation of body weight, blood pressure, blood lipid levels, and fasting blood glucose levels. Other diagnostic tests include resting and exercise electrocardiogram (ECG), echocardiography, radionuclide scans, and coronary angiography. A treadmill exercise (stress) test also may be used as a screening test for patients with significant risk factors but are asymptomatic.

An ECG may reveal if a patient has had a previous myocardial infarction (MI) or is having a MI. An ECG taken on a patient with coronary artery disease who is not having chest pain during the ECG and has not had a prior MI may be completely normal. An ECG technician places electrodes on the patient's chest, arms, and legs. These electrodes send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder that traces them on paper. The test takes about 10 minutes and is performed in a physician's office. A definite diagnosis cannot be made from electrocardiography. About 50% of patients with significant coronary artery disease have normal resting electrocardiograms. Another type of electrocardiogram, known as an exercise stress test, measures how the heart and blood vessels respond to exertion when the patient is exercising on a treadmill or a stationary bike. This test is performed in a physician's office or an exercise laboratory. It takes 15-30 minutes. Like many medical tests, it does not have 100% accuracy. It sometimes gives a normal reading when the patient has a heart problem or an abnormal reading when the patient does not.

If the electrocardiogram reveals a problem or is inconclusive, the next step is exercise echocardiography or nuclear myocardial scanning (radionuclide angiography). Echocardiography, cardiac ultrasound, uses sound waves to create an image of the heart's chambers and valves. A technician presses a handheld transducer against the patient's chest to obtain an image that can be displayed on a monitor. It does not visualize the coronary arteries, but can detect abnormalities in heart wall motion caused by coronary disease. Performed in a cardiology outpatient diagnostic laboratory, the test takes about 30-60 minutes.

Nuclear myocardial scanning enables physicians to see if the myocardium (heart muscle) is being adequately perfused by the coronary arteries. Performed by radiologists and radiology technicians, nuclear scans involve injecting a small amount of radiopharmaceutical, such as thallium or sestamibi, into a vein. A camera that uses gamma rays to produce an image of the radioactive material records pictures of the heart. A radionuclide scan is comparable, in terms of radiation exposure, to a chest x ray. The tiny amount of radioactive material used disappears from the body in a few days. Radionuclide scans cost about four times as much as exercise stress tests but provide more information.

In nuclear myocardial scanning, a camera passes back and forth over the patient who lies on a table. Usually performed in a hospital's nuclear medicine department, the procedure takes 30-60 minutes.

Nuclear myocardial scanning is usually performed in conjunction with an exercise stress test. When the stress test is completed, thallium or sestamibi is injected. The patient resumes exercise for one minute to absorb the thallium. For patients who cannot exercise, cardiac blood flow and heart rate may be increased by intravenous dipyridamole (Persantine) or adenosine. Thallium or sestamibi scanning is done twice, immediately after injecting the radiopharmaceutical and again four hours (and maybe 24 hours) later. Usually performed in a hospital's nuclear medicine department, each scan takes about 30-60 minutes.

Coronary angiography is the gold standard (most accurate method) for establishing the diagnosis of coronary artery disease, but it is also the most invasive. During coronary angiography the patient is awake but sedated. ECG electrodes are placed on the patient's chest and an intravenous line is inserted. A local anesthetic is injected into the site where the catheter will be inserted. The invasive cardiologist inserts a catheter into a groin artery and guides it into the aorta. A contrast dye is injected directly into the coronary arteries to determine whether they are obstructed. Coronary angiography is performed in a cardiac catheterization laboratory either in an outpatient or inpatient surgery unit. It takes from 30 minutes to two hours.

Treatment

Coronary artery disease can be treated many ways. The choice of treatment depends on the severity of the disease. Treatments include lifestyle changes and drug therapy, percutaneous transluminal coronary angioplasty, and coronary artery bypass surgery. Coronary artery disease is a chronic disease requiring lifelong care. Angioplasty or bypass surgery is not a "cure."

Patients with less severe coronary artery disease may gain adequate control through lifestyle changes and drug therapy. Many of the lifestyle changes that prevent disease progression—a low-fat, low-cholesterol diet, weight loss if needed, exercise, and not smoking—also help prevent the disease from developing.

Drugs such as nitrates, beta-blockers, and calcium-channel blockers relieve chest pain and complications of coronary artery disease, but they cannot clear blocked arteries. Nitrates (nitroglycerin) improve blood flow to the heart. Beta-blockers (acebutelol, propranolol) reduce the amount of oxygen required by the heart during stress. One type of calcium-channel blocker (verapamil, diltiazem hydrochloride) helps keep the arteries open and reduces blood pressure. Aspirin helps prevent blood clots from forming on plaques, reducing the likelihood of myocardial infarction. Cholesterol-lowering medications are also indicated in most cases.

Percutaneous transluminal coronary angioplasty and bypass surgery are invasive procedures to improve blood flow in the coronary arteries. Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty or PTCA, is a non-surgical procedure. A catheter tipped with a balloon is threaded through an artery in the groin into the blocked coronary artery. The balloon is inflated, compressing the plaque to enlarge the blood vessel and open the blocked artery. The balloon is deflated, and the catheter is removed. Coronary angioplasty is performed by an invasive cardiologist in a hospital and generally requires a stay of one or two days. Coronary angioplasty is successful about 90% of the time, but onethird of the time the artery restenoses (narrows again) within six months. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.

In coronary artery bypass surgery, a healthy vein from an arm, leg, or the internal mammary artery is used to build a detour (bypass) around the coronary artery blockage. Bypass surgery is appropriate for those patients with blockages in two or three major coronary arteries, those with severely narrowed left main coronary arteries, and those who have not responded to other treatments. It is performed in a hospital under general anesthesia. A heart-lung machine is used to support the patient while the healthy vein or artery is attached past the blockage to the coronary artery. About 70% of patients who have bypass surgery experience complete relief from angina; about 20% experience partial relief. Only about 3-4% of patients per year experience a return of symptoms. Survival rates after bypass surgery decrease over time. At five years after surgery, survival expectancy is 90%; at 10 years about 80%, at 15 years about 55%, and at 20 years about 40%.

