heart disease

Heart Disease CAD Go inside the body to see how heart disease develops.

A structural or functional abnormality of the heart, or of the blood vessels supplying the heart, that impairs its normal functioning.

Any abnormal condition of the heart (organic, mechanical, or functional) that causes difficulty.

Definition

Heart disease is the narrowing or blockage of the arteries and vessels that provide oxygen and nutrient-rich blood to the heart. It is caused by atherosclerosis, an accumulation of fatty materials on the inner linings of arteries that restricts blood flow. When the blood flow to the heart is completely cut off, the result is a heart attack because the heart is starved of oxygen.

Description

Heart disease, also called coronary heart disease or coronary artery 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 somewhat 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.

Heart disease occurs when the coronary arteries become partially blocked or clogged. This blockage limits the flow of blood through the coronary arteries, the major arteries supplying oxygen-rich blood to the heart. The coronary arteries expand when the heart is working harder and needs more oxygen. 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 blood flow, the result is heart attack (myocardial infarction or heart muscle death).

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

Causes & Symptoms

Heart 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. They then harden into artery-clogging plaques. Atherosclerotic plaques often form blood clots that can also block the coronary arteries (coronary thrombosis). Congenital defects and muscle spasms of arteries or heart muscles also block blood flow. Recent research indicates that infection from organisms such as chlamydia bacteria may be responsible for some cases of heart disease.

A number of major contributing risk factors increase the chance of developing heart disease. Some of these can be changed and some cannot. The greater the number of risk factors, the greater the chance of developing heart disease.

Major Risk Factors

Major risk factors significantly increase the chance of developing heart disease. These include:

• Heredity. People whose parents have heart disease are more likely to develop it. African-Americans are also at increased risk because they experience a high rate of severe hypertension.
• Gender. Men are more likely to have heart attacks than women and to have them at a younger age. Over the age of 60, however, women have heart 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 heart disease. Occasionally, heart disease may strike men or women in their 30s. People over 65 are more likely to die from a heart attack. Older women are twice as likely as older men to die within a few weeks of a heart attack.
• Smoking. Smoking increases both the chance of developing heart disease and the chance of dying from it. Smokers are more than twice as likely as nonsmokers to have a heart attack and are two to four times more likely die from it.
• High cholesterol levels. Dietary sources of cholesterol are meat, dairy food, eggs, and other animal fat products. It is also produced by the body. Age, body fat, diet, exercise, heredity, and sex 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 heart disease increases steadily as blood cholesterol levels increase above 160 mg/dL.
• 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. The risk of heart attack or stroke is raised several times for people with high blood pressure combined with obesity, smoking, high cholesterol levels, or diabetes.
• Lack of physical activity. Lack of exercise increases the risk of heart disease. Even modest physical activity, like walking, is beneficial if done regularly.
• Diabetes mellitus. The risk of developing heart 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 heart disease, but their significance is not known yet. Contributing risk factors are:

• Obesity. Excess weight increases the strain on the heart and increases the risk of developing heart disease even if no other risk factors are present. Obesity increases blood pressure and blood cholesterol and can lead to diabetes.
• Hormone replacement therapy (HRT). Even though physicians once believed that HRT could help prevent heart disease in women, the Women's Health Initiative (WHI) released information in 2002 and 2003 showing that use of combined hormones (estrogen and progestin) is harmful in women who already have coronary artery disease.
• Stress and anger. Some scientists believe that poorly managed stress and anger can contribute to the development of heart disease and increase the blood's tendency to form clots (thrombosis). Stress increases the heart rate and blood pressure and can injure the lining of the arteries.
• Chest pain (angina). Angina is the main symptom of coronary heart disease but it is not always present. Other symptoms include shortness of breath, chest heaviness, tightness, pain, a burning sensation, squeezing, or pressure either behind the breastbone or in the left arm, neck, or jaws. According to the American Heart Association, 63% of women and 48% of men who died suddenly of heart disease had no previous symptoms of the disease.

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 blood lipid levels, blood pressure, fasting blood glucose levels, weight, and other indicators. Other diagnostic tests include resting and exercise electrocardiograms, echocardiography, radionuclide scans, and coronary angiography. The treadmill exercise (stress) test is an appropriate screening test for those with high risk factors even though 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. 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. Both tests can be performed in a physician's office or outpatient facility.

