What is Coronary Artery Disease?

The heart consists of four chambers: the left atrium and right atrium (upper chambers) and the left ventricle and right ventricle (lower chambers). The heart receives oxygen-depleted blood from the body, pumps it to the lungs to receive a new supply of oxygen, and then sends this oxygen-rich blood back into the body. The cycle repeats continuously.
           
Arteries carry blood away from the heart to the rest of the body. Veins carry blood from various parts of the body back to the heart. The coronary arteries that supply the heart muscle itself are especially important, because they carry oxygenated blood back to the heart to keep it working efficiently. Healthy arteries are soft and allow blood to flow smoothly and easily, without obstruction.

However, if an artery becomes clogged, blood cannot flow through it smoothly. High cholesterol, high blood pressure, and smoking can all contribute to a buildup of plaque (fatty substances and calcium) along the inner walls of the arteries. As plaque builds up, the space inside the artery becomes narrower.

As a result of narrowed arteries, blood flow to the heart becomes restricted. Therefore, the heart cannot receive enough oxygen. Narrow arteries can also contribute to the formation of blood clots. If an artery becomes completely blocked, you may have a heart attack (also called a myocardial infarction). Without the ability to receive oxygen from the blood, portions of the heart muscle may become permanently damaged.

When a coronary artery is blocked, your doctor may have to perform an operation to bypass the damaged portion of the artery and restore proper blood flow to the heart. The procedure is serious but not uncommon; more than half a million coronary bypass operations are performed each year.

What Takes Place During Surgery?

The formal name for heart bypass surgery is a coronary artery bypass graft, or CABG. In this operation, a healthy blood vessel from another part of the body is attached to the damaged artery, bypassing the blocked portion. This allows blood to flow freely to the heart again.

The blood vessels most commonly used for the bypass are the internal mammary arteries along the inside of the chest wall or the saphenous veins in the legs. The radial arteries in the arms are also sometimes used. These vessels can usually be spared without significantly affecting the blood flow to the rest of the body.

The surgeon will make a cut, or incision, down the center of the chest and then separate the breastbone (sternum). The heart is then stopped and cooled, during which time your blood is routed through a heart-lung machine. This part of the surgical procedure is called cardiopulmonary bypass. This machine supplies the body with oxygen and pumps it through the body during the operation.

The bypass vessel is removed from the chest, arm, or leg. One end of it is then sewn onto an opening in the coronary artery beyond the blockage(s). If a radial artery or saphenous vein is used, the other end is attached to the aorta (the large artery that comes out of the heart); if a mammary artery is used, the other end will already be attached to a branch of the aorta. This will allow blood to flow to the heart as it should.

After the bypass is completed, you will be removed from the heart-lung machine and your organs will once again take over. The surgeons will rejoin the breastbone and close the incision. The entire procedure usually takes about three to six hours.

Following Surgery

Cardiac bypass surgery is a major operation, and recovery takes time. Most patients spend a few days in the Intensive Care Unit (ICU) where they are closely monitored. During this time, chest tubes will collect blood and drainage, and a tube in the mouth and throat will help the patient breathe. When these devices are removed, the patient will be moved into a regular hospital unit and rehabilitation will begin. It will take time to regain strength and resistance to illness.

After about six to eight weeks, the breastbone itself will heal and you will be able to resume most of your normal routine. Expect followup visits with your doctor to monitor your progress throughout your recovery period. Your doctor will give you guidelines about how long to avoid driving, lifting, and other strenuous activities that could adversely affect your healing.