Atherosclerosis: Build-up of plaque in the arteries

Atherosclerosis is a disease where the inside of the arteries are blocked by plaque. When the plaque breaks away, it can form blood clots that cause heart attacks.

Clinical Associate Professor Aaron Wong, Head and Senior Consultant, Department of Cardiology, National Heart Centre Singapore (NHCS), a member of the SingHealth group, shares, "There are many unknown factors which increase the risk of a heart attack. What we do not know, we cannot prevent or treat. But what we do know is that maintaining a healthy and active lifestyle is key for prevention.”

Atherosclerosis (plaque buildup): How does it happen?

Atherosclerosis – commonly known as the hardening of the arteries – is still something of a mystery. Exact causes are unknown but doctors say that unhealthy habits, such as heavy smoking and a fatty diet, greatly increase a person’s risk of developing it.

When plaque builds up in an artery, it narrows the artery and reduces blood flow,” explains Dr Wong. Plaque builds up when cholesterol, white blood cells, calcium and other substances accumulate on an artery wall. In time, the plaque can break off, causing a blood clot. If the clot is large enough, it can block blood flow through a coronary artery and cause a heart attack.

Dr Wong said that the narrowing of the arteries can affect the body in a spectrum of ways. For a start, the narrowing can be so gradual that the body’s natural compensation mechanism causes small capillaries to form, bridging the blockage before the artery is completely blocked.

This “natural bypass” prevents patients from having a heart attack even though an artery may be 100 per cent blocked. However, the patient may have angina – the feeling of pain or tightness in his chest during physical exertion – with the pain typically going away when he stops to rest.

When the plaque build-up in the artery suddenly ruptures, platelets in the blood will rapidly cover up the rupture, leading to a clot forming, which narrows the artery further. If blood flow is completely blocked, the affected muscle loses its oxygen supply and a heart attack occurs. If the blockage is not opened within 12 hours, the muscle supplied by that artery will be irreversibly damaged. Depending on its severity, a heart attack could lead to death.

Patients with atherosclerosis may show no symptoms for decades, until a sudden heart attack occurs.

Read on for risk factors and treatment options for atherosclerosis.

See page 3 to learn about atherosclerosis complications and how to prevent them.

Ref: R14

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