Coronary Artery Bypass Surgery

Coronary artery bypass surgery,  also known as coronary artery bypass graft  surgery or bypass surgery, is a surgical procedure to improve blood flow and oxygen supply to the heart.  

Some facts about Coronary Artery Bypass Surgery:

• Coronary heart disease can be treated by Coronary artery bypass surgery.
• The blood around narrowed or clogged parts of the major arteries are diverted to improve blood flow and oxygen supply to the heart.
• The normal blood flow to an obstructed coronary artery can be restored as a normal coronary artery does not transports blood through the main circulatory system, but to the heart muscle itself.
• A angina that is poorly managed by maximum tolerated anti-ischemic medication can be prevented by CABG. Angina is chest pain because of restricted supply of oxygen rich blood to the heart.
• Left ventricular dysfunction can be prevented or relieved and the risk of death can be reduced.
• Myocardial infarction can not be prevented by CABG.
• CABG is often recommended when coronary arteries have a 50 to 99 percent obstruction which is typically due to arteriosclerosis, atherosclerosis, or both.
• Your chances of having a heart attack can be reduced by a Coronary Artery Bypass Surgery.

Necessity of Coronary Artery Bypass Surgery:

• The heart needs a constant supply of blood like all other organs in the body which is supplied by two large blood vessels called the left and right coronary arteries. Over time, fatty deposits called plaques are build up in the arteries making them narrowed and hardened.
• This process is known as atherosclerosis in which thickening, loss of elasticity, and calcification of the arterial wall happens resulting in narrowing in the affected coronary artery.
• A yellowish plaques of cholesterol, lipids, and cellular debris are deposited into the inner layer of the wall of coronary artery in the process of atherosclerosis, resulting in a partial obstruction in the affected artery.
• The blood flow will be limited in either of the cases if it causes a cross-sectional narrowing of at least 50%.
• The chances of developing coronary heart disease increase with age and also if you smoke, are overweight or obese or have a high-fat diet.
• CABG is required when there is a  possibility of one of the plaques in the coronary artery rupturing or splitting, creating a blood clot which can can trigger a heart attack as the blood supply to the heart can be blocked because of blood clot.

Procedure of Coronary Artery Bypass Surgery:

• An intravenous and arterial lines will be placed and an analgesic, usually fentanyl, will be injected intravenously once the patient is moved onto the operating table. It is followed by giving an induction agent usually propofol or etomidate within minutes.
• An endotracheal tube is inserted and mechanical ventilation will be started.
• An inhaled volatile anesthetic agent such as isoflurane will be used to maintain general anaesthesia.
• The heart will be examined by the surgeon by opening the chest through a median sternotomy.
• A new blood vessel known as a graft that are taken from another part of the body, usually the chest, leg or arm will be attached to the coronary artery above and below the narrowed area or blockage.
• The bypass grafts are removed from the internal thoracic arteries, radial arteries and saphenous veins.
• The patient will be given heparin to inhibit blood clotting ater removing the bypass grafts.
• The surgeon places devices to stabilize the heart in case of 'off-pump' surgery.
• The surgeon sutures cannulae into the heart and instructs the perfusionist to start cardiopulmonary bypass (CPB) in  case of 'on-pump' surgery.
• There are two technical approaches once CPB is established.
• The aortic cross-clamp can be placed across the aorta by the surgeon and the perfusionist is instructed to deliver cardioplegia with a cooled potassium mixture to stop the heart and slow its metabolism. Bypasses can also be performed on beating state.
• One end of each vein graft will be sewn on to the coronary arteries beyond the obstruction and the other end will be attached to the aorta or one of its branches.
• The artery is severed for the internal thoracic artery and the proximal intact artery will be sewn to the LAD beyond the obstruction.
• The aortic cross clamp will be removed in order to restart the heart. The stabilizing devices are removed in case of off-pump surgery.
• The patient is rewarmed to a normal temperature and the heart and other pressures are normal to support coming off the bypass machine once the grafts are completed distally and proximally.
• The perfusionist will ensure that anesthesia is ventilating the patient, vacuum assist is off if used, and vocalizes each step in the weaning process to the surgeon and anesthesia.
• The effects of heparin can be reversed by giving Protamine.
• Blood can be drained from around the heart and lungs by placing chest tubes in the mediastinal and pleural space.
• The sternum is wired together and the incisions will be closed.

Risks of Coronary Artery Bypass Surgery:

• An irregular heartbeat or a wound infection are usual risk associated with the surgery which is relatively minor and treatable.
• A risk of serious complications, such as a stroke or heart attack can also occur because of CABG.

Recovery from Coronary Artery Bypass Surgery:

• You will generally need to spend a day or more in the intensive care unit (ICU) and several days in a progressive care unit after your heart valve surgery.
• The duration of stay in the ICU and hospital will depend on your condition and surgery.
• Fluids and medications will be given through intravenous (IV) lines.
• Urine from your bladder and fluid and blood from your chest can be drained by other tubes.
• Oxygen can be given through a mask or nasal prongs in your nose.
• Your condition will be monitored and the signs of infection in your incision sites will be watched by your treatment team.
• The pain you have after surgery can be managed by your treatment team.
• A follow-up appointment will be there, typically about 6 to 8 weeks after your operation.
• Probably you will be able to return to most of your normal activities after about 6 weeks.