ATHEROSCLEROSIS

DEFINITION

Atherosclerosis (pronounced ath-uh-ro-skluh-RO-siss) is the build-up of a waxy deposit on the inside of blood vessels. Atherosclerosis is a form of arteriosclerosis (pronounced ar-tir-ee-o-skluh-RO-siss). Arteriosclerosis refers to any condition in which the arteries become hard and less flexible. The two terms are often used interchangeably, although it is not really correct to do so.

DESCRIPTION

The arteries are blood vessels that carry blood from the heart to all parts of the body. Arteries are made up of several layers of tissue that are normally soft and pliable. The layers must be able to expand and contract as blood passes through them.

Arteries often become leathery and rigid. When that happens, blood may flow less easily through the arteries. The hardening of arteries is called arteriosclerosis. Many factors can cause arteriosclerosis. Normal aging, high blood pressure, and certain diseases, such as diabetes (see diabetes mellitus entry), are common causes of arteriosclerosis.

Atherosclerosis is a special form of arteriosclerosis. In atherosclerosis, only the inner lining of the artery is affected. Fatty materials deposit on the lining of the artery, forming a larger and larger mass. The mass is usually called a plaque (pronounced PLAK). It becomes more and more difficult for blood to flow through the artery. Eventually the artery may close completely.

The formation of a plaque in an artery can lead to a number of cardiovascular (heart and blood vessel) problems. If the plaque forms in an artery that leads to the heart, it may block the flow of blood to the heart, and a heart attack may occur. If the plaque occurs in an artery that leads from the heart, it may prevent the brain from getting the blood and oxygen it needs. The result is a stroke (see stroke entry).

The plaque may also break off from the artery wall and travel through the bloodstream. It may then block an artery somewhere else in the body, a process known as thrombosis. A thrombosis that blocks an artery in the heart produces a condition known as a coronary thrombosis.

Atherosclerosis can occur anywhere in the body. It can affect arteries of the neck, kidneys, thighs, and arms. In such cases, the interruption of blood flow can produce many medical conditions, such as kidney failure and gangrene (death of tissue).

CAUSES

The exact cause of atherosclerosis is not known. Some researchers consider it to be a natural consequence of aging. But that theory does not explain the actual process of the disease. What is known is that people with certain risk factors are much more likely to develop atherosclerosis than people without those risk factors. Some risk factors are beyond a person's control. For example, some people seem to be genetically more inclined to develop atherosclerosis than other people. Also, the disorder is more common among older than younger people. A person is not able to do much about his or her heredity or the aging process.

Some risk factors, however, are under a person's control. These factors include:

• Cigarette/tobacco smoking. Smoking increases the risk of developing atherosclerosis. It also increases the risk of dying from heart disease. Secondhand smoke may also increase risk.
• High blood cholesterol. Cholesterol is a soft, waxy substance produced naturally by the body. It also occurs in many foods, such as meat, eggs, and other animal products. A certain amount of cholesterol is needed to keep the body healthy. But high levels of cholesterol can increase the risk of atherosclerosis.
• High triglycerides. Triglycerides (pronounced tri-GLIS-uh-ride) are a form of fat. High levels of trigylcerides have been linked with various kinds of artery disease.
• High blood pressure. Blood pressure higher than normal (normal is measured 140 over 90) can make the heart work hard. Both the heart and arteries may become weak (see hypertension entry).
• Physical inactivity. Lack of exercise increases the risk of atherosclerosis.
• Obesity. Excess weight strains the heart. Both heart and arteries may be damaged (see obesity entry). Some risk factors for atherosclerosis that cannot be changed include:
• Heredity. People whose family members have had atherosclerosis are at risk for the disorder.
• Gender. Before age sixty men are more likely to have atherosclerosis than women. After sixty, the risk is equal for men and women.
• Age. The risk for atherosclerosis increases with age.
• Diabetes mellitus. Many diabetics die from heart attacks caused by atherosclerosis.

SYMPTOMS

The symptoms of atherosclerosis vary somewhat depending on the location of a plaque. If the plaque occurs in the arteries of the heart, the patient may experience chest pain, heart attack, or sudden death. A plaque in the brain may lead to sudden dizziness, weakness, loss of speech, or blindness. In arteries of the leg, plaques can lead to cramping and fatigue in the legs when walking. A plaque in the kidneys can cause high blood pressure that is difficult to treat.

DIAGNOSIS

A doctor may be led to suspect atherosclerosis based on any of the symptoms discussed. A variety of tests is available to confirm the diagnosis. For example, an electrocardiogram (pronounced ih-LEK-tro-KAR-dee-o-gram) measures electrical activity of the heart. An abnormal flow of blood to the heart can change this activity. Electrocardiograms are sometimes performed while a patient is taking part in vigorous activity, such as riding a stationary bicycle. Such tests are known as stress tests.

A coronary artery with atherosclerosis, buildup of waxy deposits inside the blood vessels. (Photograph by

Martin M. Rotker

. Reproduced by permission of

Phototake NYC

.)

An echocardiogram (pronounced ekko-KAR-dee-o-gram) uses sound waves to study the heart. The sound waves produce a pattern (an echo) as they pass through the heart. The echoes provide information about the heart's structure. Blockages in arteries can sometimes be detected by this method.

Radioactive isotopes can also be used to produce pictures of the heart. A radioactive isotope is a material that gives off some form of radiation. The radioactive isotope is first injected into the patient's bloodstream. It travels through the patient's body, giving off radiation. The radiation can be used to form a picture on a screen, somewhat like an X-ray photograph.

Coronary angiography (pronounced an-gee-AH-graffie) is the most accurate way to diagnose atherosclerosis. In this procedure, a catheter is inserted into a blood vessel in the patient's arm. A catheter is a long, narrow tube that can be pushed through the vein into the patient's heart. A dye is pumped through the catheter into the heart. Then, X-ray pictures are taken of the heart. The dye makes it possible to see structures of the heart in great detail. The presence of plaques can easily be seen.

TREATMENT

Mild cases of atherosclerosis can often be treated with changes in lifestyle. Patients can reduce the amount of fats and cholesterol in their diet, quit smoking, lose weight, and become more physically active. For more serious forms of atherosclerosis, other treatments may be necessary. These include the use of drugs and various forms of surgery.

A class of drugs that is used with atherosclerosis are designed to lower cholesterol. If the amount of cholesterol in the blood is reduced, the chance that plaques will form is also reduced. Aspirin may also be recommended because it tends to cause blood to become thinner.

One form of surgery used with atherosclerosis is angioplasty (pronounced AN-jee-o-PLAS-tee). In angioplasty a catheter tipped with a balloon is inserted into a blood vessel in the patient's thigh or arm. The catheter is then pushed upwards into the artery where a plaque exists. At that point, the balloon is inflated. The balloon pushes on the plaque. It may squeeze the plaque enough to open the artery to its normal size. Blood is then able to again flow through the artery.

Bypass surgery may also be used to treat atherosclerosis. In bypass surgery, the portion of an artery that is blocked by plaque is clamped off. A blood vessel is taken from some other part of the patient's body and inserted just before and just after the section of artery that has been blocked off. Blood is given a new pathway to flow through the body, bypassing the damaged artery. Bypass surgery is completely successful in about 70 percent of all cases and partially successful in another 20 percent.

Alternative Treatment

One focus of alternative treatments for atherosclerosis is diet. Practitioners recommend many of the changes suggested by traditional medicine including reducing the amount of cholesterol and fats eaten. Alternative practitioners also suggest that patients eat more raw and cooked

Flowchart illustrating the progression of atherosclerosis. (Illustration by

Hans & Cassady

)

fish and fresh fruits and vegetables. Onion and garlic are particularly recommended.

A variety of herbs is also recommended to improve the patient's overall health. These herbs include hawthorn, ginger, hot red or chili peppers, yarrow, and alfalfa. Another focus of alternative treatments is helping patients to become more relaxed. In this way, they may feel less stress and experience a reduced blood pressure. Yoga, meditation, and massage are methods for improving relaxation.

PROGNOSIS

Atherosclerosis cannot be cured, but it can be delayed, stopped, and even reversed. One of the most critical steps that a patient can take is to control cholesterol levels. Doctors are now able to detect atherosclerosis in its early stages. That development allows earlier treatment to prevent the most serious complications of the disorder.

PREVENTION

The key to reducing the risk for atherosclerosis is to reduce the risk factors an individual has control over, which includes:

• Eating a healthy diet low in cholesterol and triglycerides. The diet should be high in fruits and vegetables.
• Exercising regularly. Physical activity can lower blood pressure and help control weight.
• Maintaining a desirable body weight.
• Stopping—or never starting—to use tobacco. Even people who smoke can reduce their risk of atherosclerosis by giving up the habit.
• Seeking treatment for hypertension. Hypertension is another name for high blood pressure. High blood pressure is probably a hereditary condition, but it can be brought under control by certain changes in lifestyle. These changes include reducing the amount of sodium and fat in the diet, exercising, learning how to manage stress, giving up smoking, and drinking alcohol in moderation.

FOR MORE INFORMATION

Books

American Heart Association. Guide to Heart Attack Treatment, Recovery, and Prevention. New York: Time Books, 1996.

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

Arnold, Caroline. Heart Disease. New York: Franklin Watts, 1990.

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

Parker, Steve. Heart Disease. New York: Franklin Watts, 1989.

Periodicals

"Landmark Study Shows Heart Disease Prevention Must Start Early." The Nation's Health (March 1997): p. 13.

Morgan, Peggy. "What Your Heart Wishes You Knew about Cholesterol." Prevention (September 1997): p. 96.

Organizations

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

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