Echocardiography, or cardiac ultrasound, uses sound waves to create an image of the heart's chambers and valves. A technician 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. The test does not reveal the coronary arteries themselves but can detect abnormalities in the heart wall caused by heart disease. Typically performed in a doctor's office or outpatient facility, 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 a radiopharmaceutical, such as thallium, into the bloodstream. As the patient lies on a table, a camera that uses gamma rays to produce an image of the radioactive material passes over the patient and records pictures of the heart. Radionuclide angiography is usually performed in a hospital's nuclear medicine department. The radiation exposure is about the same as that in a chest x ray.

Coronary angiography is considered the most accurate method for making a diagnosis of heart disease but it is also the most invasive. During coronary angiography the patient is awake but sedated. The cardiologist inserts a catheter into a blood vessel and guides it into the heart. A contrast dye (a radiopaque substance that is visible on x ray) is injected into the catheter and x rays are taken. Coronary angiography is performed in a cardiac catheterization laboratory in either an outpatient or inpatient surgery unit.

Treatment

Herbal medicine has a variety of remedies that may have a beneficial effect on heart disease. Garlic (Allium sativum), myrrh (Commiphora molmol), oats (Avena sativa) may help reduce cholesterol and hawthorn (Crataegus spp.), linden (Tilia europaea), and yarrow (Achillea millefolium) are sometimes recommended to control high blood pressure, a risk factor for heart disease. Tea, especially green tea (Camellia sinensis), is high in antioxidants; studies have shown that it may have a preventative effect against atherosclerosis. Coenzyme Q10 has been shown to be beneficial for 70% of patients with congenitive heart failure. According to Dr. Elson Haas, taurine, an amino acid found in meat and fish proteins, is used to treat heart arrhythmia. Two grams three times a day for people with congestive heart failure showed improved cardiovascular functions.

Yoga and other bodywork, massage, relaxation, aromatherapy, and music therapies may also help prevent heart disease and stop, or even reverse, the progression of atherosclerosis. Vitamin and mineral supplements that reduce, reverse, or protect against heart disease include B-complex vitamins, calcium, chromium, magnesium, L-carnitine, zinc, and the antioxidant vitamins C and E. The effectiveness of vitamins C and E is still under debate, and physicians caution that they be used in moderation.

Traditional Chinese medicine (TCM) may recommend herbal remedies, massage, acupuncture, and dietary modification. A healthy diet (including cold water fish as a source of essential fatty acids) and exercise are important components of both alternative and conventional prevention and treatment strategies.

New reports on diet and heart disease have answered some questions, but others remain unclear. While one study concludes that four servings per day of fruit and vegetables are associated with a slight drop in risk of heart disease, eight or more servings per day can produce a significant drop in risk. Another study showed that consuming legumes at least four times per week lowered risk of heart disease from 11% to 22% compared with consuming legumes less than once a week. Research on antioxidants continues to send mixed messages, with some reports showing that vitamins E, C, and other antioxidants can help prevent heart disease, and other studies showing they have no effect. Many physicians and researchers therefore recommend that those wanting to follow healthy heart habits continue to eat a diet rich in antioxidants but recognize that there is probably no value in adding antioxidant supplements to a good diet.

Allopathic Treatment

Heart disease can be treated in many ways. The choice of treatment depends on the patient and the severity of the disease. Treatments include lifestyle changes and drug therapy, coronary artery bypass surgery, and percutaneous transluminal coronary angioplasty, although these are not cures. Heart disease is a chronic disease requiring lifelong care.

Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty, is a nonsurgical 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 then deflated and the catheter removed.

People with moderate heart disease may gain adequate control through lifestyle changes and drug therapy. Drugs such as nitrates, beta-blockers, and calcium-channel blockers relieve chest pain and complications of heart disease, but they cannot clear blocked arteries. Nitrates improve blood flow to the heart, and beta-blockers reduce the amount of oxygen required by the heart during stress. Calcium-channel blockers help keep the arteries open and reduce blood pressure.

Aspirin helps prevent blood clots from forming on plaque deposits, reducing the likelihood of a heart attack and stroke. Cholesterol-lowering medications are also indicated in most cases.

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 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. 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.

Three other surgical procedures for unblocking coronary arteries are being studied and used on a limited basis. 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 can be implanted permanently to keep a blocked artery open. Stenting is becoming more common.

