The Clinical And Experimental Study Of Dexmedetomidine Postconditioning Against Myocardial Ischemia-reperfusion Injury

ObjectiveThis study was aimed to compare the effect of postconditioning withdexmedetomindine and midazolam on myocardial ischemia-reperfusion injury and explorewhether the postconditioning using dexmedetomindine has myocardial protective effects. Itwill provide theoretical basis for a safe and effective sedation in patients with acutemyocardial infarction.MethodsThis study was composed of the following two parts: animal experiments and clinicaltrials. Part one: Effect of postconditioning with dexmedetomidine and midazolam on acutemyocardial ischemia-reperfusion injury in rats.36male SD rats were randomly dividedinto6groups (each group n=6): control group (C), ischemia-reperfusion group (I/R),dexmedetomidine infusion after ischemia (D1), dexmedetomidine infusion afterreperfusion (D2), midazolam infusion after ischemia (M1), midazolam infusion afterreperfusion (M2). The rats in group C and I/R were infused the equivalence volume ofsaline. The model of rat’s myocardial ischemia-reperfusion was performed. All groupswhich ligation of the left anterior descending coronary artery were subjected to30min ofischemia followed by90min of reperfusion except group C. The level of plasma LDH andCK were measured and recorded before ligation and at90min of reperfusion. Infarct sizewas determined with TTC staining at90min of reperfusion. Part two:60patientsundergoing emergency PCI with acute myocardial infarction were selected and randomlydivided into Group D (dexmedetomidine use, n=30) and Group M (midazolam use, n=30).Preoperatively,1μg/kg of dexmedetomidine were infused, finished in following l0min inGroup D,0.05mg/kg of midazolam in Group M with the same infusion time.Intro-operatively,0.2-1.4μg·kg-1h-1of dexmedetomidine were given for maintenance inGroup D and0.02-0.1μg·kg-1h-1of midazolam in Group M. The values of the heart rate (HR), blood pressure and pulse oxygen saturation (SPO2) of the patient were recorded inpreoperative, end of surgery, finished bolus and postoperative1day. Also the levels ofplasma myocardial enzyme spectrum and cardiac troponin were measured in preoperative,postoperative3days. Echocardiography was also performed in preoperative andpostoperative3days; the values of EF were recorded. The incidences of complication, thelength of ICU stay and hospitalization stay were also collected.ResultsPart one: There was no significant difference in the levels of LDH and CK amonggroups before ligation (P>0.05). Compared with group C, there was a significant increasein the levels of LDH and CK and infarct size among the five groups at the90min ofreperfusion (P<0.05); compared with group I/R, there was a significant decrease in thelevels of LDH and CK and infarct size in group D1(P<0.05).Part two:(1) There was no significant difference in the value of HR、SPO2and bloodpressure between two groups in preoperative (P>0.05). Compared with Group M, the valueof HR reduced sharply at the time of bolus、end of surgery and postoperative1day inGroup D. The value of SBP also reduced sharply at the end of bolus infusion and surgeryin Group D (P<0.05).(2) There was no significant difference in the value of HR,myocardial enzyme spectrum, troponin I and EF in preoperative between two groups(P>0.05). Compared with Group M, there was a significant decrease of heart rate,myocardial enzyme spectrum and troponin I in Group D, but the echocardiographic EFvalue increased (P<0.05).(3) There was no significant difference in the incidences ofcomplication, but the length of ICU stay and hospitalization stay in Group D were moreshorter than in Group M (P<0.05).ConclusionPostconditioning with Dexmedetomidine has the protective effect on myocardiumassaulted by ischemia-reperfusion in vivo. It can provide a safe and effective sedation inpatients with acute myocardial infarction.