Coronary Artery Bypass Grafting (CABG) is a heart surgery procedure in which one or more blocked coronary arteries are bypassed with a blood vessel graft to restore normal blood flow to the heart muscle. The grafts are usually taken from the patient’s chest (thoracic artery), leg (saphenous vein), or forearm (radial artery). The graft creates a new path to divert blood around the blockage and allow it to reach the oxygen-deprived heart muscle. CABG surgery is widely performed in the United States, and an estimated 800,000 CABG surgeries are performed worldwide each year.
CABG surgery is used to:
• Restore normal blood flow to the heart muscle
• Relieve the symptoms of coronary artery disease (including chest pain)
• Enable the patient to resume a normal lifestyle
• Lower the risk of a heart attack and other heart problems
Who Should Undergo CABG Surgery?
The cardiologist and cardiovascular surgeon work together with the patient and his or her family to determine the best treatment option. Factors they will consider include the extent of the cardiovascular disease, the severity of the symptoms, the patient’s age, the patient’s health status, and the patient’s other medical conditions.
Several types of bypass grafts can be used in CABG 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 or internal thoracic arteries in the chest are the most common bypass grafts used because they have shown the best long-term results. They have their own oxygen-rich blood supply, so in most cases, these arteries can be kept intact at their origin and then sewn to the coronary artery below the blockage. If the surgeon also removes the mammary artery from its origin, it is called a “free” mammary artery. Over the last decade, more than 90% of all CABG patients received at least one internal artery graft.
• The radial artery in the forearm is another commonly used graft. Careful pre- and intraoperative tests determine if the radial artery can be used; if it is, the patient may be required to take a calcium channel blocker medication for several months after surgery to prevent the artery graft from collapsing. Some patients report wrist numbness immediately after surgery, but long-term sensory loss or numbness is uncommon.
• A Saphenous vein from the thigh can be used as a bypass graft. 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, resulting in less scarring and faster recovery.
• The gastroepiploic artery to the stomach and the inferior epigastric artery to the abdominal wall are less commonly used for grafting.
CABG surgery generally lasts from 3 to 5 hours, depending on the number of coronary arteries affected. The cardiovascular anesthesiologist readies the patient for surgery. The surgeon removes the grafts and prepares the arteries for bypassing. 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. To bypass the blockage, the surgeon opens in the diseased coronary artery just below the blockage. If a saphenous vein or radial artery is used, one end is connected to the coronary artery and the other end is connected to the aorta. If a mammary artery is used, one end is connected to the coronary artery and the original end remains attached to the aorta. The graft is sewn into the open coronary artery, redirecting 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 one surgery.
Heart-Lung Bypass Machine
During CABG surgery, the heart may need to be stopped during the bypassing procedure to allow the surgeon to sew the new graft(s) securely in place. A perfusionist sets up and monitors the heart-lung bypass machine (“the pump”), which replaces the heart and lungs in circulating blood throughout the body while the heart is stopped.
Off-Pump or Beating Heart Bypass Surgery
Off-pump or beating heart bypass surgery is an option that allows surgeons to perform surgery on the heart while it is still beating. The heart-lung machine is not used, and the heart is not stopped during the procedure. Instead, the surgeon uses advanced operating equipment to stabilize and hold portions of the heart and then bypass the blocked artery in a highly controlled operative environment. Meanwhile, the heart keeps pumping and circulating blood to the body. Some patients are candidates for this option, and some are not. It usually depends on the location and severity of the heart disease.
Minimally Invasive Technique
Minimally invasive coronary artery bypass (MIDCAB) surgery is an option for patients who specifically require a left internal mammary artery (LIMA) bypass graft to the left anterior descending (LAD) coronary artery. Instead of the traditional open-heart incision, a smaller incision through the ribs is used. The benefits of minimally invasive bypass surgery include a smaller incision, a smaller scar, reduced risk of infection, decreased recovery time, and a shorter hospital stay.
After the grafts have been completed during the “on pump” procedure, the heart-lung machine is turned off, the heart resumes beating on its own, and the blood flow returns to normal. Temporary pacing wires and a chest tube to drain fluid are inserted before the sternum is closed with special wires. Then the chest is closed with either internal stitches or traditional external stitches. A temporary pacemaker is sometimes attached to the pacing wires to regulate the heart rhythm if needed. The patient is transferred to an intensive care unit for close monitoring 1 to 2 days after surgery. This includes continuous heart, blood pressure, and oxygen monitoring and frequent checks of vital signs and other parameters. After the patient is transferred to the nursing unit, the hospital stay lasts 3 to 5 more days.
Full recovery from CABG surgery takes 2 to 3 months. Most patients are able to drive within 3 to 8 weeks. The doctor provides specific and individual recovery guidelines, including instructions for incision care, general health care, activity restriction, cardiac rehabilitation, and return to work after surgery. CABG surgery does not prevent coronary artery disease from recurring; therefore, lifestyle changes and prescribed medications are strongly recommended to reduce this risk.