Coronary Artery Disease

Disease of the coronary arteries that supply oxygen and nutrients to the heart is the most common heart ailment. Coronary artery disease accounts for more than a third of all deaths among males in the United States between the ages of 35 and 55. It also strikes many women past the age of 50. Hypertension (high blood pressure), overweight, cigarette smoking, diabetes mellitus, excess cholesterol, triglycerides and other fats in the blood, and lack of regular exercise contribute to the chance of developing this disease.

Coronary artery disease is characterized by formation of one or more atheromas. These are fatty deposits of cholesterol that form beneath the inner lining of the artery and obstruct the passage of blood needed to nourish the heart muscle. This also sets up conditions for a blood clot in the coronary artery. Atheroma formation seems to run in families. However, eating foods rich in saturated animal fat and cholesterol are also contributing factors.

Many persons with coronary artery disease do not experience any symptoms. However, if the obstruction is bad enough, it may cause angina pectoris, myocardial infarction (heart attack), or heart enlargement and failure. Angina pectoris is a severe, squeezing chest pain that occurs when the coronary blockage prevents adequate oxygen from reaching the heart, especially during periods of exertion. Rest and medication often relieve the pain. Unlike a heart attack, angina is a temporary condition, and heart muscle is not destroyed.

Myocardial infarction is the medical term for a heart attack. When the coronary artery becomes so obstructed that the myocardium, or heart muscle, does not receive oxygen, the muscle tissue dies, or becomes infarcted. For many years doctors believed that the infarction was caused by a blood clot blocking the coronary artery. However, later studies revealed that most clots form in the artery after the infarction.

The first hours after a heart attack are critical because abnormal heart rhythms, or arrhythmias, may develop. Without swift medical intervention, death follows in three or four minutes after an attack. Patients are usually treated in the coronary care unit of a hospital for a few days to enable electronic monitoring of the heart rate and rhythm.

Repeated heart attacks can strain the remaining healthy heart muscle, leading to heart failure. As attacks destroy more and more heart muscle, the remaining muscle enlarges to compensate. Increased pressure in the weakened heart causes fluid to back up into the lungs. As a result, the heart output—that is, the volume of blood pumped out with each contraction—cannot keep pace with the body's oxygen demands.