Evaluation Of Adenosine Preconditioning Protective Effects And Its Mechanism By Real-time Myocardial Contrast Echocardiography

ObjectiveAs the incidence of coronary heart disease is growing,acute myocardial infarction has become a major threat to human life.patients with coronary thrombolysis, emergency PTCA and coronary artery bypass grafting of the promotion, ischemia-reperfusion(IR) injury became a serious fatal pathophysiological changes after recovery of myocardial reperfusion.In addition,myocardial IR injury happened often during the anesthesia and surgery,such as a serious lack of ventilation,anesthesia accidents,respiratory and cardiac arrest,cardiac surgery.Therefore,prevention myocardial IR injury has became an important issue both at home and abroad in recent years.Real-time myocardial contrast echocardiography(rt-MCE) is a new method for myocardial microcirculation assessed.The purpose of this study is the application of rt-MCE techniques of adenosine preconditioning on the canine myocardial IR injury to find myocardial contractile function and myocardial microcirculation changes. Discussion on the protective and its mechanism of "adenosine preconditioning" of the canine myocardial IR injury.Methods1,Division of laboratory animalsSelection of 14 healthy dogs,weighing 12kg～16kg,male and female informal, were randomly divided into 2 groups(n=7) control group:ischemic 3h,reperfusion 1h, prior to ischemia,intravenous infusion of normal saline 30ml was given as a balance control;adenosine preconditioning groups:intravenous infusion of adenosine before ischemia 0.3mg/min,30min after drops in total of intravenous drug 30ml.and then repeat the experiment of control group.2,Experimental methods (1) Myocardial functionusing multi-channel recording and analysis of biological treatment systems for treating myocardial contractile function.(2)Rt-MCERt-MCE was performed in fundament condition,acute myocardial infarction model three hours after the coronary ligature and one hour's reperfusion respectively. SonoVue microbubbles were administered as a constant venous infusion,and rt-MCE was fitted to an exponential function:y=A(1-e-βt),where A reflected microvascular cross-sectional area(or myocardial blood volume),andβreflected mean myocardial microbubble velocity.The product of A·βrepresented myocardiol blood flow(MBF).(3) Evan's blue+TTC stainingAt the end of the experiment,all animals were killed by 30ml 10%Kcl,using Evan's blue+TTC staining measurements necrotic area(NA) and the dangerous area (RA),calculation the ratio of NA/RA.(4) Data AnalysisInformation to mean±standard deviation((?)±s) that SPSS 13.0 statistical software using a two-sample t test and analysis of variance,P＜0.05 for statistical significance.Results1.Myocardial functionTwo groups of dogs underwent 3h ischemia and 1h reperfusion peak left ventricular pressure(LVSP) and±dp/dtmax value in foundation status were decreased and improved after 1h reperfusion;In adenosine preconditioning group after 1h reperfusion,LVSP restore is better than the control group.compared with control group, at the time of 3h ischemia and 1h reperfusion,±dp/dtmax recovery rate are also better in adenosine preconditioning group.By the way,the incidence rate of arrhythmia in adenosine preconditioning group was reduced.2.Rt-MCEMyocardial biood flow in risk area and necrotic area are obviously decreased than basement conditions.The lowest myocardial blood flow was found in necrotic area. compared with control group,myocardial biood flow in risk area in adenosine preconditioning group was increased. 3.Evan's blue+TTC stainingDifferent extent of infarct size in subendocardiac muscle was observed in the two above groups,compared with control group,the ratio of NA/RA in adenosine preconditioning group was decreased.Conclusions1.Adenosine precondition could improve cardiac systolic function after IR injury.2.Adenosine precondition could also improve myocardium microcirculation,increasing myocardium perfusion at risk area,decreasing no-reflow area and infract area.3.Rt-MCE can be used to quantitative assessment the protection effects of adenosine precondition after IR injury.