Atherosclerosis is a disease that causes the walls of an artery to thicken, impairing blood flow. It can occur in any area of the body, but is most important when it happens in the heart, brain or blood vessels leading to the brain.
Blood flow is impaired because the channel through the artery has narrowed due to the formation of plaques (raised patches) in the inner lining of the arteries. These plaques are found most often in people with high concentrations of cholesterol in the bloodstream.
The number and thickness of plaques increase with age, causing loss of the smooth lining of the blood vessels and encouraging the formation of blood clots. Sometimes fragments of clots (thrombi) break off and form emboli, which travel through the bloodstream and block smaller vessels.
Atherosclerosis is responsible for more deaths in the U.S. than any other condition. Atherosclerotic heart disease, involving the coronary arteries (coronary heart disease), is the most common cause of death, accounting for one-third of all deaths. Atherosclerotic interference with blood supply to the brain (stroke) is the third most common cause of death after cancer.
Atherosclerosis also causes a great deal of serious illness by reducing the flow of blood in other major arteries, such as to the kidneys, legs, and intestines.
The exact cause of atherosclerosis isn’t known. However, studies show that atherosclerosis is a slow, complex disease that may start in childhood. It develops faster as you age.
Atherosclerosis may start when certain factors damage the inner layers of the arteries. These factors include:
- High amounts of certain fats and cholesterol in the blood
- High blood pressure
- High amounts of sugar in the blood due to insulin resistance or diabetes
When damage occurs, your body starts a healing process. Fatty tissues release compounds that promote this process. This healing causes plaque to build up where the arteries are damaged.
Over time, the plaque may crack. Blood cells called platelets clump together to form blood clots where the cracks are. This narrows the arteries more and worsens angina (chest pain) or causes a heart attack.
Symptoms of Atherosclerosis
Unfortunately, atherosclerosis produces no symptoms until the damage to the arteries is severe enough to restrict blood flow.
Restriction of blood flow to the heart muscle due to atherosclerosis can cause angina pectoris or a myocardial infarction (a heart attack).
Restriction of blood flow to the muscles of the legs causes intermittent claudication (pains in the legs brought about by walking and relieved by rest). Narrowing of the arteries supplying blood to the brain may cause transient ischemic attacks (symptoms and signs of a stroke lasting less than 24 hours) and episodes of dizziness, or ultimately, to a stroke itself.
Treatment of Atherosclerosis
Medication is unsatisfactory for treating atherosclerosis, since the damage has already been done. Anticoagulant drugs have been used to try to minimize secondary clotting and embolus formation.
Vasodilator drugs are helpful in providing symptom relief, but will not cure atherosclerosis.
Balloon angioplasty with stenting is often effective in opening narrowed vessels and improving blood supply.
Surgical treatment is available for those unresponsive to medical treatment or in certain high-risk situations. The blood supply to the heart can also be restored by coronary artery bypass surgery.