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1 Headline text
2 Other Names
5.1 Blood vessels
7.1 Lifestyle changes
8.1 Primary prevention
8.2 Secondary and tertiary prevention
9 Chances of Developing Atherosclerosis
9.1 Modifiable risk factors
9.2 Non-modifiable risk factors
10 Related Problems
10.1 Related disorders
11 Clinical Trials
13 Expected Outcome
Atherosclerosis is the accumulation of plaque inside blood vessels . It usually starts early in life and progresses slowly, but the rate of its progression varies considerably from person to person. Because plaque buildup can slow down or prevent blood flow almost anywhere in the body, atherosclerosis contributes to many diseases, most importantly heart attack and stroke.
Atherosclerosis contributes to more mortality—half or more of all deaths—and serious morbidity in the Western world than any other disorder. The risk factors for atherosclerosis have been well studied, and significant public health efforts are directed toward lowering the incidence and severity of atherosclerosis.
Arteriosclerosis is a general term for hardening of the arteries. Atherosclerosis is a specific form of arteriosclerosis, and the most important, but the two terms are often used interchangeably. Two other types of arteriosclerosis that are different from atherosclerosis are recognized: arteriosclerosis obliterans and medial calcific arteriosclerosis.
Hardening of the arteries
The American Heart Association recognizes six stages of atherosclerotic lesion:
Type I lesions are present even in children, and are composed of isolated foam cells in the arterial wall.
Type II lesions are also known as fatty streak lesions and feature more foam cells.
Type III lesions feature pools of fatty material located outside the cells, and can be present in young adults.
Type IV lesions are called atheromas and have a core of cell-free lipid (fat).
Type V lesions are known as fibroatheromas and are surrounded by fibrous tissue and may also contain calcifications, which make the arteries remarkably hard and inflexible. These are present in older adults.
Type VI lesions are called complicated and include surface defects, blood clotting activity, and may result in formation of blood clots that can break off and be brought to other parts of the body by the blood stream.
Early atherosclerosis has no symptoms. In some cases, the first sign of atherosclerosis is a catastrophic event caused by a plaque in the artery breaks off and travels, or causes complete blockage of the blood supply to a vital organ. Other times, early diagnosis of atherosclerosis can be made based on symptoms in the organ(s) supplied by the affected blood vessels. Different diseases may develop depending on which arteries are affected.
Coronary artery disease: Atherosclerosis affecting the coronary arteries (the arteries that supply the heart) is a significant cause of heart attacks, and in some—but not all— cases can show up as a particular kind of chest pain, angina pectoris.
Carotid artery disease: The carotid arteries supply blood to the brain and are also susceptible to plaque formation. Atherosclerosis can lead to blockage of the carotid arteries and cause a stroke, heralded by the sudden loss of specific abilities, such as the ability to speak. Sometimes the turbulence of the blood rushing past the plaques can cause a sound called a bruit, which can be heard when a stethoscope is put over the carotids.
Peripheral arterial disease occurs when plaque builds up in the major arteries that supply the legs, arms, and pelvis. Reduced blood flow can lead to numbness, pain, and sometimes dangerous infections.
The exact causes of atherosclerosis are the subject of much active research, but the consensus is that damage to the cells lining the arteries, the endothelial cells, is the key event that causes the disease to begin and to get worse.
The vessels most often affected by atherosclerosis are large arteries with fast, turbulent blood flow. Arteries bring oxygen-rich blood from the heart to the rest of the body. The wall of an artery is made up of several layers: the innermost endothelium, which is adjacent to the flowing blood; the middle layer called the media; and the outermost adventitia. Importantly, monocytes (a type of inflammatory cell that travels in the bloodstream) are able to stick to and cross the endothelial layer, after which they take up residence in the blood vessel wall as macrophages.
Plaque is a waxy aggregate of fatty substances, cholesterol, intact and dead cells, calcium precipitates, and proteins such as fibrin. In an atherosclerotic plaque, there are three components:
Cells, including smooth muscle cells as well as macrophages that got there by migrating from the bloodstream
Connective tissue components, including collagen
Lipid (fat) deposits, both inside and outside of cells
Macrophages cause plaques to grow bigger when they ingest lipids that are circulating in the bloodstream, and cell debris that is sitting nearby in the plaque. When macrophages soak up lipids, they become foam cells. Foam cells can distort the inner surface of the blood vessel. As plaques grow, they can become detached from the blood vessel wall and attract platelet, which begins the process of blood clot formation.
Illustration showing a normal artery with normal blood flow (A) and an artery containing plaque buildup (B). Source: NIHDiagnosis
There are a number of ways to determine whether a person has risk factors for atherosclerosis, and to determine if he or she has atherosclerotic plaques.
Blood tests check the levels of certain fats, cholesterol, sugar, and proteins in the blood. Abnormal levels may indicate an increased risk for atherosclerosis.
Electrocardiograms, or EKGs, are simple tests that detect and record the heart's electrical activity with electrodes placed at various places on the body. Certain electrical patterns that the EKG detects can suggest the presence of coronary artery disease (atherosclerosis in the heart), or show evidence of heart attacks in the past (or present).
Ankle/brachial index refers to blood pressures measured in the ankles and compared to pressures in the arm. If significant peripheral arterial disease is impeding flow to the legs, the pressure in the ankles is expected to be much lower than that in the arms.
Echocardiography uses sound waves to create a moving picture of the heart and provides information about the size, shape, and dynamics of the heart.
