Coronary artery bypass graft (CABG) is a surgical procedure done on patients with narrowing or occlusion of coronary artery, which supplies the cardiac musculature. More recently the term aortocoronary bypass (ACB) has come into popular use. The coronary arteries can get occluded by atheromatous plaque. Plaque is formed by cholesterol crystals, fats, clumped cells and calcium.
This surgical procedure involves bypassing the narrowing or occlusion in the coronary artery by using a vascular graft from elsewhere in the patient’s body. The surgery uses a piece of a vein from the leg or artery from the chest or wrist. The surgeon attaches this to the coronary artery above and below the narrowed area or blockage. Bypass surgery improves the blood flow to the heart with a new route, or “bypass,” around a section of clogged or diseased artery. Several alternative treatments for coronary artery disease exist. They include:
- Medical management (anti-anginal medications plus statins, antihypertensives, smoking cessation, tight blood sugar control in diabetics)
- Percutaneous coronary intervention (PCI)
There are some specific conditions where CABG is indicated.
- Disease of the left main coronary artery (which supplies the left ventricular area of heart with maximum musculature)
- Disease of all three coronary vessels (multivessel disease)
- Diffuse disease not amenable to treatment with a Percutaneous Coronary Intervention (PCI)
The patient is prepared for the procedure and brought to the operating room.
- Patient is anaesthetized by an experienced anesthetist.
- An endotracheal tube is inserted and secured by the anesthetist and mechanical ventilation is started.
- The chest is opened via a midline incision through the sternum and the heart is examined by the surgeon.
- The bypass grafts are harvested – frequent grafts are the internal thoracic arteries (from the chest), radial arteries (from forearm) and saphenous veins (from lower limb). When harvesting is done, the patient is given heparin to prevent the blood from clotting.
- If the case is “on-pump”, the surgeon uses cardiopulmonary bypass (CPB). On pump surgery involves the stopping of the beating heart and its function taken over by CPB.
- One end of each graft is sewn on to the coronary arteries beyond the blockages and the other end is attached to the aorta
- The heart is restarted; isolated from the CPB.
- Protamine is given to reverse the effects of heparin.
- The sternum is wired together and the incisions are sutured closed.
- The patient is moved to the intensive care unit (ICU) to recover. After awakening and stabilizing in the ICU (approximately 1 day), the person is transferred to the cardiac surgery ward until ready to go home (approximately 4 days).
Prognosis of the procedure results on a number of factors. But on an average successful CABG has a life of 10 -15 years. Age at CABG is the most important factor. Younger age group in the absence of other risk factors has the best prognosis. After CABG the patients are to take certain precautions for eight to 12 weeks to reduce the risk of opening the incision. First, patients need to avoid using their arms excessively, such as pushing themselves out of a chair or reaching back before sitting down. Second, patients should avoid lifting anything in excess of 2-5kg. Finally, patients should avoid overhead activities with their hands, such as reaching for clothes from the top shelf. Minimally invasive CABG Alternate methods of minimally invasive coronary artery bypass surgery have been developed in recent times. Off-pump coronary artery bypass surgery (OPCAB) is a technique of performing bypass surgery without the use of the heart-lung machine. Further improvements to OPCAB have resulted in minimally invasive direct coronary artery bypass surgery (MIDCAB), a technique of performing bypass surgery through a small incision of 5 to 10 cm incision.