What is atherosclerosis?
Atherosclerosis is the medical name for hardening and narrowing of the arteries where the body's vital pipework gets clogged up with fatty deposits called plaques or atheroma.
Atherosclerosis develops over time, but the restriction it causes to blood flow can damage organs and increases the risk of blood clots, heart attacks and strokes.
Most adults are likely to have some degree of atherosclerosis, especially over the age of 40. Atherosclerosis is also more common in men than it is in women.
How atherosclerosis happens
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.
Atherosclerosis starts when high blood pressure, smoking, or high cholesterol damage the endothelium. At that point, cholesterol plaque – called atheroma - begins to form.
Cholesterol invasion. Bad cholesterol, or LDL, crosses damaged endothelium. The cholesterol enters the wall of the artery.
Plaque formation. Your white blood cells stream in to digest the LDL cholesterol. Over years, the accumulating mass of cholesterol and cells becomes a plaque in the wall of the artery.
Atherosclerosis tends to happen throughout the body.
Atherosclerosis usually causes no symptoms until middle or older age. Once narrowing becomes severe, it restricts blood flow and can cause pain. Blockages can also suddenly rupture, causing blood to clot inside an artery.
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. Because they don't block blood flow, these plaques may never cause any symptoms.
- They can grow in a slow, controlled way into the path of blood flow. Eventually, they cause significant restriction in blood flow. Pain on exertion (in the chest or legs) is the usual symptom.
- The worst-case scenario: plaques can suddenly rupture, allowing blood to clot inside an artery, completely obstructing blood flow. 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 obstructs blood flow to the heart causing heart muscle to die. This is a heart attack, or myocardial infarction.
- Cerebrovascular disease: Ruptured plaques in the brain's arteries can obstruct blood supply to the brain causing a stroke, with the potential of permanent brain damage. Temporary blockages in an artery can cause transient ischaemic 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. Peripheral artery disease causes poor circulation. This causes pain on walking and poor wound healing. Severe disease may lead to the need for amputations.