Three newer surgical procedures for unblocking coronary arteries are currently being evaluated. Atherectomy is a procedure in which the cardiologist shaves off and removes strips of plaque from the blocked artery. In laser angioplasty, a catheter with a laser tip is inserted into the affected artery to burn or break down the plaque. A metal coil, called a stent, may be implanted permanently to keep a blocked artery open. Stenting is gaining popularity as an alternative to more invasive surgery.

Prognosis

In many cases, coronary artery disease can be successfully treated. Advances in medicine and healthier lifestyles have caused a substantial decline in death rates from coronary artery disease since the mid-1980s. New diagnostic techniques enable doctors to identify and treat coronary artery disease in its earliest stages. New technologies and surgical procedures have extended the lives of many patients who would otherwise have died. Research on coronary artery disease continues.

Health care team roles

Patients with coronary artery disease are most often treated by primary care physicians with consultation from cardiologists and cardiovascular surgeons when needed. Nurses, ECG technicians, laboratory technologists, and other allied health professionals have important roles in the diagnosis of coronary artery disease as well as in the institution of timely treatment. Nurses and other practitioners involved in triage or screening in the emergency department must accurately assess patients with chest pain or other indications of coronary artery disease.

ECG technicians, radiology technicians, and laboratory technologists are responsible for performing the diagnostic imaging studies, ECG and blood chemistries, to confirm the diagnosis of coronary artery disease. During the hospitalization, nurses, dieticians, respiratory and physical therapists collaborate to plan a cardiac rehabilitation program and provide patient and family education.

Patient education

Nurses, physical therapists and dieticians work together to educate patients and their families. Patients are taught to recognize and accurately describe symptoms such as pain, pressure, or heaviness in the chest, left arm, or jaw. Patients are advised to report any changes in the intensity or quality of their pain to nurses or other health care professionals while in the hospital. When necessary, they are counseled by nursing or pharmacy technicians about the use of sublingual (under the tongue) nitroglycerin to relieve chest pain. They are instructed to seek medical attention immediately should serious symptoms return after they have been discharged.

Along with instruction about medication, follow-up care, and the importance of participating in cardiac rehabilitation, patients are informed about ways to reduce their risk for myocardial infarction or other complications of coronary artery disease. This education is tailored to the individual patient's needs. It may include referral to a smoking cessation program; nutritional counseling to reduce dietary fat and sodium and achieve a desirable body weight; and recommendations to increase physical activity. Patient education also addresses treatment of any coexisting illnesses such as diabetes and instruction about ways to more effectively manage stress and anger.

Prevention

A healthy lifestyle can help prevent coronary artery disease and help keep it from progressing. A heart-healthy lifestyle includes eating right, regular exercise, maintaining a healthy weight, no smoking, moderate drinking, no recreational drugs, controlling hypertension, and managing stress. Cardiac rehabilitation programs are excellent to help prevent recurring coronary problems for patients at risk and those with a history of coronary events and procedures.

KEY TERMS

Angina— Chest pain that happens when diseased blood vessels restrict the flow of blood to the heart. Angina is often the first symptom of coronary artery disease.

Atherosclerosis— A process in which the walls of the coronary arteries thicken due to the accumulation of plaque in the blood vessels. Atherosclerosis is the cause of coronary artery disease.

Beta-blocker— A drug that blocks some of the effects of fight-or-flight hormone adrenaline (epinephrine and norepinephrine), slowing the heart rate and lowering the blood pressure.

Calcium-channel blocker— A drug that blocks the entry of calcium into the muscle cells of small blood vessels (arterioles) and keeps them from narrowing.

Coronary arteries— The main arteries that provide blood to the heart. The coronary arteries surround the heart like a crown, coming out of the aorta, arching down over the top of the heart, and dividing into two branches. These are the arteries in which coronary artery disease occurs.

HDL cholesterol— High-density lipoprotein cholesterol is a component of cholesterol that helps protect against heart disease. HDL is nicknamed "good" cholesterol.

LDL cholesterol— Low-density lipoprotein cholesterol is the primary cholesterol molecule. High levels of LDL increase the risk of coronary heart disease. LDL is nicknamed "bad" cholesterol.

Plaque— A deposit of fatty and other substances that accumulate in the lining of the artery wall.

Triglyceride— A fat that comes from food or is made from other energy sources in the body. Elevated triglyceride levels contribute to the development of atherosclerosis.

Resources

BOOKS

Ahya, Shubhada N., Kellie Flood, and Subramanian Paranjothi. The Washington Manual of Medical Therapeutics, 30th Edition. Philadelphia: Lippincott Williams & Wilkins, 2001, pp. 96-100.

American Heart Association and American Cancer Society. Living Well, Staying Well. New York: Time Books, 1996.

DeBakey, Michael E., and Antonio M. Gotto, Jr. "Coronary Artery Disease," and "Surgical Treatment of Coronary Artery Disease." In The New Living Heart. Holbrook, MA: Adams Media Corporation, 1997.

Notelovitz, Morris, and Diana Tonnessen. The Essential Heart Book for Women. New York: St. Martin's Press, 1996.

Texas Heart Institute. "Coronary Artery Disease, Angina, and Heart Attacks." In Texas Heart Institute Heart Owner's Handbook. New York: John Wiley & Sons, 1996.

ORGANIZATIONS

American Heart Association. National Center. 7272 Greenville Avenue, Dallas, TX 75231-4596. (214) 373-6300. 〈http://www.arhrt.org/〉.

National Heart, Lung, and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 496-4236. 〈http://www.nhlbi.nih.gov/nhlbi/nhlbi.htm〉.

Texas Heart Institute Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. (800) 292-2221. 〈http://www.tmc.edu/thi/his.html〉.

OTHER

"Atherectomy." American Heart Association. Accessed August 11, 2001. 〈http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/athere.html〉.

"NHLBI Report of the Workshop on Research in Coronary Heart Disease in Blacks." National Heart, Lung, and Blood Institute. Accessed August 11, 2005. 〈http://www.nhlbi.nih.gov/health/prof/heart/other/r_chdblk.htm〉.

Coronary artery disease

Definition

Coronary artery disease is a stenosis (narrowing) or blockage of the arteries and vessels that provide oxygenated blood to the heart. It is caused by atherosclerosis (hardening of the arteries), an accumulation of fatty plaque on the inner linings of arteries. The resulting blockage restricts blood flow through the coronary arteries. When blood flow is completely cut off, the result is myocardial infarction (heart attack).

