What Is Coronary Artery Bypass Surgery?

Coronary artery bypass surgery is done to provide new blood flow around partially or completely blocked coronary arteries. With a new open "bypass system" the heart can now receive its much needed blood supply.

Coronary artery bypass surgery is performed to provide relief of angina, to improve the pumping ability of the heart muscle, to prevent heart attacks, and to reduce the use of heart medications, all of which should improve a person's quality of life. The indications for surgery vary, depending on each patient's symptoms and findings at the time of heart catheterization. Your surgeon and cardiologist will discuss the reasons for recommending surgery to you.

Figure 1

The concept of coronary artery bypass surgery is very simple. The blocked arteries are bypassed using saphenous veins (which are from the leg) the internal mammary artery (the vessel that runs along the inside of the breast bone), or an arterial graft from other areas of the body. The bypass grafts veins are used by the surgeon as an alternate vessel to deliver blood to the heart muscle below the point of the blockage. The surgery reroutes the blood flow to supply areas of the heart muscle not receiving enough blood (See Figure 1).

Figure 2

How long do the vein grafts last? Over time, bypass grafts can become narrowed or occluded just like the coronary arteries. The internal mammary artery grafts last longer than vein grafts in most cases. Most patients who require more than one or two bypasses will receive a combination of an internal mammary artery graft plus several vein grafts. Over 90% of internal mammary artery grafts are still open after 10 years. About 65% of vein grafts are still open after 5 years. If bypass grafts become narrowed at some time after surgery, many can be treated with balloon angioplasty, stent, etc. Some patients may require repeat bypass procedures.

The most important factor in keeping bypass grafts open after surgery is reduction of risk factors. One of the most important risk factors is family history which cannot be controlled. Other risk factors which can be controlled include smoking, diabetes, high blood pressure, cholesterol, obesity, and exercise. 

After bypass surgery, all patients receive education on risk factor modification.