Coronary Artery Bypass Surgery (CABG)

Coronary Artery Bypass Surgery (CABG) introduction, purposes, indication, contraindication and procedure.

1. CORONARY ARTERY BYPASS GRAFT (CABG) Prepared by: PRABITA SHRESTHA

2. INTRODUCTION: Coronary artery bypass surgery , also known as  coronary artery bypass graft   surgery , and colloquially  heart bypass or   bypass surgery , is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease.  Arteries  or veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass atherosclerotic   narrowings  and improve the blood supply to the  myocardium.

3. INTRODUCTION: Coronary artery bypass graft surgery is a surgical 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 leg, arm, or chest

4. PURPOSE Coronary artery bypass graft surgery is performed to restore blood flow to the heart. This relieves chest pain and ischemia, improves the patient's quality of life, and, in some cases, prolongs the patient's life. The goals of the procedure are to relieve symptoms of coronary artery disease, enable the patient to resume a normal lifestyle, and to lower the risk of a heart attack or other heart problems.

5. INDICATION Left main coronary artery stenosis of 50% or greater Proximal vessel disease Multivessel disease and decreased left ventricular function. Chronic stable angina that is life style limiting and unresponsive to medical therapy or PTCA and stenting .

6. CONTRAINDICATION Small coronary arteries distal to the stenosis . Severe aortic stenosis . Severe left ventricular failure with co-existing pulmonary,renal,carotid,and peripheral vascular disease .

7. PROCEDURE: The patient is brought to the operating room and moved on to the operating table. An  anaesthetist  places a variety of intravenous lines and injects a painkilling agent followed within minutes by an induction agent ( usually propofol ) to render the patient unconscious. An  endotracheal tube is inserted and secured by the anaesthetist and mechanical ventilation is started. General anaesthesia is maintained by a continuous very slow injection of  Propofol .

8. The chest is opened via a median sternotomy  and the heart is examined by the surgeon. The bypass grafts are harvested – frequent conduits are the internal thoracic arteries, radial arteries and saphenous veins. When harvesting is done, the patient is given heparin to prevent the blood from clotting. In the case of "off-pump" surgery, the surgeon places devices to stabilize the heart.

9. If the case is "on-pump", the surgeon sutures  cannulae  into the heart and instructs the  perfusionist  to start cardiopulmonary bypass(CPB). Once CPB is established, the surgeon places the aortic cross-clamp across the aorta and instructs the perfusionist to deliver  cardioplegia  (a special potassium-mixture, cooled) to stop the heart and slow its metabolism. Usually the patient's machine-circulated blood is cooled to around 84 °F.

10. 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; or in "off-pump" surgery, the stabilizing devices are removed. In cases where the aorta is partially occluded by a C-shaped clamp, the heart is restarted and suturing of the grafts to the aorta is done in this partially occluded section of the aorta while the heart is beating.

11. Protamine  is given to reverse the effects of heparin. Chest tubes are placed in the mediastinal and pleural space to drain blood from around the heart and lungs. The sternum is wired together and the incisions are sutured closed. The patient is moved to the intensive care unit (ICU) to recover.

12. Nurses in the ICU focus on recovering the patient by monitoring blood pressure, urine output and respiratory status as the patient is monitored for bleeding through the chest tubes. If there is chest tube clogging, complications such as cardiac tamponade ,  pneumothorax  or death can ensue. Thus nurses closely monitor the chest tubes and under take methods to prevent clogging so bleeding can be monitored and complications can be prevented. After awakening and stabilizing in the ICU (approximately one day), the person is transferred to the cardiac surgery ward until ready to go home (approximately four days).

13. COMPLICATION Death MI STROKE Wound infection Acute kidney failure Blood clots Postoperative bleeding Multiple organ system failure

14. R eferences Lippincot , Manual of Nursing Practice , 8 th edition , Page no. 371 to 372 Brunner and Suddarth , Medical and Surgical Nursing ,10 th edition , Page no . 715 to 720 Black hawks , Medical and Surgical Nursing , 7 th edition , Page no . 1641 to 1642 en.wikipedia.org/wiki/ Coronary_artery_bypass_surgery