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What Is Atherosclerosis?

Atherosclerosis -- hardening and narrowing of the arteries -- gets a lot of bad press but with good reason. This progressive process silently and slowly blocks arteries, putting blood flow at risk.

Atherosclerosis is the usual cause of heart attacks, strokes, and peripheral vascular disease -- what together are called "cardiovascular disease." Cardiovascular disease is the No. 1 killer in America, with more than 800,000 deaths in 2005.

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Under the Affordable Care Act, many health insurance plans will cover preventive care services, including blood pressure and cholesterol screenings, at no cost to you. Learn more. 

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How does atherosclerosis develop? Who gets it, and why? This deadly process is preventable and treatable. Read on, and get to know your enemy.

What Causes Atherosclerosis?

First, an Anatomy 101 review: Arteries are blood vessels that carry blood from the heart throughout the body. They're lined by a thin layer of cells called the endothelium. The endothelium works to keep the inside of arteries toned and smooth, which keeps blood flowing.

According to experts, atherosclerosis begins with damage to the endothelium caused by high blood pressure, smoking, or high cholesterol. That damage leads to the formation of plaque.

When bad cholesterol, or LDL, crosses the damaged endothelium, the cholesterol enters the wall of the artery. That causes your white blood cells to stream in to digest the LDL. Over years, the accumulating mess of cholesterol and cells becomes a plaque in the wall of the artery.

Plaque is a jumble of cholesterol, cells, and debris that creates a bump on the artery wall. As atherosclerosis progresses, that bump gets bigger. And when it gets big enough, it can create a blockage. That process goes on throughout your entire body. As a result, not only is your heart at risk but you are also at risk for stroke and other kinds of health problems.

Atherosclerosis usually causes no symptoms until middle or older age. But as narrowings become severe, they choke off blood flow and can cause pain. Blockages can also suddenly rupture, causing blood to clot inside an artery at the site of the rupture.

Atherosclerosis and Plaque Attacks

Plaques from atherosclerosis can behave in different ways.

  • They can stay within the artery wall. There, the plaque grows to a certain size and stops. Since this plaque doesn't block blood flow, it may never cause symptoms.
  • Plaque can grow in a slow, controlled way into the path of blood flow. Eventually, it causes significant blockages. Pain on exertion (in the chest or legs) is the usual symptom.
  • The worst-case scenario consists of plaques that suddenly rupture, allowing blood to clot inside an artery. In the brain, this causes a stroke; in the heart, a heart attack.

The plaques of atherosclerosis cause the three main kinds of cardiovascular disease:

  • Coronary artery disease: Stable plaques in the heart's arteries cause angina (chest pain on exertion). Sudden plaque rupture and clotting causes heart muscle to die. This is a heart attack, or myocardial infarction.
  • Cerebrovascular disease: Ruptured plaques in the brain's arteries causes strokes with the potential for permanent brain damage. Temporary blockages in an artery can also cause transient ischemic attacks (TIAs), which are warning signs of stroke; however, there is no brain injury.
  • Peripheral artery disease: Narrowing in the arteries of the legs caused by plaque causes poor circulation. This causes pain on walking and poor wound healing. Severe disease may lead to amputations.

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