What is a coronary artery bypass graft?

Indications and Procedures

Atherosclerosis is a disease in which fat deposits called plaque accumulate on the walls of arteries and restrict blood flow. Although plaque can form in any arteries in the body, the effect is most noticeable in the coronary arteries, which supply blood to the heart muscle. Since the heart must pump continuously, it needs a steady supply of oxygenated blood. When the plaque in a coronary artery gets too thick, an area of the heart muscle will not receive enough blood, resulting in a condition called ischemia. The result is often chest pain called angina. Patients with angina are high risk for having a heart attack.

To alleviate angina and restore sufficient blood flow to the heart muscle, coronary artery bypass graft
surgery
may be performed. The patient is given general anesthesia for the procedure. The breastbone or sternum is sawed in two, and the chest is opened to expose the heart. At the same time, an assistant removes a healthy vein from an arm or leg. Most commonly, the saphenous vein from the upper leg is used. The heart is stopped and the patient is put on a heart-lung bypass machine that pumps the blood during the surgery. While the heart is stopped, the surgeon cuts the coronary artery above the blockage, and the healthy vessel which was removed from another part of the body is attached. Then the coronary artery is cut below the blockage and the other end of the healthy vessel is attached. This procedure effectively reroutes the blood flow
through the grafted vessel and around the blockage, thereby giving it the name bypass graft. Because the normal blood flow is restored, the angina is alleviated and the risk of heart attack is decreased. Another approach is to use the internal mammary artery, which is already attached to the aorta, for a blood source. Only one incision below the blockage needs to be made to establish good blood flow. After the bypass is completed, the heart is restarted and the machine is removed. The sternum is wired together and the incision is sutured.

Uses and Complications

Coronary artery bypass surgery is used to restore sufficient blood flow through a coronary artery that is narrowed or blocked with plaque. In patients with coronary artery disease it is common to have more than one artery narrowed or blocked. In this case, multiple bypasses may be completed in one surgery. Double, triple, and quadruple bypass surgeries are common. In these cases, the grafting procedure is repeated as many times as necessary to bypass all narrowed or blocked arteries.

One major problem for postoperative cardiac patients who have had bypass surgery is the threat of additional blockages developing. Sometimes patients need to have additional bypass surgeries several years later to bypass new blockages that have developed. Therefore, after surgery most patients will be referred to a cardiac rehabilitation
program, or cardiac rehab. In cardiac rehab, patients learn to exercise safely, eat right, and manage stress better. By making lifestyle changes patients can delay or prevent the development of additional plaque obstructions.

Perspective and Prospects

Bypass graft surgery is one way to restore blood flow through a blocked coronary artery. It has been widely used since the 1970s and has been safe and effective. However, it is a major surgical procedure that causes great discomfort to the patient. With advances in technology that are less invasive, such as cardiac catheters, other options are now available.

A procedure that competes with coronary artery bypass surgery is angioplasty. Instead of a major incision through the chest, angioplasty uses a catheter inserted through a small incision in an arm or the groin. The catheter is run through the blood vessels and into the heart. When the catheter reaches the narrowed area, the surgeon inflates a small balloon that compresses the plaque against the wall of the artery. Like bypass surgery, this procedure also improves blood flow to the heart muscle. Unfortunately, not all patients are good candidates for angioplasty and the more invasive bypass surgery must be used. As technology continues to improve, however, more patients will be able to have angioplasty.

Bibliography

Chizner, Michael A. Clinical Cardiology Made Ridiculously Simple. 4th ed. Miami: MedMaster, 2012.

Health Library. "Coronary Artery Bypass Grafting." Health Library, September 26, 2012.

MedlinePlus. "Coronary Artery Bypass Surgery." MedlinePlus, June 10, 2013.

NIH National Heart, Lung, and Blood Institute. "What Is Coronary Artery Bypass Grafting?" NIH National Heart, Lung, and Blood Institute, February 23, 2012.

Rippe, James M. Heart Disease for Dummies. Hoboken, N.J.: Wiley, 2004.

Sheridan, Brett C., et al. So You’re Having Heart Bypass Surgery. Hoboken, N.J.: John Wiley & Sons, 2003.