异氟烷预处理对心脏换瓣术患者血MMP 9的影响及其对心肌的保护作用

目的：观察异氟烷预处理对体外循环（cardiopulmonary bypass,CPB）心脏换瓣术患者围术期血浆基质金属蛋白酶 9（matrix metalloproteinase 9，MMP 9）及心肌超微结构的影响，评价其对心肌的保护作用。方法：择期CPB下行瓣膜置换术的心脏瓣膜病患者30例，随机分为异氟烷预处理组（异氟烷组，n＝15）和对照组（n＝15），异氟烷组在麻醉诱导后CPB前吸入1.1%~1.2%(呼气末浓度)的异氟烷30 min，洗脱15 min，对照组不吸入异氟烷，其余用药两组无区别。分别于切皮前(T0),主动脉开放30 min（T1），6 h（T2），12 h（T3）及24 h（T4）经桡动脉取血测血浆MMP 9浓度，分别于CPB前后取部分右心耳组织电镜下观察超微结构。结果：与T0比较，对照组血浆MMP 9浓度在T1-T3显著增加，异氟烷组血浆MMP 9浓度只在T1显著升高（P<0.01）；与对照组比较，异氟烷组血浆MMP 9浓度在T2显著降低（P<0.01）,在T1-T3各时点与T0的差值均显著降低（P<0.01）。电镜下可见对照组CPB后心肌细胞损伤比异氟烷组严重。结论：异氟烷预处理能显著抑制心脏换瓣术患者CPB后MMP 9的分泌增多，这可能是其对心脏换瓣术患者心肌保护的机制之一。

Isoflurane preconditioning decreases the plasma concentrationof matrix metalloproteinase 9 and protects myocardium againstcardiopulmonary bypass in cardiac valve replacement

ObjectiveTo explore the effect of isoflurane preconditioning on the plasma concentration of matrix metalloproteinase (MMP) 9 and myocardial ultramicrostructure in patients undergoing cardiac valve replacement. MethodsThirty patients undergoing elective cardiac valve replacement with cardiopulmonary bypass(CPB) were randomly assigned to a control group （n＝15） and an isoflurane group （n＝15）. In the isoflurane group, isoflurane of 1.0 minimum alveolar concentration end tidal(1.1%~1.2%) was administered for 30 min followed by a 15 min washout period before the CPB. The control group did not inhale isofurane, and there was no difference in the other drugs in the 2 groups. Blood samples for MMP 9 were obtained before incision(T0) and at 30 min (T1)，6 h (T2)，12 h (T3), and 24 h (T4) after the reperfusion. Right atrial biopsies were collected before and after the CPB to observe the myocardial ultramicrostructure. ResultsCompared with T0, the mean MMP 9 level significantly increased at T1, T2 and T3 in the control group(P<0.01), while the MMP 9 level only at T1 significantly increased in the isoflurane group (P<0.01). The mean MMP 9 level was significantly reduced in the isoflurane group at T2 compared with each time point in the control group. The difference in MMP 9 levels between T1, T2, T3 and T0 was significantly lower in the isoflurane group than that in the control group (P<0.01). The ultramicrostructure injury of myocardium under electron microscope in the control group was worse than that in the isoflurane group. ConclusionThe plasma concentration of MMP 9 is inhibited by isoflurane preconditioning in patients undergoing cardiac valve replacement after CPB, which might be part of its protective mechanism against myocardium injury after CPB.