Computed tomography scanning is a series of x-rays that are then combined into a creates computer-generated images of the heart, brain, or other areas of the body. The test can often show hardening and narrowing of large arteries.
Angiography uses dye and special imaging equipment to visualize blood flow through the arteries. It can demonstrate plaque blocking arteries and how severe the plaque is.
Treatment options include no- or low-cost "lifestyle" changes, medication regimens, or surgical options to remove plaques or restore circulation to vulnerable organs.
Making lifestyle changes can often help prevent or treat atherosclerosis. For some people, these changes may be the only treatment needed. The following can help decrease risk of atherosclerosis:
Following a healthy eating plan to prevent or reduce high blood pressure and to maintain a normal weight
Quitting smoking and avoiding exposure to secondhand smoke
Doctors have a wide range of drug choices for helping patients lower blood pressure and cholesterol levels, which in turn helps prevent atherosclerosis. Drugs for blood pressure management include beta blockers, ACE inhibitors, calcium channel blockers, and angiotensin-receptor blockers. Drugs for lowering cholesterol include statins. Aspirin also reduces the risk of dying from a second heart attack by reducing the ability of platelets to form blood clots, which are part of the atherosclerotic lesion.
If an atherosclerotic lesion is blocking flow in one of the coronary arteries, the best option to treat it may be stenting, angioplasty, or bypass grafting. Vascular surgeons can also remove plaques surgically in a procedure called an endarterectomy, or destroy the plaque with high-intensity laser beams mounted on catheters (laser angioplasty).
Primary prevention refers to preventing atherosclerosis before it starts. Since the disease is thought to begin in childhood, ways to prevent it must begin then. According to guidelines released in 2003 by the American Heart Association, atherosclerosis prevention in childhood includes giving the child a healthy diet, keeping weight within healthy ranges and monitoring blood pressure, preventing her exposure to secondhand smoke, and promoting plenty of activity. For children at higher risk owing to underlying health problems or a strong family history, the guidelines are more detailed and involve close monitoring of the child's cholesterol and body mass index. These guidelines are based on the best evidence available. For ethical and logistical reasons, there is never likely to be a research study in which some children get these healthy interventions and others do not.
Secondary and tertiary prevention
Secondary prevention refers to early diagnosis of a disease, and tertiary prevention refers to reducing the harmful effects of a disease once it has been diagnosed. Sometimes both these concepts are called secondary prevention.
The strategies for secondary prevention of atherosclerosis are similar to those for primary prevention. They include watching one's cholesterol and triglycerides (lipids), getting exercise, monitoring blood pressure, and in many cases taking medications such as statins or aspirin. For more information, visit the American Heart Association's page on prevention.
Chances of Developing Atherosclerosis
Many risk factors have been identified, and they are usually classified as modifiable (something a person can change) or non-modifiable (something a person can't change):
Modifiable risk factors
Smoking increases the chances of developing and dying from atherosclerosis.
High blood cholesterol, specifically at levels > 240 mg/dL, is a risk factor that can be modified by diet and medications.
High triglycerides, at levels > 400 mg/dL, are another risk factor.
High blood pressure, of 140 over 90 or higher, makes the heart muscle work harder and also harms the arteries.
Physical inactivity and obesity are highly correlated and increase the risk of atherosclerosis, even in the absence of other risk factors.
Diabetes, if uncontrolled, greatly increases the risk of death from atherosclerosis. Most diabetics die from heart attacks caused by atherosclerosis.
Sleep apnea is a disorder in which breathing stops or gets very shallow during sleep. Untreated sleep apnea raises the risk of high blood pressure, which is a risk factor for atherosclerosis.
Stress: Common "triggers" for a heart attack are an emotionally upsetting event or unaccustomed exercise.
Alcohol: Heavy drinking can damage the heart muscle and worsen other risk factors for atherosclerosis.
Non-modifiable risk factors
Heredity, or what is inherited from one's parents, contributes to the risk of atherosclerosis.
Gender: Before age 60, men are at higher risk than women.
Age: Risk is higher for men older than 45 and for women older than 55.
If the only problem atherosclerosis caused was plaques in vessels, it might not be as serious a disease. But the plaques themselves, because they can block blood flow or cause blood clots, lead to further problems. These include stroke, heart attack, and peripheral vascular disease.
Many people with atherosclerosis also have obesity, metabolic syndrome, diabetes, high blood pressure, and/or hyperlipidemia (abnormal cholesterol or triglycerides). These conditions are thought to contribute to the development of atherosclerosis.
For a list of American government-sponsored clinical trials investigating atherosclerosis, click here. People interested in joining a trial may visit the National Institutes of Health's Patient Recruitment page.
Because atherosclerosis is so common and so deadly, and because it is thought to result from the complicated interaction of many factors, it is the topic of a great deal of research. Recent avenues of research include some of the following topics.
Omega-3 fatty acids: Omega-3 fatty acids, which are found abundantly in wild fatty fish as well as flaxseed oil, are effective in the prevention and, possibly, the treatment of atherosclerosis. Research is ongoing into who might benefit most from eating omega-3 fatty acid-rich foods.
Vitamin E and other antioxidants: There is conflicting evidence available as to the usefulness of taking vitamin E supplements to prevent or treat atherosclerosis.
Atherosclerosis is usually a lifelong condition, but in some cases it can be reversed.
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Categories: Atherosclerosis | Arteriosclerosis | Arterial Occlusive Diseases | Vascular Diseases | Cardiovascular Diseases | Diseases