Myocardial Protection Of Adenosine And L-carnitine Comedication Pretreatment On Type 2 Diabetic Patients Undergoing Coronary Artery Bypass Graft Without Extracorporeal Circulation

Objective To investigate the protective effect of pretreatment with adenosine and L-carnitine comedication on myocardium in type 2 diabetes mellitus patients undergoing off-pump coronary artery bypass grafting. Methods Forty three-vessel coronary artery disease patients with type 2 diabetes mellitus, cardiac functionⅡorⅢgrade, aged 45-70 yr, weighing 60-85kg, scheduled for off-pump coronary artery bypass grafting, were randomly divided into 2 groups (n=20 each). A group (comedication with adenosine and L-carnitine): L-carnitine injectio 0.1g/kg dissolved in normal saline was infused intravenously once a day for 5 days before operation. After anesthesia induction, L-carnitine 0.1g/kg dissolved in normal saline 100ml was infused intravenously at a rate of 35ml/h via peripheral vein and adenosine 2.5mg/kg dissolved in normal saline 50ml initially was infused 30μg/kg/min via the central vein catheter before incision and increased 5μg/kg/min every 10 minutes on Syringe pump until anastomosing LAD. C group (control):neither L-carnitine nor adenosine except equal volume of saline was used in the perioperative period. GIK 500ml (KCl2.0g, Regular Insulin 8U,5% Glucose500ml, Potassium Magnesium Aspartate 100ml) was infused at the rate of 150ml/h immediately after the beginning of induction of anesthesia to the patients in the both group. Blood glucose was surveyed every 30 min and regular insulin was infused via the central vein catheter on Syringe pump until the patient blood glucose was not more than 7mmol/L in both groups during the operation. The blood sample were taken from vein at 8 time points (anesthesia induction (T0),30min (T1) after aortic unclamping and 3h (T2),12h (T3),24h (T4),48h (T5),72h (T6) and 7d (T7) post-operation) to measure the plasma concentration of the creatine kinase(CK-MB), troponin I(cTNI), superoxide dismutase (SOD),malondialdehyde(MDA). The other observation parameters such as extubation time, LVEF improvement, peri-operative myocardial injury were scored. Result LVEF of A group were significantly improved compared with C groups at 7d after operation (63.23±5.74 vs 54.74±8.35, P＜0.05). By contrast, insulin demand in group A was significantly reduced as compared with group C (0.4±1.27U vs 5.3±2.74U, P＜0.05). Compared with To, plasma MDA concentrations at T1-2, cTnl and CK-MB activities at T1-6 were significantly increased (P< 0.05或P<0.01); SOD activity at T1,2 was significantly decreased in the both groups (P< 0.05 or P<0.01). Plasma MDA concentrations at T1,2, cTnl and CK-MB activities at T1-6 and required dosage of dopamine were significantly lower (P<0.05 or P<0.01) and SOD activity at T1,2 were significantly higher in A group than in C group(P<0.05 or P<0.01). Less patients needed adrenaline medication and significantly lesser dosage of dopamine was required in the perioperative period in A group as compared with C group (P＜0.05).Conclusion adenosine and L-carnitine comedication pretreatment on off-pump coronary artery surgery can protect myocardium in patients with type 2 diabetes mellitus.