Coronary heart disease is also sometimes known as coronary artery disease or in laymans terms, heart disease. Coronary heart disease is the leading case of death for both sexes and strikes approximately 13 million Americans every calendar year. Coronary heart disease is what is known as atherosclerosis of the coronary arteries. It takes place when the arteries become congested with fatty plaque. They then narrow, making it difficult for blood to freely flow through. Without the proper supply of blood to and from the heart through the arteries, the heart quickly becomes depleted of both essential nutrients and oxygen, which affects its functioning.

The coronary arteries can easily be compared to tubes that are hollow. Inside of the arteries the surface is smooth and very elastic which makes the passage of blood a very simple and efficient process. During the adolescent years, fat deposits begin to build up in the walls of the blood vessels very slowly. As the years pass the fat builds up even more and too much can cause problems with the walls. The blood vessels respond by attempting to start the healing process. The cells of the blood vessel walls release chemicals that cause the surface of the walls to become very sticky.

After this process begins, other things such as calcium, proteins and inflammatory cells began to stick to the blood vessel walls as they pass through. The fat along with everything else that ends up sticking to the walls is known as plaque. The plaque gets thicker and thicker and eventually causes the arteries to harden, which is known as atherosclerosis.

The deposits of plaque are hard on the exterior but have a soft, mushy consistency to the interior. It is possible for the hard exterior to tear or crack and this can leave the interior exposed and vulnerable. If this occurs then platelets (which are particles shaped like discs that help make clotting of the blood possible) rush to the spot and the result is blood clots developing around where the plaque has built up. This is not good because it results in the arteries narrowing to an even greater extent. In some cases the blood clot will come apart and the supply of blood will return to normal. However this is not always the way it happens.

As time passes a coronary artery that is narrowed due to plaque will sometimes develop a new set of blood vessels that manage to get around the blockage in the blood vessel and can allow blood to freely reach the heart. This is often not so when stress is great or when there is increased exertion. In this case the new arteries that have developed may not be strong enough yet to transmit blood to the heart.

In extreme cases, a blood clot may make it impossible for blood to reach the heart at all. This is known as acute coronary syndrome. The three heart conditions that fall under this category include unstable angina, non-ST segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI).