Atherosclerosis is a medical term that describes thickening and hardening of the arteries in the body. In this condition, fatty plaques and blood cells build up within the artery eventually leading to it becoming narrowed.
What happens in atherosclerosis?
To put it in very simple terms, in atherosclerosis, there is just deposition of fat, blood cells, smooth muscle cells and a variety of different products such as calcium on the inner lining of the blood vessels. These together form what is called an atherosclerotic plaque. The atherosclerotic plaque is firmly attached to the wall of the blood vessel and grows bigger and bigger with time.
At a point where the atherosclerotic plaque is large enough to occlude the lumen of the blood vessel, there is a significant reduction in the amount of blood that flows through the blood vessels. When atherosclerosis affects the arteries of the heart, the amount of blood that reaches the heart muscle can reduce dramatically. This is what is responsible for chest pain i.e. angina.
The entire process of atherosclerosis is triggered by damage to the inner lining of the blood vessels. On the inner surface of blood vessels are present a single layer of cells called the endothelial cells. The endothelial cells are responsible for maintaining the normal structure and function of the blood vessels.
In the presence of certain risk factors such as diabetes, high blood pressure, smoking and a family history of heart disease, the endothelial cells can get damaged. When this happens, numerous mediators are released into the bloodstream which attract towards the damage site blood cells and smooth muscle cells.
The blood cells, called platelets, form small clumps on the surface of the damaged endothelial cells. To this come and attach the bad cholesterol molecules which make these clumps a lot more bigger. Over the clump of fat tissue and blood cells starts to go smooth muscle cells which are present normally in the wall of the blood vessels.
This final clump of blood cells, fat cells and smooth muscle cells attract other cellular waste products along with molecules such as calcium and a thin fibrous clotting material in the blood called a fibrin. Together, this form the atherosclerotic plaque.
The problem with the atherosclerotic plaque
While the atherosclerotic plaque can be firmly attached to the blood vessel wall in a majority of cases, there are times when the plaque may break off and start to flow down the blood vessel. This plaque can occlude or the block the blood vessel and thus the blood supply to a part of the heart muscle. This can cause a heart attack.
In addition to just the plaque breaking off, there is also a possibility that the atherosclerotic plaque promotes the formation of a blood clot on it surface. This blood clot can become large enough to block the blood flow through the artery. This again can cause a heart attack.
In a nutshell, the presence of a large atherosclerotic plaque within the blood vessel increases the risk of a patient developing chest pain or a heart attack.
Heart attacks and strokes are similar
If a heart attack is caused by a reduction in blood flow to the heart muscle, stroke is caused by a reduction in blood flow to the brain. Atherosclerosis not only affects the arteries around the heart, it can also affect the blood vessels that supply blood to the brain (carotid artery and the similar blood vessels).
Similarly, atherosclerosis can affect the blood vessels that supply the muscles in the leg and can cause pain when walking. This is known as peripheral arterial disease and is usually seen in patients who smoke. Patients who have severe peripheral artery disease can develop gangrene.
It starts early
The worrying thing about atherosclerosis is that it actually starts in childhood. Our recent dietary changes and high incidence of risk factors have made this disease affect our children. It is therefore of vital importance that children be fed a healthy diet and get plenty of exercise from early days so that they may prevent the development of heart disease and stroke in the future.
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