Coronary artery disease is the leading cause of death in the United States. Nearly five million people have evidence of coronary artery disease, and half a million die of it each year. Atherosclerosis, often called hardening of the arteries, is the most common type of coronary artery disease. Fat, cholesterol, and other cellular debris form deposits (plaque) along the inner walls of the arteries, which can narrow or completely block blood flow through the arteries to the heart muscle. The resultant loss of oxygen causes a heart attack. Heart attacks are not a consequence of old age: 45% occur in people under 65 and 5% in people under 40.
The blood circulating inside the heart does not supply the heart muscle itself with oxygen and nutrients. Rather, it is the blood vessels on the surface of the heart, called the coronary arteries, that nourish the heart muscle. Blocked or severely narrowed coronary arteries can be bypassed with healthy blood vessels to restore blood flow to the heart muscle. Coronary artery bypass grafting is one of the most commonly performed operations in the United States. The procedure is safe and highly effective when used appropriately.
Although it requires surgery, the coronary artery bypass operation usually offers the best long-term results for patients with obstructed coronary arteries. Newer non-surgical technologies are very exciting and can be used in many patients. However, the bypass operation still remains the most accepted form of treatment.
Bypass surgery may be recommended in patients who are suffering from disabling chest pain - angina - that cannot be treated with medication or angioplasty. These patients usually have abnormal electrocardiograms on exercise testing and significant obstructions in one or more of the coronary arteries. A 50% or greater blockage in the left main artery is a specific indication for operation.
Bypass surgery improves heart function, decreases the chances of a heart attack, and improves the patient's quality of life. Symptoms of angina are relieved in 80% of patients.
To detour blood around the obstructions in the coronary arteries, either a saphenous vein taken from the leg or the internal mammary artery (IMA) beneath the breastbone is used for the graft. The surgeon decides how many bypass grafts will be necessary before the operation. During the surgery, when the condition of the arteries can be examined directly, the surgeon may attach more or fewer bypasses than planned. (NOTE: The surgeon should be told before surgery if the patient has had procedures on the leg veins in the past, such as vein stripping.)
If a saphenous vein graft is used for bypass, it is first attached to the aorta and then to the coronary artery below the blockage. When the IMA is used, it remains attached at one end to its origin (the subclavian artery), and the other is then sewn to the coronary artery below the blockage. When one of these vessels is relocated to the heart, other veins or arteries in the donor area take over to circulate blood to the surrounding tissues in the leg or chest wall.
Surgery usually takes two to three hours. Generally it is more difficult and time consuming if the patient has had heart surgery in the past.
Patients are hospitalized for 4-5 days (including one to two days in the intensive care unit immediately after surgery), depending on how the body responds to the surgery and on the healing of the incisions over the breastbone and the legs, if saphenous veins were taken for the bypass.
Treatment of the blocked arteries is only the first step in restoring good health. Bypass surgery does not cure the underlying condition that caused the problem to develop. Further medical evaluation, treatment, and changes in lifestyle to reduce risk factors for heart attack are essential. These changes may include exercising, adopting a healthy diet, controlling blood pressure and weight, lowering cholesterol levels in the blood, and quitting smoking.