Description

Coronary artery disease, also called coronary heart disease or atherosclerotic heart disease, is the leading cause of death for men and women in the United States. According to the American Heart Association, in 1998 one in every five deaths in the United States was caused by coronary artery disease. About every 29 seconds one American will have a heart attack; about every minute one American will die from a heart attack. Fourteen million Americans have active symptoms of coronary artery disease.

Many millions more have asymptomatic (silent) coronary disease, the first indication of which can be sudden death.

Coronary artery disease occurs when the coronary arteries become partially blocked or clogged, thereby depriving the heart muscle of oxygen (myocardial ischemia). When the blockage is temporary or partial, angina (chest pain or pressure) may occur. When the blockage completely and suddenly cuts off the flow of blood, the result is myocardial infarction.

Healthy coronary arteries are clean, smooth, and slick. The artery walls are flexible and can expand to let more blood through when the heart needs to work harder. Atherosclerosis is thought to begin with an injury to the linings of the inner walls of the arteries. This injury makes them susceptible to atherosclerosis and thrombosis (blood clots).

Causes and symptoms

Coronary artery disease is usually caused by atherosclerosis. Cholesterol and other fatty substances accumulate on the inner wall of the arteries.

This attracts fibrous tissue, blood components, and calcium, which harden into flow-obstructing plaques. If a blood clot suddenly forms on one of these plaques it can convert a partial obstruction to a total occlusion. This is known as coronary thrombosis. Congenital defects and spasms of a coronary artery may also block blood flow. There is evidence that infection from organisms such as chlamydia bacteria may be responsible for some cases of coronary artery disease.

A number of major contributing factors increase the risk of developing coronary artery disease. Some risk factors can be modified and others cannot. Persons with more of these risk factors are at greater risk of developing coronary artery disease.

Major risk factors

Major risk factors significantly increase the chance of developing coronary artery disease. Risk factors that cannot be changed include:

• Heredity. People whose parents have coronary artery disease, particularly those who develop it at younger ages, are more likely to be diagnosed with it. African Americans are also at increased risk because they experience a higher rate of severe hypertension than whites.
• Gender. Men under the age of 60 years of age are more likely to have myocardial infarctions than women of the same age. Over age 60, however, women have coronary artery disease at a rate equal to that of men.
• Age. Men over age 45 and women over age 55 years are more likely to have coronary artery disease. Occasionally, coronary disease affects individuals in the 30s. Older adults (those over 65) are more likely to die of a myocardial infarction. Older women are twice as likely as older men to die within a few weeks of a myocardial infarction.

Major risk factors that can be changed are:

• Smoking. Smoking greatly increases both the risk of developing coronary artery disease and resulting mortality. Smokers have two to four times the risk of non-smokers for sudden cardiac death and are more than twice as likely to have a myocardial infarction. They are also more likely to die within an hour of a heart attack. Second-hand smoke may also increase risk.
• High cholesterol. Cholesterol is produced by the body, and obtained from eating animal products such as meat, eggs, milk, and cheese. Age, gender, heredity, and diet affect cholesterol level. Risk of developing coronary artery disease increases as blood cholesterol levels increase. When combined with other factors, the risk is even greater. Total cholesterol of 240 mg/dL or more poses a high risk, and 200–239 mg/dL a borderline high risk. For LDL (low-density lipoprotein) cholesterol, high risk starts at 130–159 mg/dL, depending on other risk factors. Low levels of HDL (high-density lipoprotein) increases the risk of coronary disease; high HDL protects against it.
• Hypertension (high blood pressure). High blood pressure makes the heart work harder, and over time, weakens it. It increases the risk of myocardial infarction, stroke, kidney failure, and congestive heart failure. Blood pressure of 140 over 90 or above is considered high. When hypertension is combined with obesity, smoking, high cholesterol, or diabetes, the risk of myocardial infarction or stroke increases several times.
• Sedentary lifestyle and lack of physical activity. Inactivity increases the risk of coronary artery disease. Even modest physical activity is beneficial if done regularly.
• Diabetes mellitus. The risk of developing coronary artery disease is significantly increased for diabetics. More than 80% of diabetics die of some type of cardiovascular disease.

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but their precise contribution to the development of disease is not known yet.

Contributing risk factors are:

• Obesity. Excess weight increases the strain on the heart and increases the risk of developing coronary artery disease, even if no other risk factors are present. Obesity increases both blood pressure and blood cholesterol, and can lead to diabetes.
• Stress and anger. Stress and anger can produce physiological changes that contribute to the development of coronary artery disease, in part by increasing the risk of thrombosis. Stress, the mental and physical reaction to life's irritations and challenges, increases heart rate and blood pressure and can injure the lining of the arteries. Evidence shows that anger increases the risk of dying from heart disease. The risk of heart attack is more than double after an episode of anger.

Angina (chest pain) is the main symptom of coronary heart disease but it is not always present. Symptoms of angina typically include chest pain that may be described as heaviness, tightness, a burning sensation, squeezing, or pressure behind the breastbone. This pain may radiate to the left arm, neck, or jaw. Many people have no symptoms of coronary artery disease before having a heart attack; 63% of women and 48% of men who died suddenly of coronary artery disease had no previous symptoms of the disease, according to the American Heart Association.

Diagnosis

The diagnosis of coronary artery disease is made by the physician after a medical history, physical examination, and basic screening tests have been performed. The diagnostic work-up includes evaluation of body weight, blood pressure, blood lipid levels, and fasting blood glucose levels. Other diagnostic tests include resting and exercise electrocardiogram (ECG), echocardiography, radionuclide scans, and coronary angiography. A treadmill exercise (stress) test also may be used as a screening test for patients with significant risk factors but are asymptomatic.

An ECG may reveal if a patient has had a previous myocardial infarction (MI) or is having a MI. An ECG taken on a patient with coronary artery disease who is not having chest pain during the ECG and has not had a prior MI may be completely normal. An ECG technician places electrodes on the patient's chest, arms, and legs. These electrodes send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder that traces them on paper. The test takes about 10 minutes and is performed in a physician's office. A definite diagnosis cannot be made from electrocardiography. About 50% of patients with significant coronary artery disease have normal resting electrocardiograms. Another type of electrocardiogram, known as an exercise stress test, measures how the heart and blood vessels respond to exertion when the patient is exercising on a treadmill or a stationary bike. This test is performed in a physician's office or an exercise laboratory. It takes 15–30 minutes. Like many medical tests, it does not have 100% accuracy. It sometimes gives a normal reading when the patient has a heart problem or an abnormal reading when the patient does not.

