Atherosclerosis - The fatal plug in your arteries

Dateline: 07/06/97

Why is an atheromatous plaque dangerous ?

An atheroma initially forms in the inner lining of the artery - a layer called the tunica intima. Over a period of time, it grows and begins to encroach upon the lumen or cavity of the artery. It thus makes the artery narrow.

Since the volume of blood flow across a tube like an artery depends closely on the cross-sectional area of the tube, this narrowing causes a decrease in blood flow in the diseased artery. As a consequence, the part of the body supplied by that artery gets less blood and oxygen and nutrients than usual.

For example, if a coronary artery is affected, the heart muscle gets less nourishment, and cannot perform it's work normally.

On the other hand, if the plaque grows outwards away from the cavity of the artery, it weakens the wall of the artery by destroying the muscle layer in it. As a result, the artery wall cannot withstand the high pressure inside it, and it starts to dilate and become thin and stretched out - a condition called "aneurysm". This is dangerous because beyond a certain limit, the aneurysm will rupture due to the high pressure inside it.

And then there are complications of the plaque itself !

A long standing plaque will begin to deposit calcium within it, and this makes the artery extremely stiff and hard.

Ulceration is a dangerous complication. The inner wall of an artery is normally very smooth and allows blood to flow without any friction in a stream-lined manner. When a plaque forms, it roughens the inner surface causing turbulence in blood flow. After some time, the lining of fibrous tissue over the plaque may be eroded by this turbulent flow, and the inner core of the plaque is exposed to the blood stream.

When blood is exposed to this fatty core, it is stimulated to clot or harden, and this may cause the blood vessel to suddenly become totally blocked (thrombosis). When this happens in a coronary artery, there is a sudden decrease in blood flow to heart muscle which causes a heart attack (myocardial infarction).

Read more about atherosclerosis:

• How is an atheroma formed ?
• What are the risk factors for atherosclerosis ?