Experimental Study: Left Ventricular Segmental Function Evaluated By MCE,VVI,SRI And The Mechanism Of ROS And Cell Apoptosis In Acute Myocardial Ischemia Reperfusion

Coronary heart disease is the leading cause of death worldwide,and about 3.8 million men and 3.4 million women die of the disease each year.After an acute myocardial infarction,early and successful myocardial reperfusion with the use of thrombolytic therapy or primary percutaneous coronary intervention(PCI)is the most effective strategy for reducing the size of a myocardial infarct and improving the clinical outcome.The process of restoring blood flow to the ischemic myocardium,however,can induce injury(MIRI).It will lead to cardiac function decrease and apoptosis in clinical.How to prevent damage induced by ischemia -reperfusion and reduce the cell loss is the main target of clinical cure.Myocardial globe and regional ventricular function using echocardiography in IRI is the topic of clinical study.With the development of image technique,they are become new methods by Strain rate imaging(SRI),Velocity vector imaging(VVI) and Myocardial contrast echocardiography(MCE).May be they will provide credibility and accurate basis of diagnosis and evaluation in MIRI.At present,the mechanism of MIRI is also become the focus of recent study, However it remains unclear and has much controversy,It maybe correlate with ROS and apopotosis.Researching the relative mechanism clearly is very important to provide a new theory and basis for clinical prevention and therapy of myocardial ischemia and reperfusion. The objective of this study is to observe the regional myocardial function in acute ischemia-reperfusion model using SRI,VVI and MCE,and to study the change of ROS,Bcl-2,Bax,Bax/Bcl-2,Caspase and the apopotosis rate on the MIRI, additionally,the relationship between VVI and SRI on systolic peak strain rate,the relationship between myocardium cell apoptosis induced by Ischemia-reperfusion and the systolic peak strain rate by SRI was analyzed respectively too,in order to provide a new theory and basis for clinical diagnosis and evaluation,and also to inhibit the ischemia-reperfusion injury,improve the curative effect.The models with MIRI by occlusion of left coronary artery(LCA)followed release of LCA with a tie induced myocardial injury were made in dogs in vivo.The present study was divided into two parts:Part 1.Result1 TDI show the systolic peak velocity(V_SYS),strain(S_SYS)and strain rate(SR_SYS) of the mid left ventricular anterior and septal were significant decreased in ischemia group(IS)than in control group(Con)respectively(P＜0.01),and they were significant decreased in ischemia-reperfusion group(IR)than in ischemia group respectively(P＜0.01).2 VVI show the systolic peak velocity(V'_SYS),strain(S'_SYS)and strain rate (S'R_SYS)of the mid left ventricular anterior and septal were significant decreased in IS group than in Con group respectively(P＜0.01),and they were significant decreased in IR group than in IS group respectively(P＜0.01).3 There was well correlation between VVI and SRI on the systolic peak strain rate of the mid left ventricular anterior of IR group(r=0.562,P＜0.05).4 MCE show the k,A·k of the mid left ventricular anterior and septal were significant decreased in IS group than in Con group respectively(P＜0.05),and they were significant decreased in IR group than in IS group respectively(P＜0.05). Part 2.RESULTS1 The content of cellular and plasma of ROS,IS group was increased compare with Con group(P＜0.05),IR group was great increased compare with Con group (P＜0.01),IR group was great increased compare with IS group(P＜0.01);The content of plasma of MDA,IS group was increased compare with Con group (P＜0.05),IR group was great increased compare with Con group(P＜0.01),IR group was great increased compare with IS group(P＜0.01);But the content of plasma of SOD,GSH-PX,IS group was decreased compare with Con group(P＜0.05),IR group was great decreased compare with Con group(P＜0.01),IR was great decreased compare with IS group(P＜0.01).2 Compared with IS group,IR group the activation of Bax protein and Caspse protein expression were high(P＜0.01),the Bcl-2 protein expression is low(P＜0.01), and the Bax/Bcl-2 ratio was higher than IS group(P＜0.01).3 PI and AnnexinV/PI methods of flow cytometry(FCM)to detect the of cardiomyocyte apoptotic rate,the cardiomyocyte apoptotic rate in IS group was higher than Con group(P＜0.05),IR group was distinctly higher than Con group and IS group(P＜0.01).4 The SRsys detected by SRI was well correlated with the cardiomyocyte apoptotic rate detected by AnnexinV/PI in IR group(r=0.679,P＜0.05).Conclusion:1 They were feasible and accurate to diagnosis and evaluate the change of ischemia myocardial regional function by SRI,VVI and MCE.There was well correlation between VVI and SRI,VVI must be a available complementarity of SRI,VVI will have application in ischemia myocardial disease widely in the future.2 The increasing of ROS,the activation of Caspase-3,Bcl-2,Bax and Bax/Bcl-2 ratio maybe the mechanism of heart function descent resulting from myocardial apoptosis after myocardial ischemia-reperfusion.3 The increasing of the numbers of apoptsis may contribute to cardiac dysfunction,SRsys was well correlated with the cardiomyocyte apoptotic rate in IR group.