Comparison Of Cerebral Injury In Patients With Coronary Artery Bypass Graft With And Without Cardiopulmonary Bypass

Backgrounds: Cerebral injury after cardiac surgery is still a major complication after cardiac surgery despite the improvement of the cardiopulmonary bypass(CPB). Recent studies show that the incidence of overt cerebral dysfunctions such as hemiplegia has reached 0.8%-5.2%.Subtle cerebral injury in 20%-60% of patients within a week, and Cognitive impairment persists in 25%-30% of patients 8 weeks later. During recent years, off-pump coronary artery bypass grafting(OPCAB) which can avoid the side-effect of CPB has developed rapidly .Although OPCAB has been accepted by more and more medical center, there are no prospective investigation in domestic to compare the cerebral injury in patients with coronary artery bypass grafting with and without cardiopulmonary bypass. SI00 protein which is highly specific for the brain, is an early marker of cerebral damage and helpful in cerebral injury detection, especially for sub-clinical brain injury such as cognitive dysfunction.Our purpose was to compare the difference of cerebral injury in patients of OPCAB and CCABG as indicated by changes in serum concentrations of S-100 protein. We also want to observe the relationship of cerebral injury and systemic inflammatory response syndrome(SIRS) by investigating the relationship between S100 protein and TNF- a and H-8.Materials and Methods: 40 consecutive Patients who first accepted CABG from October in 2002 to January in 2003 were separated into two groups:(1) OPCAB group n=20, and (2) CCABG group, n=20.Preoperationally, all patients accepted carotid artery multidoppler ultrasonography. Their ejection fraction(EF)>30%, and there were no carotid artery stenosis, no severe pulmonary, liver, renal dysfunction, no coagulopathy, no myocardial infarction(MI) a month before operation, and no nervous system disease such as transient ischemia attack(TIA), cerebral hemorrhage, cerebral infarction or cerebral trauma. Both groups were similar regarding age, sex, ejection fraction, and number of anastomoses. Anesthetic technique was standardized for all patients.Premedication comprised morphine, scopolamine.Anaesthesia was initiated with fentanyl(5-10 ug/kg ), muscle relaxation was achieved with pancuronium(0.1-0.2 ug/kg).Mechanical ventilation was initiated(tidal volume, 8-10 ml/kg; rate, 12-15/min)and anaesthesia was supported by inhalation 1% isoflurane.Operative monitoring was identical in all patients.OPCAB group underwent operation on the beating heart without CPB.For anastomoses we used the Medtronic Octopus III Retractor.CCABG group instituted CPB by means of ascending aortic canrmlation ( 20-22F ) and a 2-stage venous cannulation ( 38-42F ) via the right atrium.We used cold blood cardioplegia administered antegrade into the aortic root.Patients were not actively cooled, but drifted to a rectal temperature between 32-34℃. Blood sample were taken from internal jugular vein at 8 time points: 24 hours pre-operation, post-heparinization, aortic declamping, 2, 6, 12, 24, 48 hours afterthe cardiac surgery. S100 levels and TNF-α, IL-8 of both group were measured. We also evaluated perioperational state of nervous system by examining the patients'neuropsychological system. Results:There were no deaths or major neurologic complications in either group.S100 levels increased only slightly in the OPCAB group, whereas in CCABG group there was a sharp rise in S100 concentration during CPB, only returning to baseline 6 hours after the end of the operation. Peak S100 levels were 3 times higher in CCABG group than in OPCAB group ( 2.17μg/L versus 0.74μg/L, P<0.01 ) . S100 levels at 5 min after reperfusion were correlated with age and duration of CPB.Levels of TNF- a and IL-8 in group B increased obviously, reaching 9.49ng/ml and 1.05ng/ml respectively at 5 min after reperfusion.They continued to increase and reach Peak levels of 10.46ng/ml and 1.58ng/ml., P<0.01 ) .There was significant difference of Levels of TNF- a and IL-8 between OPCAB group and CCABG group ( P<0.01 ). S100 levels at 5 min after reperfusion had significant c...