Coronary artery bypass grafting (or CABG, pronounced "cabbage") is an "open heart" surgical procedure in which one or more blockages in a coronary artery are bypassed — with a blood vessel graft harvested from another part of the patient's body — to restore normal blood flow to the heart.
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In a typical CABG surgery, a blood vessel graft is transplanted from an artery or vein located in the patient's chest (from the thoracic artery), leg (saphenous vein) or arm (ulnar or radial artery). The graft serves as a detour route around the obstruction in the coronary artery.
Nearly one half million CABG procedures are performed each year in the U.S., making it one of the nation's most common major operations.
The Goals of CABG
CABG is performed to relieve symptoms of heart disease (coronary artery disease) and to lower the risk of a heart attack or other heart problems. It is recommended for patients who suffer from:
- Disease of the left main coronary artery, or all three major coronary arteries.
- A defective left ventricle.
- Severe angina (chest pain) that does not respond to medication.
Patients who do not improve with medication or balloon angioplasty may be appropriate candidates for CABG.
How CABG Is Performed
After general anesthesia is administered, a CABG procedure begins with the surgical team removing the appropriate vein or artery for grafting. The location and amount of arterial blockage, as well as the size of the coronary arteries, can influence the decision concerning the type of vein or artery to be harvested.
An internal thoracic artery (ITA) is commonly used in CABG grafting. Because an ITA is connected to the aorta at one end, it offers a nutrient-rich supply of blood. The other end of the ITA is sewn into an opening on the coronary artery, below the site of the blockage.
The saphenous vein of the interior leg is used commonly in emergency situations, because it can be harvested more quickly. Likewise, because ITAs have limited length, a saphenous vein graft can be used when a blockage is situated further away from the coronary arteries.
In traditional CABG, the surgical team will make a six- to eight-inch incision down the front of the chest, through the breastbone, to access the site of blockage. Called a median sternotomy, this incision offers a very good view of the heart.
However, as technology and techniques have evolved, many patients have are candidates for minimally invasive coronary artery bypass (MIDCAB) techniques involving endoscopy, robotic surgery and keyhole approaches.
For example, in "port-access" CABG, the surgical team will create small incisions in the chest, known as "ports," and use special instruments to perform the surgery. The procedure is viewed on video monitors, rather then directly.
Such techniques involve a smaller incision, less scarring, reduced risk of infection and bleeding, as well as shortened hospital stay and recovery time.
On-Pump CABG Surgery with a Heart-Lung Machine
Traditionally, CABG has relied on a procedure called cardiopulmonary bypass, or on-pump CABG. The heart is stopped, and the main aorta is clamped off, so that bypass grafts can be connected to the aorta. Surgeons are able to operate on a motionless, blood-free heart.
In on-pump CABG, a heart-lung machine keeps the patient alive by mechanically doing the work of the heart and lungs. Plastic tubes are inserted in the right atrium of the heart (which pumps oxygen-deprived blood to the lungs for oxygenation), diverting blood to the heart-lung machine's membrane oxygenator. There, carbon dioxide is removed from the blood. Oxygenated blood is then returned to the body.
Alternative Off-Pump CABG on the Rise
More recently, thanks to technological innovations, "off-pump" surgery has become more widely adopted. This procedure does not use the heart-lung machine, and surgeons operate on the heart while continues to beat. Only the area of the heart where the blockage is located requires stabilization.
The off-pump approach may be best for patients who are at increased risk for complications related to CABG — for example, those who have a blood vessel disease, a history of stroke or compromised lung or kidney function. Many older patients — particularly female patients, who develop heart disease 10 years later than men, on average — can benefit from off-pump CABG, as well.
Risks of CABG
Every surgery involves some degree of risk. Specific surgical risks of CABG include bleeding, infection, stroke, kidney failure and need for repeat surgery. The potential for complications depends upon the patients' overall health, age, other medical conditions and smoking history.
The number of procedures required in conjunction with CABG — valve repair, aneurysm surgery or atrial fibrillation surgery, for example — can affect risk factors, as well. Your John C. Lincoln cardiologist will review these risks with you prior to surgery.
Recovery and Rehabilitation After CABG
Before surgery, your cardiologist will review the recovery process after surgery. The length and phases of recovery can vary, depending upon the type and complexity of the CABG procedure.
The rehabilitation process begins with exercise stress testing, which is prescribed four to six weeks after CABG surgery. Rehabilitation typically spans 12 weeks; patients perform monitored exercises for one hour, three times a week. Exercises gradually become more strenuous.
Patients are also counseled about the importance of lifestyle changes to reduce heart disease risk — smoking cessation, maintaining a healthy weight, and controlling blood pressure, blood cholesterol and blood glucose levels.
Long-Term Success of CABG
The vast majority of CABG surgery patients experience long-term success. The procedure can successfully eliminate chest pain symptoms and help patients feel more energetic. Not only does it prolong life, it can greatly improve quality of life.