右美托咪定预处理对瓣膜置换术患者缺血后心肌的影响

目的 评价右美托咪定预处理对体外循环下二尖瓣置换术患者心肌缺血再灌注损伤的影响.方法 择期行心脏二尖瓣置换术患者60例,随机分为两组:对照组和右美托咪定组(DEX组),分别在主动脉阻断前30 min给予0.9%生理盐水10 ml、0.6 mg/kg右美托咪定10 ml,微量泵注射10 min完成.收集麻醉诱导前(H0)、气管插管后(H1)、给药前(H2)、给药后(H3)、体外循环(CPB)后即刻(H4)、CPB后30 min(H5)、CPB后1 h(H6)、CPB后2 h(H7)患者的平均动脉压(MAP)、心率(HR).在麻醉诱导前(T0)、主动脉开放2 h(T1)、4 h(T2)、8 h(T3)、12 h(T4)抽取桡动脉血样2 ml.测定心肌肌钙蛋白I(cTnI)、肌酸激酶同工酶(CK-MB)、丙二醛(MDA)浓度和超氧化物歧化酶(SOD)活性.结果 与H0相比,对照组在H5、H6 MAP明显降低,HR明显升高(P<0.01),DEX组无明显变化;与对照组相比,T1~T4时DEX组患者cTnI、CK-MB和血清MDA明显降低,SOD明显升高(P<0.01).结论 右美托咪定预处理可减轻CPB下心脏瓣膜置换术患者心肌缺血再灌注损伤,其机制与抑制氧化应激反应有关.

Effect of dexmedetomidine preconditioning on ischemic myocardium in patients undergoing heart valve replacement surgery

Objective To investigate the effect of dexmedetomidine preconditioning on myocardial ischemia-reperfusion injury(IRI) in patients undergoing mitral valve replacement under cardiopulmonary bypass(CPB).Methods Sixty patients,aged 18~65 years,scheduled for cardiac valve replacement under CPB were randomly divided into 2 groups(n=30 each).DEX group:0.6 mg/kg dexmedetomidine was infused over 10 min via radial artery 30 min before aortic clamping;CON group:0.9% normal saline was infused instead.Blood sample was taken from the radial artery immediately before induction of anesthesia(T0) and at 2,4,8,12 h after aortic unclamping(T1~T4) for determination of plasma concentration of cardiac troponin(cTnI),malondialdehyde(MDA),creatine kinase isoenzyme-MB(CK-MB) and superoxide dismutase(SOD).Hemodynamic data were recorded before induction of anesthesia(H1),after endotracheal intubation(H2),before and after study drug(or SP) loading dose(H3,H4),and at 0 min(H5),30 min(H6),1 h(H7),2 h(H8) after CPB.Hemodynamic data included heart rate(HR),mean arterial pressure(MAP).The duration of CPB,time of aortic clamping,extubation time,duration of stay in ICU and myocardial contractility score and volume of drainage at 12 h after the operation were recorded.The resto-ration of spontaneous heart beat and adverse cardiovascular events were observed.Results Compared to H0,MAP of H5,H6 in CON group were significantly lower (P<0.01),HR of H5,H6 in CON group were significantly higher(P<0.01);Compared to CON groups,MAP of H5,H6 in DEX group were significantly higher(P<0.01),HR of H5,H6 in DEX group were significantly lower(P<0.01);Compared to T0,the plasma cTnI and MDA concentration and CK-MB were significantly higher at T1~T4 in two groups while the plasma SOD was significantly lower(P<0.01).Compared to CON group,the plasma cTnI and MDA concentration and CK-MB were significantly higher while the plasma SOD was significantly lower(P<0.01).Exudation time and duration of stay in ICU were significantly shorter.The myocardial contractility score at 12 h after the operation and incidence of adverse cardiovascular events were significantly lower(P<0.05).Conclusion Dexmedetomidine preconditioning can ameliorate myocardial I/R injury in patients undergoing cardiac valve replacement under CPB,and the mechanism is related to inhibition of lipid perexidation.