If the electrocardiogram reveals a problem or is inconclusive, the next step is exercise echocardiography or nuclear myocardial scanning (radionuclide angiography). Echocardiography, cardiac ultrasound, uses sound waves to create an image of the heart's chambers and valves. A technician presses a hand-held transducer against the patient's chest to obtain an image that can be displayed on a monitor. It does not visualize the coronary arteries, but can detect abnormalities in heart wall motion caused by coronary disease. Performed in a cardiology outpatient diagnostic laboratory, the test takes about 30–60 minutes.

Nuclear myocardial scanning enables physicians to see if the myocardium (heart muscle) is being adequately perfused by the coronary arteries. Performed by radiologists and radiology technicians, nuclear scans involve injecting a small amount of radiopharmaceutical, such as thallium or sestamibi, into a vein. A camera that uses gamma rays to produce an image of the radioactive material records pictures of the heart. A radionuclide scan is comparable, in terms of radiation exposure, to a chest x ray. The tiny amount of radioactive material used disappears from the body in a few days. Radionuclide scans cost about four times as much as exercise stress tests but provide more information.

In nuclear myocardial scanning, a camera passes back and forth over the patient who lies on a table. Usually performed in a hospital's nuclear medicine department, the procedure takes 30–60 minutes.

Nuclear myocardial scanning is usually performed in conjunction with an exercise stress test. When the stress test is completed, thallium or sestamibi is injected. The patient resumes exercise for one minute to absorb the thallium. For patients who cannot exercise, cardiac blood flow and heart rate may be increased by intravenous dipyridamole (Persantine) or adenosine. Thallium or sestamibi scanning is done twice, immediately after injecting the radio-pharmaceutical and again four hours (and maybe 24 hours) later. Usually performed in a hospital's nuclear medicine department, each scan takes about 30–60 minutes.

Coronary angiography is the gold standard (most accurate method) for establishing the diagnosis of coronary artery disease, but it is also the most invasive. During coronary angiography the patient is awake but sedated. ECG electrodes are placed on the patient's chest and an intravenous line is inserted. A local anesthetic is injected into the site where the catheter will be inserted. The invasive cardiologist inserts a catheter into a groin artery and guides it into the aorta. A contrast dye is injected directly into the coronary arteries to determine whether they are obstructed. Coronary angiography is performed in a cardiac catheterization laboratory either in an outpatient or inpatient surgery unit. It takes from 30 minutes to two hours.

Treatment

Coronary artery disease can be treated many ways. The choice of treatment depends on the severity of the disease. Treatments include lifestyle changes and drug therapy, percutaneous transluminal coronary angioplasty, and coronary artery bypass surgery. Coronary artery disease is a chronic disease requiring lifelong care. Angioplasty or bypass surgery is not a “cure.”

Patients with less severe coronary artery disease may gain adequate control through lifestyle changes and drug therapy. Many of the lifestyle changes that prevent disease progression—a low-fat, low-cholesterol diet, weight loss if needed, exercise, and not smoking—also help prevent the disease from developing.

Drugs such as nitrates, beta-blockers, and calcium-channel blockers relieve chest pain and complications of coronary artery disease, but they cannot clear blocked arteries. Nitrates (nitroglycerin) improve blood flow to the heart. Beta-blockers (ace-butelol, propranolol) reduce the amount of oxygen required by the heart during stress. One type of calcium-channel blocker (verapamil, diltiazem hydrochloride) helps keep the arteries open and reduces blood pressure. Aspirin helps prevent blood clots from forming on plaques, reducing the likelihood of myocardial infarction. Cholesterol-lowering medications are also indicated in most cases.

Percutaneous transluminal coronary angioplasty and bypass surgery are invasive procedures to improve blood flow in the coronary arteries. Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty or PTCA, is a non-surgical procedure. A catheter tipped with a balloon is threaded through an artery in the groin into the blocked coronary artery. The balloon is inflated, compressing the plaque to enlarge the blood vessel and open the blocked artery. The balloon is deflated, and the catheter is removed. Coronary angioplasty is performed by an invasive cardiologist in a hospital and generally requires a stay of one or two days. Coronary angioplasty is successful about 90% of the time, but one-third of the time the artery restenoses (narrows again) within six months. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.

In coronary artery bypass surgery, a healthy vein from an arm, leg, or the internal mammary artery is used to build a detour (bypass) around the coronary artery blockage. Bypass surgery is appropriate for those patients with blockages in two or three major coronary arteries, those with severely narrowed left main coronary arteries, and those who have not responded to other treatments. It is performed in a hospital under general anesthesia. A heart-lung machine is used to support the patient while the healthy vein or artery is attached past the blockage to the coronary artery. About 70% of patients who have bypass surgery experience complete relief from angina; about 20% experience partial relief. Only about 34% of patients per year experience a return of symptoms. Survival rates after bypass surgery decrease over time. At five years after surgery, survival expectancy is 90%; at 10 years about 80%, at 15 years about 55%, and at 20 years about 40%.

Three newer surgical procedures for unblocking coronary arteries are currently being evaluated. Atherectomy is a procedure in which the cardiologist shaves off and removes strips of plaque from the blocked artery. In laser angioplasty, a catheter with a laser tip is inserted into the affected artery to burn or break down the plaque. A metal coil, called a stent, may be implanted permanently to keep a blocked artery open. Stenting is gaining popularity as an alternative to more invasive surgery.

Prognosis

In many cases, coronary artery disease can be successfully treated. Advances in medicine and healthier lifestyles have caused a substantial decline in death rates from coronary artery disease since the mid-1980s. New diagnostic techniques enable doctors to identify and treat coronary artery disease in its earliest stages. New technologies and surgical procedures have extended the lives of many patients who would otherwise have died. Research on coronary artery disease continues.

