左卡尼汀预处理对体外循环下先天性心脏病患儿的心肌保护效果

Myocardial Protective Effect of Levocarnitine Preconditioning During Cardiopulmonary Bypass in Infants with Congenital Heart Disease

目的：探讨左卡尼汀预处理对体外循环（CPB）下先天性心脏病（CHD）患儿的心肌保护效果。方法：择期CPB下行室间隔缺损修补术的患儿60例，年龄5～18个月，采用随机数表法分为对照组（C组）和左卡尼汀组（L组）各30例。L组于术前7d开始静脉滴注左卡尼汀20mg／（kg·d），疗程7d；C组给予等量生理盐水。于麻醉诱导后5min（T0，基础状态）、主动脉开放后30min（T1）、术后6h（T2）、12h（T3）和24h（T4）取颈静脉血测定心肌肌钙蛋白I（cTnI）浓度和肌酸激酶同工酶（CK—MB）活性。于主动脉阻断前和主动脉开放后30min取右心耳心肌组织，电镜下观察心肌超微结构，并行心肌细胞线粒体损伤评分。记录术后血管活性药物使用情况、带管时间及ICU停留时间。结果：与C组比较，L组T1～T4时点血浆cTnI浓度和CK—MB活性降低（P〈0．01），主动脉开放后30min时心肌病理学损伤减轻，心肌细胞线粒体损伤评分降低（2．16±0．51 vs 3．13±0．59，P〈0．01），术后多巴胺和多巴酚丁胺用量减少（5．3±0．8 vs 7．7±0．9，4．3±0．7 vs 6．2±0．5，P〈0．01），带管时间和ICU停留时间比较差异无统计学意义（24±3 vs 22±3，66±11 vs 65±10，P〉0．05）。结论：左卡尼汀预处理可使CPB下CHD患儿心肌酶漏出减少，心肌细胞超微结构损害减轻，具有较好的心肌保护作用。

Objective： To investigate the myocardial protective effect of levocarnitine preconditioning during cardiopulmonary bypass （CPB） in infants with congenital heart disease （CHD）. Methods： Sixty infants aged 5 - 18 months undergoing repair of ventricular septal defect during CPB were randomly divided into two groups （n=30, each） ： a control group （group C） and a levocarnitine group （group L ）. The patients in group L were infused levocarnitine for seven days from operation beginning, with the dose of 20 mg/（ kg · d）. The patients in group C were given the same amount of 0.9% sodium chloride. Blood samples were taken from central vein at 5 rain after the induction of anesthesia （T0, baseline）, 30 min after release of the aortic cross-clamp （ T1 ） and at 6 h （ T2 ）, 12 h （T3 ） and 24 h （T4 ） after operation for determination of plasma cardiac troponin I （cTnI） concentration and creatine kinase-MB （CK-MB） activity. Myocardial specimens were obtained from right auricle before aortic cross-clamping and at 30 min after release of aortic cross-clamp for ultrastructure examination ; the severity of mitochondria injury was assessment and scored. The dosage of vasoactive drugs, extubation time and the length of intensive care unit （ICU） stay were observed. Results： The plasma mass concentrations of cTnI and activity of CK-MB were significantly lower at all time points after release of the aortic cross-clamp in group L than those in group C （P〈0.01）. Mitochondrial injury score was significantly lower at 30 min after release of aortic cross-clamp in group L than that in group C （2.16 ±0.51 vs 3.13 ±0.59, P〈0.01 ）. The doses of dopamine and dobutamine were significantly lower after operation in group L than those in group C （5.3±0.8 vs 7.7±0.9, 4.3±0.7 vs 6.2±0.5, P〈0.01 ）. The extubation time and length of ICU stay had no significant differences during postoperative period in group L and group C （24±3 vs 22±3, 66v11 vs 65±10, P〉0. 05 ）. Conclusions： Levocarnitine preconditioning can reduce the levels of cTnI and the activity of CK-MB, and the damage of myocardial ultrastructure. Therefore, it may effectively protect myocardium during cardiopulmonary bypass in infants with CHD.