Expected Results

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

Prevention

A healthy lifestyle can help prevent heart disease and slow its progress. A heart-healthy lifestyle includes maintaining a healthy diet, regular exercise, weight maintenance, no smoking, moderate drinking, 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 and limited salt. Saturated fats should equal seven to 10% of calories, polyunsaturated fats should equal about 10%, monounsaturated fat should be 15%, and carbohydrates should total 55-60% of daily calories. Fat should comprise no more than 30% of total daily calories and should be taken preferably as fish oil, olive oil, seeds, and vegetable oil. New evidence shows that replacing saturated fat with unsaturated fat is more effective in lowering coronary heart disease risk than reducing total fat intake. Eating cold-water fish or taking comparable omega-3 polyunsaturated fatty acid supplements can help prevent cardiac death. In 2003, the American Heart Association began advocating daily servings of fatty fish or three fish oil capsules daily.

Cholesterol, a waxy substance containing fats, is found in foods such as meat, dairy, eggs, and other animal products. It is also 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, lowcholesterol diet.

Antioxidants are chemical compounds in plant foods. When people eat antioxidant-rich foods, they may improve the function of the arteries, prevent arterial plaque formation, and reduce their risk of cancer. Colorful vegetables and fruits are sources of antioxidants, and are rich in fiber, vitamins, and minerals. They are lowcalorie 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. Whole grains, especially whole oats and oat bran, reduce cholesterol.

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.

Exercising Regularly

Aerobic exercise can lower blood pressure, help control weight, and increase HDL (good) cholesterol. It also 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. People with heart disease or risk factors should consult a doctor before beginning an exercise program.

Maintaining a Desirable Body Weight

People who are 20% or more over their ideal body weight have an increased risk of developing heart disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost HDL cholesterol. It may also reduce blood pressure. Eating right and exercising are two key components of losing weight.

Quitting Smoking

Smoking has many adverse effects on the heart. It increases the heart rate, constricts major arteries, and can create irregular heartbeats. It also 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. When smokers quit the habit, heart damage can be repaired. Several studies have shown that ex-smokers face the same risk of heart disease as nonsmokers within five to 10 years after they quit.

Drinking in Moderation

Modest consumption of alcohol may actually protect against heart 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. Excessive drinking is always bad for the heart. It usually raises blood pressure and can poison the heart and cause abnormal heart rhythms or even heart failure.

Seeking Diagnosis and Treatment for Hypertension

High blood pressure, one of the most common and serious risk factors for heart disease, can be completely controlled through lifestyle changes and medication. Seeking out the diagnosis and treatment is critical because hypertension often exhibits no symptoms; many people do not know they have it. 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.

Managing Stress

Everyone experiences stress. Stress can sometimes be avoided and, when it is inevitable, it can be managed through relaxation techniques, exercise, and other methods.

Resources

Books

American Heart Association. 2000 Heart and Stroke Statistical Update. Dallas, TX.: American Heart Association, 1999.

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

Haas, Elson, M.D. Staying Healthy with Nutrition: The Complete Guide to Diet and Natural Medicine. Berkeley, CA: Celestial Arts, 1992.

Ody, Penelope. The Complete Medicinal Herbal. New York: DK Publishing. 1993.

Periodicals

Cerrato, Paul L. "Antioxidants, CAD, and Diabetes." Contemporary OB/GYN (January 2002): 111.

Dioreto, Stacy. "Legume Intake Lowers CHD Risk." Patient Care (January 30, 2002): 41.

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

Mirzaei, H.A. "Role of Soy Protein in Lowering LDL Levels." The Journal of Nutrition (March 2002): 604S.

Sadovsky, Richard. "Omega-3 Fatty Acids and CHC Prevention." American Family Prevention (March 1, 2002): 952.

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. National Center. 7272 Greenville Avenue, Dallas, Texas 75231. 1-800-AHA-USA1. .

Other

Lycos Health with Web MD. "Antioxidants." http://webmd.lycos.com/content/dmk/dmk_article_6463016.

Masley, Dr. Steven, M.D. The Vitality Center. http://www.drmasley.com/index.htm.

[Article by: Paula Ford-Martin; Teresa G. Odle]

For more information on heart disease, visit Britannica.com.

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