CAD is indeed a silent human killer. Although the disease process starts in coronary arteries early in childhood, it continues progressing very gradually through years/decades, and becomes significant enough only later in life, say at the age of 40, or earlier. The reason is that no symptom of the disease occurs till more than 50-60% of the surface area of the coronary arteries is involved. Out of sudden deaths, as a result of CAD, 50% patients may not have any symptom earlier, and such may be the cases which have never gone through tests for detection of CAD.



Hence such a fatal disease remains masked for a long time, but if one knows about it, it can be checked/arrested, and mortality in the prime years of life, when one is at the height of one's career, can be prevented.

There are two coronary arteries, right and left, which supply oxygenated blood to muscular walls of the heart. The left coronary artery divides into two main branches. Both right and the main branches of the left coronary arteries divide further into several smaller branches supplying blood to their respective portion of the heart. The lesion of CAD may occur either in the main blood vessel/branch, or in any of the smaller branches of the coronary arteries. The disease process may occur either at one place, or even at several places of the coronary arteries or its branches, i.e. in a person either the main vessel or many of the branches may be involved at the same time.

The heart, which is egg-shaped, is a hollow muscular organ (consisting of four chambers) and is about the size of a fist. It supplies oxygenated blood to the whole body which is necessary for its proper functioning. Even for its own working, the muscular walls of the heart need oxygenated blood which is supplied by the coronary arteries. Hence if coronary arteries are diseased, called CAD, their caliber will become narrow, and so less blood will flow through them. Thus the supply of oxygenated blood to the walls of the heart will suffer.

What is the cause of CAD?

In the walls of the coronary arteries, a fatty material gets deposited called atherosclerosis. It starts in early childhood, and as the years pass, this process of atherosclerosis continues, and ultimately the walls of the coronary arteries start thickening and their lumen starts narrowing. The process is so slow that in about the third decade a partial blockage of the lumen of the coronary arteries/its branches may manifest itself, and during the next 10 years i.e. in the fourth decade a complete blockage of the coronary arteries may occur. When the blockage is partial, less blood will flow in coronary arteries, and so less blood will be supplied to the muscular wall of the heart. And whenever there is less supply to the muscular wall of the heart, the patient experiences pain in the chest. The severity of pain has a direct relation to the blood supply to the wall of the heart. If the supply is adversely affected/suddenly cut off in the coronary arteries or one of its branches, the patient may get a severe pain in the chest called myocardial infarction or heart attack. In the beginning, the patient may get only temporary pain in the chest called angina pectoris.