context: Cholesterol plaques can be the cause of heart disease. Plaques begin in artery walls and grow over years. The growth of cholesterol plaques slowly blocks blood flow in the arteries. Worse, a cholesterol plaque can suddenly rupture. The sudden blood clot that forms over the rupture then causes a heart attack or stroke. Blocked arteries caused by plaque buildup and blood clots are the leading cause of death in the U. S. Reducing cholesterol and other risk factors can help prevent cholesterol plaques from forming. Occasionally, it can even reverse some plaque buildup. Cholesterol plaques form by a process called atherosclerosis. Another name for atherosclerosis is "hardening of the arteries." LDL or "bad cholesterol" is the raw material of cholesterol plaques. Progressive and painless, atherosclerosis grows cholesterol plaques silently and slowly. The eventual result is blocked arteries, which places blood flow at risk. The cholesterol plaques of atherosclerosis are the usual cause of heart attacks, strokes, and peripheral arterial disease. These conditions together are are major contributors to cardiovascular disease. Cardiovascular disease is the No. 1 killer in America, causing more than 900,000 deaths each year. Cholesterol plaques start developing in the walls of arteries. Long before they can be called plaques, hints of atherosclerosis can be found in the arteries. Even some adolescents have these "fatty streaks" of cholesterol in their artery walls. These streaks are early precursors of cholesterol plaques. They can't be easily detected by tests. But researchers have found them during autopsies of young victims of accidents and violence. Atherosclerosis develops over years. It happens through a complicated process of cholesterol plaque formation that involves: Damaged endothelium. The smooth, delicate lining of blood vessels is called the endothelium. High cholesterol, smoking, high blood pressure, or diabetes can damage the endothelium, creating a place for cholesterol to enter the artery's wall. Cholesterol invasion. " Bad" cholesterol ( LDL cholesterol) circulating in the blood crosses the damaged endothelium. LDL cholesterol starts to accumulate in the wall of the artery. Plaque formation. White blood cells stream in to digest the LDL cholesterol. Over years, the toxic mess of cholesterol and cells becomes a cholesterol plaque in the wall of the artery. Once established, cholesterol plaques can behave in different ways. They can stay within the artery wall. The cholesterol plaque may stop growing, or may grow into the wall, out of the path of blood. Plaques can grow in a slow, controlled way into the path of blood flow. Slow-growing cholesterol plaques may or may not ever cause any symptoms -- even with severely blocked arteries. Cholesterol plaques can suddenly rupture -- the worst case scenario. This will allow blood to clot inside an artery. In the heart, this causes a heart attack. In the brain, it causes a stroke. Cholesterol plaques from atherosclerosis cause the three main kinds of cardiovascular disease: Coronary artery disease -- Stable cholesterol plaques in the heart's arteries can cause no symptoms or can cause chest pain called angina. Sudden cholesterol plaque rupture and clotting causes blocked arteries. When that happens, heart muscle dies. This is a heart attack, also called myocardial infarction. Cerebrovascular disease -- Cholesterol plaque can rupture in one of the brain's arteries. This causes a stroke, leading to permanent brain damage. Blockages can also cause transient ischemic attacks, or TIAs. A TIA has symptoms like those of stroke. But they are temporary and there is no permanent brain damage. However, patients who experience a TIA are at a much higher risk of a subsequent stroke, so medical attention and care is essential. Peripheral arterial disease -- Blocked arteries in the legs can cause pain on walking and poor wound healing due to poor circulation. Severe disease may lead to amputations. Atherosclerosis and cholesterol plaques are progressive -- meaning they get worse with time. They are also preventable. Nine risk factors are to blame for up to 90% of all heart attacks including: smoking high cholesterol high blood pressure diabetes abdominal obesity ("spare tire") stress not eating many fruits and vegetables excessive consumption of alcohol -- more than one drink per day for women, or more than one or two drinks per day for men not getting regular physical activity You may notice almost all of these have something in common: you can do something about them. Experts agree that reducing your risk factors leads to a lower risk of heart disease. For people at moderate or higher risk from cholesterol plaques, taking a baby aspirin a day can be important. Aspirin helps prevent clots from forming. Ask your doctor before starting aspirin, as it can have side effects. Once a cholesterol plaque is there, it's generally there to stay. With effective treatment, though, plaque buildup may slow down or stop. Some evidence shows that, with aggressive treatment, cholesterol plaques can even shrink slightly. In one major study, cholesterol plaques shrank 10% in size after a 50% reduction in blood cholesterol levels. The best way to treat cholesterol plaques is to prevent them from forming or progressing. That can be done with lifestyle changes and, if needed, medication. Reducing the risk factors that lead to atherosclerosis will slow or stop the process. Ways to reduce the amount of cholesterol in your body involves taking cholesterol and blood pressure medication, eating a healthy diet, getting frequent exercise, and not smoking. These treatments won't unclog arteries. They do, though, lower the risk of heart attacks and strokes. Various drugs can lower cholesterol levels including: statins fibrates niacin bile acid sequestrants Of these, statins are the most frequently prescribed cholesterol-lowering drugs. Using invasive procedures, doctors can see and unclog arteries, or provide a path for blood to go around blocked arteries. Treatments include: Angiography, angioplasty, and stenting: Using a catheter inserted into an artery in the leg, doctors can enter diseased arteries. This procedure is called cardiac catheterization. Blocked arteries are visible on a live X-ray screen. A tiny balloon on the catheter can be inflated to compress cholesterol plaque in the blocked arteries. Placing small tubes called stents helps to keep open blocked arteries. The stent is usually made of metal and is permanent. It can also be made of a material that the body absorbs over time. Some stents have medicine that helps keep the artery from getting blocked again. Bypass surgery: Surgeons harvest a healthy blood vessel from the leg or chest. They use the healthy vessel to bypass blocked arteries. These procedures involve a risk of complications. They are usually saved for people with significant symptoms or limitations caused by the cholesterol plaques of atherosclerosis.