According to Sabiston Textbook of Surgery, 500,000 coronary artery bypass graft--CABG--procedures are done yearly. Fifty to 75 percent of these surgeries have an uncomplicated postoperative course. The risk of suffering a complication is usually quite small, but when complications occur, they have significant morbidity. The most common risks of bypass surgery are stroke, renal failure and reoperation.
Stroke
The risk of stroke is 1.63 percent, according to Sabiston. The range of complications related to stroke can be very small and hardly noticeable to devastating destruction of the brain requiring long-term hospital care. A stroke occurs when the blood supply to the brain is interrupted, and brain cells die from lack of oxygen. Stroke is typically caused by an embolus that has broken loose from the aorta during cross clamping. Cross clamping is done when the patient is put on the coronary artery bypass machine. The cross clamp blocks blood from returning to the heart by clamping across the aorta. Occasionally, pieces of calcium break away from the lining of the aorta and go to the brain.
Kidney Failure
The cardiopulmonary bypass machine allows the surgeon to operate on a non-beating heart that is empty of blood. This machine takes the patient's blood and circulates it through tubing that eventually returns it to the patient. Because the blood cells are sensitive to the tubing, they react by forming cytokines that quickly spread through the body. Cytokines cause an inflammatory response and can affect any organ, but often cytokines damage the kidneys. Kidney damage can be slight or so severe that the patient requires dialysis for life. The risk of renal failure is 3.53 percent according to Sabiston.
Reoperation
Immediate reoperation occurs when the bypass grafts occlude acutely after surgery or significant bleeding occurs. According to Sabiston Textbook of Surgery, the risk of reoperation within 24 hours is 7.17 percent. Patients who are at risk for reoperation are older and have multiple medical problems. They are also exposed to platelet inhibitors prior to surgery, thus increasing the potential for significant bleeds. Patients who have emergency or salvage surgery are more likely to bleed and require reoperation than those whose surgery is scheduled.
References
- Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice, 16th Edition by Courtney M. Townsend (Editor), Mattox, B. Mark Evers, Daniel Beauchamp. 2009
- The Merck Manual Online Medical Library.com: Coronary Artery Bypass Grafting (CABG)
- The American Heart Association: Reoperation for Bleeding among 528,279 Patients Undergoing Coronary Artery Bypass Surgery: The Society of Thoracic Surgeons National Database Experience