Caregiver concerns

Patients with coronary artery disease are most often treated by primary care physicians with consultation from cardiologists and cardiovascular surgeons when needed. Nurses, ECG technicians, laboratory technologists, and other allied health professionals have important roles in the diagnosis of coronary artery disease as well as in the institution of timely treatment. Nurses and other practitioners involved in triage or screening in the emergency department must accurately assess patients with chest pain or other indications of coronary artery disease.

ECG technicians, radiology technicians, and laboratory technologists are responsible for performing the diagnostic imaging studies, ECG and blood chemistries, to confirm the diagnosis of coronary artery disease. During the hospitalization, nurses, dieticians, respiratory and physical therapists collaborate to plan a cardiac rehabilitation program and provide patient and family education.

Patient education

Nurses, physical therapists and dieticians work together to educate patients and their families. Patients are taught to recognize and accurately describe symptoms such as pain, pressure, or heaviness in the chest, left arm, or jaw. Patients are advised to report any changes in the intensity or quality of their pain to nurses or other health care professionals while in the hospital. When necessary, they are counseled by nursing or pharmacy technicians about the use of sublingual (under the tongue) nitroglycerin to relieve chest pain. They are instructed to seek medical attention immediately should serious symptoms return after they have been discharged.

Along with instruction about medication, follow-up care, and the importance of participating in cardiac rehabilitation, patients are informed about ways to reduce their risk for myocardial infarction or other complications of coronary artery disease. This education is tailored to the individual patient's needs. It may include referral to a smoking cessation program; nutritional counseling to reduce dietary fat and sodium and achieve a desirable body weight; and recommendations to increase physical activity. Patient education also addresses treatment of any coexisting illnesses such as diabetes and instruction about ways to more effectively manage stress and anger.

Prevention

A healthy lifestyle can help prevent coronary artery disease and help keep it from progressing. A heart-healthy lifestyle includes eating right, regular exercise, maintaining a healthy weight, no smoking, moderate drinking, no recreational drugs, controlling hypertension, and managing stress. Cardiac rehabilitation programs are excellent to help prevent recurring coronary problems for patients at risk and those with a history of coronary events and procedures.

KEY TERMS

HDL cholesterol —High-density lipoprotein cholesterol is a component of cholesterol that helps protect against heart disease. HDL is nicknamed “good” cholesterol.

LDL cholesterol —Low-density lipoprotein cholesterol is the primary cholesterol molecule. High levels of LDL increase the risk of coronary heart disease. LDL is nicknamed “bad” cholesterol.

Plaque —A deposit of fatty and other substances that accumulate in the lining of the artery wall.

Triglyceride —A fat that comes from food or is made from other energy sources in the body. Elevated triglyceride levels contribute to the development of atherosclerosis.

Resources

BOOKS

Ahya, Shubhada N., Kellie Flood, and Subramanian Paranjothi. The Washington Manual of Medical Therapeutics, 30th Edition. Philadelphia: Lippincott Williams & Wilkins, 2001, pp. 96–100.

American Heart Association and American Cancer Society. Living Well, Staying Well. New York: Time Books, 1996.

DeBakey, Michael E., and Antonio M. Gotto, Jr. “Coronary Artery Disease,” and “Surgical Treatment of Coronary Artery Disease.” In The New Living Heart. Holbrook, MA: Adams Media Corporation, 1997.

Notelovitz, Morris, and Diana Tonnessen. The Essential Heart Book for Women. New York: St. Martin's Press, 1996.

Texas Heart Institute. “Coronary Artery Disease, Angina, and Heart Attacks.” In Texas Heart Institute Heart Owner's Handbook. New York: John Wiley & Sons, 1996.

ORGANIZATIONS

American Heart Association. National Center. 7272 Greenville Avenue, Dallas, TX 75231-4596. (214) 373-6300. http://www.arhrt.org/.

National Heart, Lung, and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 496-4236. http://www.nhlbi.nih.gov/nhlbi/nhlbi.htm.

Texas Heart Institute Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. (800) 292-2221. http://www.tmc.edu/thi/his.html.

OTHER

“Atherectomy.” American Heart Association. Accessed August 11, 2001. http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/athere.html.

“NHLBI Report of the Workshop on Research in Coronary Heart Disease in Blacks.” National Heart, Lung, and Blood Institute. Accessed August 11, 2005. http://www.nhlbi.nih.gov/health/prof/heart/other/r_chdblk.htm.

Barbara Wexler MPH

Coronary Heart Disease

Definition

Description

Demographics

Causes and symptoms

Diagnosis

Treatment

Nutrition/Dietetic concerns

Therapy

Prognosis

Prevention

Resources

Definition

Coronary heart disease is the narrowing or blockage of the arteries and vessels that provide oxygen and nutrients to the heart. It is caused by a condition called atherosclerosis, which is the gradual buildup of fatty materials on the arteries” inner linings. The blockage that results from the buildup restricts blood flow to the heart. When the blood flow is completely cut off, a heart attack can occur.

Description

Coronary heart disease also may be called coronary artery disease or simply heart disease. It is the leading cause of death in the United States among men and women.

When the heart works harder and needs more oxygen, the coronary arteries expand. But buildup of fatty materials, or plaque, from atherosclerosis causes the arteries to harden and narrow. If the arteries are unable to expand because of coronary artery disease, the heart is deprived of oxygen. The heart muscle can”t work properly without oxygen. The reduced blood flow and oxygen supply may cause angina, which is pain in the chest. It also may cause shortness of breath or other symptoms. Complete blockage or clotting at the site where the blood enters the heart can cause a heart attack.

Coronary heart disease can worsen over time. The heart muscles may weaken, even though no symptoms may be evident. Eventually, this leads to heart failure. In heart failure, the heart doesn’t suddenly stop, but fails to pump blood to the body the way that it should. Coronary heart disease also can lead to heart arrhythmias, or changes in the normal rhythm of heartbeat. These can be serious.

Demographics

According to the American Heart Association, coronary heart disease caused more than 250,000 deaths in 2004. But the number of deaths from the disease declined 33% from 1994 to 2004. Although about 325,000 people a year die of coronary attacks in hospital emergency departments without even being hospitalized, more than 15 million people in America live with a history of heart attack, angina pectoris, or both. More of these are males, but not by a wide margin. Black males have a higher death rate per 100,000 than white males, and men generally have a higher chance of dying from coronary heart disease than women.

