Atherosclerosis and strokes

Atherosclerosis and strokes

Atherosclerosis is narrowing of the arteries, and is a leading cause of strokes.

Atherosclerosis progresses silently, without symptoms.

Reducing the risk factors of atherosclerosis with lifestyle changes can lower the risk of stroke.

There are two main types of strokes:

Ischaemic: An artery inside or leading to the brain becomes completely blocked. Usually this is caused by a blood clot that forms on an area of atherosclerosis. It can also be due to a blood clot travelling to the brain from the heart.

Most strokes (about 80%) are ischaemic, and most of those are caused by atherosclerosis.

Haemorrhagic: These strokes are caused by bleeding into the brain. Most commonly, high blood pressure causes a small artery to burst open. Abnormal blood vessels (such as aneurysms and arteriovenous malformations) are particularly likely to rupture. The bleeding disrupts healthy blood flow to brain tissue.

Haemorrhagic strokes are less common, making up about 20% of all strokes.

Regardless of whether a stroke is caused by atherosclerosis or bleeding, the symptoms are the same:

• Sudden weakness on one side in the face, arm or leg
• Problems speaking: slurred speech, or inability to remember words
• Sudden blurry or double vision.

Within hours of a stroke’s onset, brain tissue dies from lack of oxygen and nutrients, leaving permanent damage.

If stroke-like symptoms strike, the time to call 999 for help is now. Only prompt medical attention can help prevent permanent damage from a stroke.

With these sobering facts in mind, it’s worthwhile to understand the process by which atherosclerosis causes strokes.

Atherosclerosis: A major cause of strokes

Atherosclerosis occurs in the arteries of the brain in the same way it does elsewhere in the body:

• The inner layer of arteries (the endothelium) is damaged by high cholesterol,smoking or high blood pressure.
• Damaged endothelium allows LDL (“bad”) cholesterol to enter the artery wall, where it accumulates.
• The body sends a “clean-up crew” of white blood cells and other cells to the artery, to digest the LDL.
• Over years, ongoing cholesterol build-up - and the response to it - creates a bump on the artery wall called a plaque.

Most commonly, the plaque grows slowly, never causing a problem. In fact, most are never discovered. The arteries in the brain adjust to the slow narrowing, and no symptoms occur.

However, for unclear reasons, plaques can also become inflamed and unstable. If a plaque ruptures, the dangerous material in its centre is exposed to blood flowing by. As a result, a blood clot forms, which can rapidly block the artery. The brain tissue downstream is starved of blood and nutrients, and dies within hours.

Atherosclerosis and strokes: Reduce the risk

As a cause of strokes, heart attacks or other diseases, atherosclerosis has the same risk factors. It’s good to know them:

• High blood pressure (the most important risk factor for stroke)
• Cigarette smoking
• Diabetes
• Abnormal cholesterol levels
• Diet high in saturated or trans fats, low in fruits and vegetables
• Physical inactivity
• Obesity.

The best way to prevent a stroke is to control these risk factors. If you've already had a stroke or other form of atherosclerosis, reducing your risk is even more important.