Combined Use Of Cardioplegia And L-carnitine Attenuates Myocardial Ischemia-reperfusion Injury In Patients Undergoing Cardiopulmonary Bypass

Objective To evaluate the protective effects of cardioplegia andL-carnitine on myocardial ischemia-reperfusion (I/R) injury in patientsundergoing cardiopulmonary bypass (CPB).Methods Sixty patients undergoing elective cardiac valve replacementin the Department of cardiac surgery, First Affiliated Hospital of GuangxiMedical University, were evenly assigned into3groups (n=20each): group A(infusion with St. Thomas’ II cold crystalloid cardioplegia and6g/L L-carnitineintraoperatively), group B (infusion with St. Thomas’ II cold crystalloidcardioplegia and12g/L L-carnitine intraoperatively), and group C (infusiononly with St. Thomas’ II cold crystalloid cardioplegia). Immediately followingcross-clamping of the ascending aorta, the cardioplegia was infused into theaortic root to arrest the heart. After release of the aortic cross-clamping, cardiac recovery was assessed by the heart auto re-beat ratio, the post-reperfusionrhythm, and electric defibrillation use. Blood samples were collected from rightinternal jugular vein at5min after anesthesia (T0, baseline),30min afterrelease of aortic cross-clamping (T1), at6h (T2), and12h (T3) after operationfor measuring plasma cardiac troponin I (cTnI), malonaldehyde(MDA), creatinekinase-MB (CK-MB), and superoxide dismutase (SOD). Cardiac index (CI) andleft ventricular ejection fraction (LVEF) were determined at1daypreoperatively and7days postoperatively using color duplex ultrasonography.Results Compared with group C, a higher heart auto re-beat ratio,lowerarrhythmiaand electric defibrillation ratio were found in group A and B(P<0.05). Levels of cTnI, CK-MB, and MDA were significantly lower, but SODwas significantly higher in group A and B than those in group C at all timepoints (P<0.05). Compared with group C, CI and LVEF were significantlyincreased at7days after operation in group A and B (P<0.05). In addition, therealso a statistical difference between group A and B for all the above index, withsuperior effects using group B treatment(P<0.05).Conclusion L-carnitine can be used as a complementary drug forcardioplegia to attenuate myocardial I/R injury and recover left ventricularsystolic function in patients undergoing CPB. The protective effective ofL-carnitine presented a dose-dependent manner.