Coronary heart disease, or CHD, refers to the narrowing of the coronary arteries that supply blood to the heart. CHD is a progressive disease that increases the risk of heart attack and sudden death.

What is going on in the body?

In order for the heart to pump as it should, the heart muscle needs a steady supply of oxygen-rich blood. This blood is delivered by the coronary arteries. Two main vessels branch out to supply blood to the entire muscle of the heart. The heart needs more oxygen during exercise and high levels of activity. Less is needed when the person is at rest.

Atherosclerosis means the fatty deposits that form under the inner lining of the blood vessels. When the coronary arteries become blocked, less blood can get through. The blockage can be small, or it may be large enough to fully obstruct blood flow. Blockage can occur in one or many coronary arteries.

Small blockages may not always affect the heart's performance. The person may not have symptoms until the heart needs more oxygen-rich blood than the arteries can supply. This commonly occurs during exercise or other activity. The pain that results is called stable angina.

If a blockage is large, angina pain can occur with little or no activity. This is known as unstable angina. In this case, the flow of blood to the heart is so limited that the person cannot do daily tasks without bringing on an angina attack. When the blood flow to an area of the heart is completely blocked, a heart attack occurs.

What are the causes and risks of the disease?

CHD affects people of all races. It can be caused by a combination of unhealthy lifestyle and genetics. Coronary risk factors that increase the risk of CHD are as follows:

Genetic factors that affect heart disease risk are beyond a person's control. These include a strong family history of the following: