What Is Atherosclerosis?

The narrowing and hardening of blood vessels-arteries due to deposits of plaque is called atherosclerosis. Plaque is formed due to high blood cholesterol levels, sedentary lifestyle and various other conditions. In this article we will discuss the development of atherosclerosis. For basics about plaque and heart disease please  go to Heart Disease Page.  

How does atherosclerosis develop?

Atherosclerosis begins with an injury to the lining of the wall of an artery.  After an injury occurs, white blood cells such as monocytes and macrophages, together with LDL cholesterol, start accumulating along the inner layer of the artery and its muscle layer. This irritation induces multiplication of smooth muscle cells. Foam cells are formed in the process and eventually plaque is formed. Platelets as well as other blood clotting agents cause platelet aggregation (Due to stickiness  of a certain types of red blood cells) and form a thrombus or clot.

A clot thus formed can continue growing until it totally blocks an artery, cutting off the blood supply to a vital organ like the heart or a part of the brain.  A clot may also break off from the lining of the artery and get lodged elsewhere further downstream.  This may result in a heart attack if the artery in question happens to be a coronary artery  or stroke if the clot completely blocks the blood and oxygen supply to a part of the brain.

What causes atherosclerosis?

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What factors boost development of atherosclerosis?

There are several factors thar accelerate the process of atherosclerosis:

1. Family history    

The risk for developing atherosclerosis and consequent cardiovascular disease  increases if there is a family history of this disease. However lifestyle modification such as heart healthy diet, exercise, quitting smoking , stress relief can alleviate the risk to some extent.

Although people can have heart disease without having high cholesterol levels, but in majority of people high cholesterol and especially high bad cholesterol levels (LDL) in the blood significantly raises the chances of atherosclerosis and eventually heart disease. Sedentary lifestyle plays a major role in raising bad cholesterol levels. Genetic make up of an individual takes precedence over lifestyle. That is the tendency to have high bad cholesterol levels runs in the families of some people. Blood cholesterol levels can be lowered in these individuals by medicines like the statins.

3.  Low HDL cholesterol and high triglyceride levels

This type of lipid profile is slightly different from high total and LDL cholesterol. It is possible that someone may have both patterns of lipid profile.  This pattern of Low HDL cholesterol and high triglyceride levels is associated with insulin resistance and metabolic syndrome (syndrome X). Approximately 30% population gets affected by this pattern. Also, genetic dependence is stronger in this pattern. As mentioned in the metabolic syndrome (syndrome X) page, diabetes and hypertension are usually associated with this pattern. As a treatment for this pattern of lipid profile, lifestyle modification is more effective than other treatments.

4. High levels of homocysteine in the blood

Homocysteine is an amino acid. When you do not get sufficient vitamin B6 and folic acid, homocysteine in the blood rises. This risk factor is hereditary. Such genetically predisposed individuals require higher levels of folic acid than the RDA (RDA for folic acid is 400 micrograms.) Rise in  homocysteine level in the blood is an independent risk factor for atherosclerosis. That is, they have no direct correlation to blood cholesterol levels.

5. Smoking 

The habit of smoking is alone capable of accelerating the process of atherosclerosis, even if all other risk factors are nullified. The habit of smoking should be immediately quit.

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