DISEASE OF CORONARY ARTERY

Disease can strike any part of the heart. However, the term heart disease usually means coronary artery disease (CAD), the most common form of heart disease. The condition affects the blood vessels that nourish the heart itself. CAD narrows the coronary arteries and so reduces the blood supply to the heart. About 5 per cent of the blood pumped from the heart goes directly to the coronary arteries. The blood carries the oxygen and dissolved nutrients (foods) the heart needs to do its work. The heart can store most nutrients. But it cannot store oxygen and needs a constant supply. Coronary artery disease may affect the heart's ability to pump by reducing or stopping the oxygen. Some people with CAD suffer severe pain. Others feel no pain and do not even know they have a heart problem. If the disease worsens, a heart attack may result. A heart attack damages the heart muscle or may even cause sudden death. Most cases of CAD can be treated, but the disease should be diagnosed (identified) as soon as possible.


Risk factors. Cardiologists cannot say for certain who will be stricken with coronary artery disease. However, medical research shows that certain conditions and habits may lead to the disease. Doctors call those conditions and habits risk factors. Some risk factors fall beyond a person's control. For example, CAD strikes more men than women and older people more than younger ones. In addition, the disease may run in a person's family. Several other risk factors involved in coronary artery disease can be controlled. The most important risk factor is the amount in the blood of a fatty substance called cholesterol. The higher a person's cholesterol level is, the more likely coronary artery disease will strike because the fatty deposits narrow the blood vessels. People can control the blood cholesterol level by reducing the amount of cholesterol and animal fats in the diet. See CHOLESTEROL.

Other controllable risk factors that may cause coronary artery disease include high blood pressure and cigarette smoking. High blood pressure forces the heart to work harder, which may bring on a heart attack. People can lower their blood pressure by losing weight, exercising, and eating less salt. Certain medicines also help reduce high blood pressure. Cigarette smokers are more likely to have CAD than nonsmokers. Heavy smokers run more than twice the risk of a heart attack than nonsmokers. But smokers who quit significantly reduce the risk of heart disease. Other risk factors that may contribute to the development of coronary artery disease include diabetes, extreme fatness, and stress.

Regular physical examinations often reveal the development of controllable risk factors. Doctors may then advise patients to quit smoking or to follow a specific diet to control high blood pressure, the cholesterol level, or weight.Causes.Nearly all coronary artery disease results from arteriosclerosis--a hardening, thickening, and loss of elasticity of the artery walls. In most cases, the inner layer of the artery wall becomes damaged, causing a form of arteriosclerosis called atherosclerosis. The inner walls of healthy arteries are smooth, and so blood flows easily. But in atherosclerosis, deposits of fats and calcium build up on the inner walls, hampering the blood flow through the artery. The fat and calcium deposits are called plaques. Plaques can completely block an artery and stop the blood flow. In addition, they can narrow an artery and so reduce blood flow enough to form a thrombus (blood clot). Plaques often crack, releasing substances that also can lead to blood clots. If a blood clot blocks a coronary artery, it causes a heart attack. A blood clot that occurs in an artery in the brain causes.