Causes and symptoms

Coronary heart disease is caused by atherosclerosis. Some risk factors for coronary heart disease can’t be changed, such as inheriting a genetic risk for the disease.

Causes and risk factors

Age is a major risk factor for death from coronary heart disease. Over 83% of people who die from coronary heart disease are over age 65. Gender plays a role too, since men have a higher risk of heart attacks. Men tend to get heart disease earlier than women. While mean are at higher risk for coronary heart disease by about age 45, women are at risk for heart disease later in life, beginning at about age 55. People whose parents had heart disease also are at higher risk for coronary heart disease. Certain racial groups have higher risk as well, often because of a greater tendency toward obesity , high blood pressure, or diabetes.

Other risk factors can be affected by diet and lifestyle changes. Smoking is a big contributor to coronary heart disease. Not only do smokers have a risk two to four times that of nonsmokers of developing coronary heart disease, but they also have a higher risk of heart attack from the disease. In fact, a smoker with coronary heart disease is twice as likely as a non-smoker with coronary heart disease to die suddenly from the disease.

Cholesterol and saturated fat play a role in developing coronary heart disease. The body produces cholesterol and a person’s age, sex, and heredity can affect cholesterol levels. But diet also affects cholesterol. Both cholesterol and saturated fat tend to be found in the same foods. Dietary sources of both are meat, eggs, and other animal products. Risk of developing coronary heart disease rises steadily as levels of low-density lipoprotein (LDL) cholesterol rise or if a person has high cholesterol levels combined with high blood pressure and smoking.

Other diseases and conditions contribute to risk of coronary heart disease. High blood pressure makes the heart work harder and weakens it over time. Diabetes mellitus can be a serious risk for coronary heart disease and cardiovascular disease, which includes other disease to other arteries throughout the body. About three-fourths of people with diabetes die from heart disease or blood vessel disease.

KEY TERMS

Angina pectoris —Chest pain or discomfort. Angina pectoris is the more common and stable form of angina. Stable angina has a pattern and is more predictable in nature, usually occurring when the heart is working harder than normal.

Atherosclerosis — The hardening and narrowing of the arteries caused by the slow build-up of fatty deposits, or plaque, on the artery walls.

Triglyceride —A fat that comes from food or is made up of other energy sources in the body. Elevated triglyceride levels contribute to the development of atherosclerosis.

Weight and physical activity play a role in risk of coronary heart disease. Being overweight makes the heart work harder to do its everyday job of pumping blood to the body. Even when people have no other risk factors, obesity greatly increases risk of heart disease, particularly if weight is concentrated at the waist. Excess weight also raises blood pressure and affects cholesterol and triglyceride levels. Losing as little as 10 pounds can decrease risk for coronary heart disease, though maintaining a healthy weight is best. Being inactive contributes to weight gain and all of the associated conditions that then lead to coronary heart disease.

Stress also may play a role in coronary heart disease risk. However, the real problem is how people react to stress. For instance, overeating in response to stress leads to risk factors listed above. Drinking too much alcohol can cause some of the conditions listed above and lead to heart failure. However, studies have shown that moderate amounts of alcohol, described as about 1.5 fluid oz. of 80-proof spirits, 1 fluid oz. of 100-proof spirits, 4 fluid oz. of wine, or 12 fluid oz. of beer per day, may be good for the heart. The American Heart Association does not recommend that people who do not drink begin drinking or that anyone increase alcohol intake to meet these amounts, however.

Symptoms

The restricted blood flow to the heart caused by narrowing arteries may not produce any symptoms at first and many people are completely unaware that they have coronary heart disease. As the plaque builds up, symptoms begin to develop. One of the first signs may be chest pain that is triggered by physical or emotional stress. This pain often is referred to as angina. The pain feels much like pressure or tightening in the chest or it may be felt in the arm, neck, jaw, shoulder, or back. Sometimes the pain is confused with indigestion. Women may notice pain more often in the back or arm than in the chest and the pain may be brief and pass quickly.

Shortness of breath also is a symptom of coronary heart disease. This results from the heart’s decreasing ability to pump enough blood to the body to meet its needs. The person with shortness of breath also may feel very tired.

The most serious symptom of coronary heart disease is heart attack. Although some heart attacks start suddenly and are clearly occurring, most start slowly with uncertain symptoms. Discomfort in the center of the chest that lasts for several minutes that feels like squeezing, fullness, or pain is a sign that a heart attack is occurring or about to occur. The pain also may go away and come back. The pain may occur in one or both upper arms, the back, neck, jaw, or stomach. A person may experience shortness of breath with or without chest pain. Some people break out in a sweat or experience nausea or lightheadedness.

Diagnosis

A physician will ask questions about edical history, symptoms, and relatives with heart disease, as well as diet and lifestyle. A physical examination and routine blood tests also may be ordered as part of the evaluation. In addition, several examinations can be done to diagnose and evaluate coronary heart disease. These include:

• Resting electrocardiogram (ECG or EKG). This records electrical signals as they travel through the heart and usually is performed in a physician’s office. It is noninvasive and involves placing electrodes on the body.
• Holter monitoring. Also called ambulatory electrocardiography, this involves wearing a portable EKG unit for 24 hours to monitor inadequate blood flow to the heart as a person goes about everyday activities.
• Exercise stress test. This test takes an EKG reading while a person is walking on a treadmill or riding a stationary bicycle. It often is used to evaluate people who experience symptoms when exercising. A nuclear stress test may be used as well. In this examination, the patient exercises and the flow of blood to the heart while at rest and during exercise is measured by injecting minor amounts of a radioactive material into the bloodstream. A special camera can show which parts of the heart may receive less blood flow than normal.
• Angiogram. This is an x ray of the heart taken when a small tube, or catheter, is inserted into the arteries through a blood vessel in the groin or arm. The tip of the catheter can be guided to the coronary arteries and contrast is released. The contrast will be visible on x rays and will help show blood flow in the heart’s chambers. Today, angiograms can be performed through the use of contrast and imaging with computed tomography or magnetic resonance imaging.
• Computed tomography (CT) scan. A CT scan, which is a cross-sectional x ray of the body or an organ of the body, can show images of the arteries to determine atherosclerosis. Ultra-fast CT imaging also can detect calcium within plaque.
• Magnetic resonance imaging (MRI). This noninvasive method may be used to examine the tissues of the heart. MRI uses no radiation. Magnetic resonance angiography provides an alternative to the more invasive method that involves introducing a catheter into the body.
• Other imaging methods may be used to detect coronary heart disease, such as single photon emission computed tomography (SPECT).

Treatment

There are many ways to treat coronary heart disease, and the choice of treatment depends on the cause of the disease and its severity. Treatment ranges from lifestyle changes and use of medication to surgical procedures. People with less severe disease and fewer risk factors may be able to manage their disease through lifestyle changes and drug therapy. Changes in diet and an increase in exercise, as well as quitting smoking, can gain control of coronary heart disease. Often all treament procedures are used. Lifestyle factors such as diet and exercise are first line prevention and treatment methods. They are to be continued even after beginning medications and following surgery.

Medications used to treat coronary heart disease include:

• cholesterol-lowering medicines such as statins and fibrates
• blood thinners, or anticoagulants, to prevent blood clots from forming
• aspirin, also to help prevent clotting
• blood pressure medicines to lower blood pressure, such as angiotensin-converting enzyme (ACE) inhibitors
• calcium channel blockers, to relax blood vessels and lower blood pressure
• beta blockers to slow heart rate and lower blood pressure

Surgery or other procedures also may be recommended to treat coronary heart disease. A physician may be able to use a catheter to guide a tiny balloon into the artery. Once in place, the balloon is inflated and used to widen the artery by pushing the plaque up against the artery wall, Next, a stent, or mesh tube, is placed in the widened area to help keep the artery opened and clear for adequate blood flow.

Coronary artery bypass surgery reroutes, or bypasses, blood flow around the arteries that have clogged to improve blood flow to the heart. To perform the procedure, the surgeon takes a healthy blood vessel from another part of the body and uses it to create a detour around the clogged artery. This procedure requires open heart surgery and is reserved for people with multiple areas of artery blockage.

Heart attacks from coronary heart disease require emergency medical treatment.

Nutrition/Dietetic concerns

Nutrition is key to preventing and controlling coronary heart disease. The American Heart Association recommends that adults get no more than 300 mg of cholesterol a day in their diet and that those with heart disease get no more than 200 mg a day. It also is important to limit cholesterol that comes from animal-based foods and from saturated fats . All animal foods contain some cholesterol, so eating lean meats, fish, and poultry in smaller servings helps to control the amount eaten. Eating fat-free or low-fat dairy products also helps keep cholesterol and fats in check.

Controlling blood pressure helps prevent or manage coronary heart disease. A diet low in salts and high in fruits, vegetables, and whole grains helps to control blood pressure. The DASH diet is a balanced approach to controlling hypertension .

Eating lots of sugars and simple carbohydrates can lead to or complicate diabetes and affect triglyceride levels, increasing risk of coronary heart disease. It is important for people with diabetes to control their intake of white bread, bagels, cakes, soft drinks, and other carbohydrates. Studies show that whole-wheat breads, brown rice, and legumes are healthier choices to provide carbohydrates and protein in the diet. Even people with coronary heart disease who do not have diabetes should try to eat the recommended daily amounts of grains and fats and to get them from whole grains when possible.

In the past, there have been recommendations to follow high-protein, high-fat diets to control coronary heart disease. Studies have not shown these types of diets, such as the Atkins diet , to be successful at controlling weight long term or to reducing coronary heart disease. Research has shown that diets lower in carbohydrates and higher in vegetable sources of fat and protein moderately reduce the risk of coronary heart disease in women. Certain foods, such as fish and foods high in fiber (whole grains, fruits, and fresh vegetables) are healthy foods for the diets of people with coronary heart disease.

The most important aspect of nutrition and diet for people with coronary heart disease is to eat a balanced diet that helps them to lose and manage weight. The United States Department of Agriculture (USDA) and the United States Department of Health and Human Services revised the Dietary Guidelines for Americans in 2005. The guidelines are science-based and outline advice for choosing a nutritious diet and maintaining a healthy weight. The 2005 guidelines also address physical activity and food safety and make recommendations for special population groups. Finally, calorie requirements and servings are based more on gender, age, and level of physical activity, while in 2000, the servings were more uniform for all adults. The USDA also revised the traditional food pyramid to make it customized for individuals. These guidelines form the basis for healthy eating. The American Heart Association and the American Dietetic Association also offer heart healthy diet recommendations, as do family physicians and cardiologists.

Therapy

Some patients with coronary heart disease will be referred for cardiac rehabilitation, particularly following bypass surgery or if they have experienced angina or a heart attack. The rehabilitation may consist of an exercise plan to help regain stamina safely based on individual ability and needs, and education, counseling, and training. Training may include ways to better manage stress, as well as how to manage other lifestyle factors that contribute to coronary heart disease.

Prognosis

Coronary heart disease can be successfully managed and treated in many cases. Advances in diagnosis and techniques such as stenting have helped to improve the lives of people with the disease, bringing about a significant decline in death rates from coronary heart disease since the mid-1980s. However, as the leading cause of death in the United States, coronary heart disease is a serious condition that is best prevented and that requires careful management and attention once diagnosed. The more risk factors a person has, the worse the prognosis.

Prevention

Preventing coronary heart disease begins with knowing the risk factors and taking action to act on those factors. Managing all those contributing factors that can be avoided goes a long way in preventing the advancement of atherosclerosis and eventual coronary heart disease. By quitting smoking, moderating alcohol use, controlling blood pressure, preventing diabetes, and maintaining healthy cholesterol levels, people can prevent many of the causes of coronary heart disease. Maintaining a healthy body weight by eating a balanced diet with healthy-sized portions and participating in regular physical activity helps to prevent the disease. Those with known hereditary or other risk factors for coronary heart disease should have regular physical examinations with their physicians and should pay careful attention to the signs and symptoms of coronary heart disease and heart attack.

Resources

BOOKS

American Heart Association No-Fad Diet: A Personal Plan for Healthy Weight Loss. Clarkson Potter Publishers, 2005.

American Heart Association: To Your Health. A Guide to Heart-Smart Living. Clarkson Potter Publishers, 2001.

