What is coronary artery bypass graft (CABG) surgery?

Types of coronary artery bypass grafts

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 (thoracic), leg (saphenous) or arm (radial). The graft goes around the blocked artery (or arteries) to create new pathways for oxygen-rich blood to flow to the heart.

The goals of the procedure are to relieve symptoms of coronary artery disease (including angina), enable the patient to resume a normal lifestyle and to lower the risk of a heart attack or other heart problems.

Coronary artery bypass surgery is widely performed in the United States. It is estimated that more than 800,000 coronary artery bypass graft surgeries are performed worldwide every year.

The American Heart Association reports that 467,000 cases of coronary artery bypass surgery were performed on 268,000 patients in the United States in 2003.

Who is eligible to receive coronary artery bypass graft surgery?

The decision to prescribe medical treatment, invasive procedures or cardiac bypass surgery depends on several factors including the extent of cardiovascular disease, the severity of symptoms, your age and other medical conditions. The cardiologist (heart specialist) and surgeon will determine the best method of therapy for each patient.

What happens during the cardiac bypass surgery?

The surgery generally lasts from 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.

Graft Preparation

Grafts used for bypass

There are several types of bypass grafts that can be be used in cardiac bypass surgery. The surgeon  decides which graft(s) to use, depending on the location of the blockage, the amount of the blockage and the size of the patient’s coronary arteries.

• Internal mammary arteries [also called
  IMA grafts or internal thoracic arteries (ITA)] 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 then 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 (arm) artery is another common type of arterial graft.  There are two arteries in the arm, the ulnar and radial arteries. Most people receive blood to their arm  from the ulnar artery and will not have any side effects if the radial artery is used. Careful preoperative and intraoperative tests determine if the radial artery can be used. If the radial artery is used as the graft, the patient may be required to take a calcium channel blocker medication for several months after surgery.  This medication helps keep the artery open. Some people report numbness in the wrist after surgery. However, long-term sensory loss or numbness is uncommon.
  
• The gastroepiploic artery to the stomach and the inferior epigastric artery to the abdominal wall are less commonly used for grafting.
  
• Saphenous veins can be used as bypass grafts. Minimally invasive saphenous vein removal   does not require a long incision. 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. Your  surgeon will decide if this method cardiac bypass surgery is a good option for you.

Surgical Procedure

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 procedure is repeated until all affected coronary arteries are treated. It is common for three or four  coronary arteries to be bypassed during surgery.

Before the patient leaves the hospital, the doctor or nurse will explain the specific bypass procedure that was performed.

Heart-Lung Machine

During surgery, 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. The heart’s beating is stopped so the surgeon can perform the bypass procedure on a “still” heart.

beating heart surgery

Off-pump or beating heart bypass surgery

Off-pump or beating heart bypass surgery allows surgeons to perform surgery on the heart while it is still beating. The heart-lung machine is not used. The surgeon uses advanced operating equipment to stabilize (hold) portions of the heart and bypass the blocked artery in a highly controlled operative environment. Meanwhile, the rest of the heart keeps pumping and circulating blood to the body.

Click here for more information about off-pump surgery

Minimally Invasive Technique

Minimally invasive coronary artery bypass (MIDCAB) surgery is an option for some patients  who require a left internal mammary artery (LIMA) bypass graft to the left anterior descending  (LAD) artery. A small incision is used.

In contrast, traditional CABG surgery requires a 6- to 8-inch incision down the center of the  sternum (breastbone) to provide the surgeon direct access to the heart. The benefits of  minimally invasive bypass surgery include a smaller incision (and a smaller scar), reduced risk of infection, decreased recovery time and shorter hospital stay.

Traditional incision

After the grafts have been completed during the “on pump” procedure, the heart-lung machine is turned off, the heart starts beating on its own, and the flow of blood returns to normal. Temporary pacing wires and a chest tube to drain fluid are placed before the sternum is closed with special sternal wires. Then the chest is closed with internal stitches  or traditional external stitches. Sometimes a temporary pacemaker is attached to the pacing wires to regulate the  heart rhythm until your condition improves.

The patient is transferred to an intensive care unit for close monitoring for about one to two days after the surgery. The monitoring during recovery includes continuous heart, blood pressure and oxygen monitoring and frequent checks of vital signs and other parameters, such as heart sounds.

Once the patient is transferred to the nursing unit, the hospital stay is about 3 to 5 more days.

Recovery

Full recovery from coronary artery bypass graft surgery takes around two months. Most patients are able to drive in about three to eight weeks after surgery. Your doctor will provide specific guidelines for your recovery and return to work, including specific instructions on activity and how to care for  your incision and general health after the surgery.

Lifestyle changes include:

• Quitting smoking
• Treating high cholesterol
• Managing high blood pressure and diabetes
• Exercising regularly
• Maintaining a healthy weight
• Eating a heart-healthy diet
• Controlling stress and anger
• Taking prescribed medications as ordered
• Participating in a cardiac rehabilitation program, as recommended
• Following up with your doctor for regular visits

Information on prevention and making lifestyle changes can be found at Cardiovascular Disease Prevention.