心肌声学造影界定急性心肌缺血面积的实验研究

Study of defining the area of the acute ischemical myocardium by myocardial contrast echocardiography

目的应用声学造影剂确定急性缺血心肌的临界点,探讨对心肌缺血面积的估测作用。方法选择健康杂种犬12只,建立开胸犬急性心肌缺血动物模型,经静脉注射声诺维造影剂并进行心肌声学造影(MCE)检查。在左心室心尖长轴二腔心切面,应用MCE的彩色M型曲线技术检测急性缺血心肌分别在前壁和下壁的临界点,以此为界在二维图像上描计出声诺维造影剂灌注缺损面积。启动Q-analysis软件,在左心室心尖长轴二腔心切面,将取样点置于心肌缺血区、临界区及正常心肌组织区,动态追踪此感兴趣区,选择每一心动周期舒张末期图像纳入分析,软件自动生成灌注强度曲线并拟合函数:Y=A(1-eβ2t)+C,得出曲线峰值强度(A),曲线斜率(β)和灌注量(A.β),每个区域的参数均取3次测量的平均值。通过计算局部组织蓄积的最大微泡数量(A)和造影剂在局部充填的速度(β)测定心肌相对血流量,并作为心肌血流灌注定量判断标准。结果 MCE所测定的左心室心肌缺血面积与美蓝染色后缺血面积实际参数高度一致(r=0.93,P=0.01)。回顾分析各个感兴趣点的定量指标,心肌正常灌注区的峰值强度(A)、曲线斜率(β)显著高于缺血区。缺血心肌区灌注量(A.β)较正常心肌区降低约70%,与心肌正常灌注区之间差异有统计学意义(P<0.05)。临界区灌注量(A.β)较正常心肌区降低约50%,与心肌正常灌注区之间差异有统计学意义(P<0.05)。结论 MCE可用于心肌缺血面积的估测,测定心肌缺血范围,确定心肌缺血的临界点。

Objective To determine the cut-off point and assess ischemic myocardium area in acute ischemic myocardium by MCE.Methods Eleven Open chest dogs were performed by MCE after ten minutes of left anterior descending coronary artery(LAD)occlusion for acute ischemia.M-mode of MCE defined the cut-off value of ischemic myocardium,and marked in anterior and inferior in images,respectively.Ischemic area was curved and compared with pathologic result.Start Q-analysis software,the long axis of the left ventricular apical two chamber view,the sampling point at the myocardial ischemic area,critical areas and normal myocardial tissue area,dynamic tracking the ROI,select end-diastolic images of each cardiac cycle included in the analysis,the software automatically generated perfusion intensity curve and the fitting function:Y=A(1-eβ2t)+C,reached peak intensity curve(A),slope(β)and perfusion(A·β),each region parameters are the average from 3 measurements.Local tissue accumulation by calculating the maximum number of microbubbles(A)and contrast agent filling in the local speed(β)determined the relative myocardial blood flow and myocardial perfusion as a quantitative criterion.Results There was correlation between Meis blue dye area and MCE ischemic area(r=0.93,P=0.01).The images of MCE ous area were significantly different versus the normal area.Retrospective were analyzed quantitatively from microbubble replenishment curves for myocardial perfusion.The A,β and A·β in the ischemic and suspicianalysis of quantitative indicators of each point of interest,myocardial perfusion areas of the peak intensity of the normal(A),slope(β)was significantly higher than the ischemic area.Ischemic area perfusion(A·β)lower than normal cardiac area of about 70%,and myocardial perfusion significantly between areas(P<0.05).Critical region perfusion(A·β)lower than normal by about 50% of myocardial area,and myocardial perfusion significantly between areas(P<0.05).Conclusions MCE can be used for estimating the ischemic area,mearsuring the range and determining the critical point of ischemic myocardium.