ORGANIZATIONS

American Dietetic Association. 120 South Riverside Plaza, Suite 2000. Chicago, IL 60605. (800) 877-1600. <http://www.eatright.org>

American Heart Association. 7272 Greenville Ave., Dallas, TX 75231. (800) 242-8721. <http://www.americanheart.org>

National Heart, Lung, and Blood Institute. P.O. Box 30105, Bethesda, MD 20284. (301) 592-8573. <http://www.nhlbi.nih.gov>

Teresa G. Odle

CORONARY ARTERY DISEASE

The heart, a powerful muscle that beats over 50,000 times in one day, is fed the blood and energy it needs through small tubes called coronary arteries (see Figure 1). Coronary artery disease (CAD) is the most common cause of death and disability in the United States and other industrialized countries, and it can be manifested if these arteries become narrowed by cholesterol to about half their normal diameter (see Figure 2). Cholesterol, a waxy substance, deposits slowly inside the artery. These deposits, which cause CAD, are called atherosclerotic plaques, having a central soft cholesterol core wrapped in hard fibrous tissue.

Figure 1

Plaque buildup stems from lifestyle and other coronary risk factors, including harmful diets, physical inactivity, smoking, stressful behavior patterns, elevated blood cholesterol, high blood pressure, and diabetes. The wide differences in CAD deaths among countries are largely lifestyle related. Racial differences in susceptibility tend to be minor. Diets overloaded with meat, eggs, butter, whole milk, cheese, and ice cream contain excessive cholesterol and saturated fat, which raise blood cholesterol, thus producing atherosclerosis.

Sedentary lifestyles in America are increasing. From 1991 to 1997, participation by high school students in physical education fell from 42 percent to 27 percent. Obesity increased by 60 percent in the United States in the 1990s because of decreasing physical activity and larger size and frequency of restaurant meals, especially inexpensive high-calorie fast foods. Obesity contributes to atherosclerosis in four ways. It raises blood pressure, cholesterol, and triglycerides (a type of blood fat), and it promotes diabetes, a strong and increasingly common CAD risk factor. A poor diet, and especially one containing excessive amounts of salty foods, can also increase blood pressure.

Smoking cigarettes promotes CAD by damaging the artery's inside lining and by lowering high-density lipoprotein (HDL) cholesterol, a protective fraction of the blood cholesterol. Fortunately, smoking rates have declined in the United States,

Figure 2

and ex-smokers who also exercise benefit by increasing HDL and lowering triglycerides.

In the United States in 1997, CAD caused over 1 million heart attacks and almost 500,000 deaths (one per minute), almost equally affecting men and women. Forty percent of deaths were sudden (within a few hours), usually from ventricular fibrillation, a very rapid beating of the ventricles, the heart's major muscle. A nonfatal heart attack damages the part of the ventricle deprived of blood (a myocardial infarction, or MI; see Figure3) with a 30 percent chance of recurrence within six years. Angina, less serious than an MI, is diagnosed by noting chest pain or "squeezing" after eating, exercise, emotional stress, or exposure to cold. About 350,000 new angina cases occur in the United States yearly; some of which progress to an MI, either nonfatal or fatal, especially if not treated.

The nearly 1 million new nonfatal MI or angina cases that occur yearly in the United States are treated aggressively, using relatively new surgical and nonsurgical technologies. The most common surgeries are coronary artery bypass graft surgery (CABGS) or angioplasty. About 1 million of these are performed yearly, at a cost of $3 billion. CABGS uses short lengths of veins (taken from the patient's legs) to bypass as many as five blocked or severely narrowed arteries. Angioplasty opens narrowed arteries by inflating a strong balloon, fracturing a plaque, and widening that artery segment. A metal tube (a stent) is often inserted to prevent that segment's closure. Nonsurgical approaches seek to change diet, exercise, smoking, body weight, and stress factors. Recently many new anticholesterol drugs, especially the statins, have reduced CAD extensively when used with lifestyle changes.

America's lost earnings and medical and disability payments from CAD cost about $130 billion yearly—an especially tragic burden since scientists now believe that most CAD events are preventable. Optimism regarding CAD's preventability stems from noting a 55 percent fall in CAD rates in the United States between its peak in 1967 and 1995. In turn, the peak represented a 50 percent rise from 1940.

The rise was caused by increases in smoking and rich diets associated with prosperity during and after World War II; the decline resulted from extensive health education that produced major decreases in smoking and dietary intake of saturated fat, and more recently by improved blood-pressure control from medications. CAD rates stopped declining in the United States in 1996, indicating an urgent need for more aggressive prevention. However, without the 55 percent decline since 1967, the human and financial burden would now be even greater.

The international picture has cause for great concern. Although CAD declined in developed countries from 1980 to 2000, the World Health Organization predicts that CAD will become the major cause of death in almost all countries by 2020, with over 10 million deaths per year predicted. Developing countries are repeating the earlier lifestyle mistakes of developed countries, ironically aided by aggressive promotion and export of cigarettes and unhealthy fast foods by the United States. Economists predict that rising CAD costs will greatly sap these countries' resources, delay economic growth, and cause unnecessary suffering.

Figure 3

Thus, the main lesson that the observed large fluctuations in CAD prevalence teaches is that social and environmental factors, not genetic, predominate in its cause. Therefore, CAD is an excellent example of how public health measures on lifestyle (and human behavior) can either benefit or harm our human potential.

John W. Farquhar

(see also: Atherosclerosis; Blood Lipids; Blood Pressure; Cardiovascular Diseases; Chronic Illness; Diabetes Mellitus; HDL Cholesterol; LDL Cholesterol; Lifestyle; Physical Activity; Smoking Behavior; Smoking Cessation; Tobacco Control )

Bibliography

American Heart Association (1998). 1999 Heart and Stroke Statistical Update. Dallas, TX: American Heart Association.

Farquhar, J. W., and Spiller, G. A. (2001). Diagnosis Heart Disease: Answers to Your Questions about Recovery and Lasting Health. New York: W. W. Norton.

Murray, C. J. L., and Lopez, A. D., eds. (1996). The Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability from Disease, Injuries, and Risk Factors in 1990 and Projected to 2020. Cambridge, MA: Harvard University Press.

Simon, H. B. (1994). Conquering Heart Disease: New Ways to Live Well without Drugs and Surgery. Boston: Little, Brown & Co.