The Coronary Artery Bypass Graft (CABG) is a heart surgery procedure in which one or more blocked coronary arteries are bypassed by a blood vessel graft to restore normal blood flow to the heart.
These grafts usually come from the patient’s own arteries and veins located in the chest, leg or arm.
The graft goes around the blocked artery (or arteries) to create new pathways for oxygen-rich blood to flow to the heart.
CABG relieves symptoms of coronary artery disease, enabling the patient to resume a normal lifestyle and to lower the risk of a heart attack or other heart problems.
The CABG generally lasts for three to five hours, depending on the number of arteries being bypassed.
After general anesthesia is administered, the surgeon removes the veins or prepares the arteries for grafting, from the patients’ chest (internal mammary artery), arm (radial artery) or leg (saphenous vein).
Depending on the location of the blockage, the amount of the blockage and the size of the patient’s coronary arteries, the surgeon will decide which graft to be used.
These grafts usually come from the patient’s own arteries and veins located in the chest, leg or arm.
The graft goes around the blocked artery (or arteries) to create new pathways for oxygen-rich blood to flow to the heart.
CABG relieves symptoms of coronary artery disease, enabling the patient to resume a normal lifestyle and to lower the risk of a heart attack or other heart problems.
The CABG generally lasts for three to five hours, depending on the number of arteries being bypassed.
After general anesthesia is administered, the surgeon removes the veins or prepares the arteries for grafting, from the patients’ chest (internal mammary artery), arm (radial artery) or leg (saphenous vein).
Depending on the location of the blockage, the amount of the blockage and the size of the patient’s coronary arteries, the surgeon will decide which graft to be used.
Figure 1: The heart, its sites of blockage and blood vessels used for grafting.
Internal mammary arteries are the most common bypass grafts used, as they have shown the best long-term results.
In most cases, these arteries can be kept intact at their origin because they have their own oxygen-rich blood supply, and can be sewn to the coronary artery below the site of the blockage. If the surgeon removes the mammary artery from its origin, it is called a “free” mammary artery.
Over the last decade, more than 90% of all patients received at least one internal artery graft.
The radial artery is another common type of arterial graft. If the radial artery is used, the patient may be required to take a calcium channel blocker medication for several months after CABG. This medication helps keep the artery open.
A few reports state that patients who have had their radial artery used feel numbness in the wrist after surgery. However, long-term sensory loss or numbness is uncommon.
Saphenous veins can be used as bypass grafts. One to two incisions are made at the knee and a small incision is made at the groin. This results in less scarring and a faster recovery.
The arteries least used for grafting are the gastro-epiploic artery to the stomach and the inferior epigastric artery to the abdominal wall.
To bypass the blockage, the surgeon makes a small opening just below the blockage in the diseased coronary artery.
If a saphenous (leg) or radial (arm) vein is used, one end is connected to the coronary artery and the other to the aorta.
If a mammary artery is used, one end is connected to the coronary artery while the other remains attached to the aorta.
The graft is sewn into the opening, redirecting the blood flow around this blockage.
The procedures are repeated until all affected coronary arteries are treated. It is common for three or four coronary arteries to be bypassed during surgery.
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Figure 2: The heart after CABG
During CABG, the heart’s beating is stopped so the surgeon can perform the bypass procedure on a “still” heart. The heart-lung bypass machine (called “on-pump” surgery) is used to take over for the heart and lungs, allowing the circulation of blood throughout the rest of the body.
Other than on-pump surgeries, off-pump or beating heart bypass surgeries are also present. This allows surgeons to perform the surgery while the heart is still beating. The heart-lung machine is not used, and the surgeon uses advanced operating equipment to stabilize portions of the heart while bypassing the blocked artery in a highly controlled environment. Meanwhile, the rest of the heart keeps pumping and circulating blood to the body.
Full recovery from CABG takes around two months. Most patients are able to resume daily activities in about three to eight weeks after surgery.
CABG does not prevent coronary artery disease from recurring, therefore lifestyle changes and prescribed medications are strongly recommended to reduce this risk.
Some of these lifestyle changes are, for example, quitting smoking, exercising regularly and eating a heart-healthy diet.
From reports of the American Heart Association, out of 467,000 cases of CABG performed in the United States in 2003, 268,000 were on patients suffering from coronary artery disease. This illustrates the effectiveness of the CABG.
All above information is adapted from Cleveland Clinic Heart Center
Figure 1 is obtained from Intensive Care Coordination and Monitoring Unit (ICCMU)
Figure 2 is obtained from State of New York (SUNY) Upstate Medical University
An off-pump CABG, or OPCAB, allows a surgeon to perform a bypass surgery without stopping the heart.
http://video.about.com/heartdisease/OPCAB.htm
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