实时心肌超声造影评价急性心肌缺血的实验研究

目的 评价实时心肌超声造影(MCE)识别大鼠急性心肌梗死心梗范围的准确性,及定量分析缺血心肌血流灌注的特性.方法 雄性Wistar大鼠20只,结扎冠脉左前降支,制备急性心肌梗死(AMI)模型.分别采集基础状态及梗死状态下的RT-MCE 图像.分别在缺血区和灌注正常的心肌取感兴趣区,得出造影成像的强度-时间曲线,读出峰值视频强度PI、A、β、A·β值.结果 MCE显示梗死区灌注充盈缺损,灌注缺损区面积(30.67±6.42)%与病理染色证实的心梗面积相关性好(r=0.87).心梗区PI较正常灌注区低 (5.45±3.07) dB vs (23.03±5.27) dB (P<0.05).灌注缺损区的A、β、A·β值等均与正常心肌MCE灌注参数值间存在显著差异(P<0.05).结论 MCE能无创地准确估测梗死面积.梗死区MCE血流灌注指标显著降低.

Quantifying Myocardial Perfusion with Contrast Echocardiography after Acute Myocardial Infarction: an Experimental Study

Objective To investigate the diagnostic value and the myocardial coronary microcirculation flow infusion characteristics of real-time myocardial contrast echocardiography (RT-MCE) after acute myocardial infarction(AMI).Methods Coronary complete occlusion was produced in 20 mice by constricting left anterior descending coronary artery (LAD).RT-MCE was performed at baseline and after AMI.Regions of interest (ROI)) were placed individually within hypoperfusion and normal perfusion.Myocardium and myocardial signal intensity versus real-time frame curves were made and fitted to an exponential function:Y=A(1-e~(-βt)),to obtain values of A,β and A·β.Results Coronary occlusion induced coronary hypoperfusion and reduced coronary microvascular volume.The nonperfused myocardial area (30.67±6.42)%,as measured by the contrast perfusion defect,was significantly correlated with the area of infracted myocardium by Masson dye (r=0.87).PI from hypoperfusion segments decreased than that from normal perfusion myocardium (5.45±3.07) dB vs (23.03 ±5.27) dB(P<0.05).A,β and A·β in hypoperfusion segments were decreased than those in normal perfusion myocardium(P<0.05).Conclusions RT-MCE can accurately detect and measure the extent of the myocardial area at risk,in a minimally invasive manner.Significantly decreased myocardial blood flow and reperfusion velocity were related to microvascular abnormalities induced by AMI.