实时心肌造影结合斑点追踪技术评价不同顿抑状态犬心肌微循环与收缩功能变化

Research on characteristics of left ventricular microcirculation perfusion and systolic function in different conditions of stunned myocardium by real-time myocardial contrast echocardiography and speckle tracking imaging

目的:应用实时心肌造影技术(RT-MCE)和斑点追踪技术(STI),研究不同顿抑状态心肌的收缩功能和微循环的变化及相互关系,从影像可视化角度探讨顿抑心肌的生物学特征。方法:制作冠状动脉左前降支阻断后再灌注犬心肌顿抑模型,分为短顿抑组(阻断15min)、长顿抑组(阻断45min)和假手术组(不阻断),分别于阻断前、再灌注即刻、再灌注10、30、60、90、120min进行MCE和STI检查。实验结束后,心肌标本行透射电镜检查。结果:再灌注即刻,长顿抑组和短顿抑组缺血心肌的径向应变和A·β均低于基础状态及假手术组,差异具有统计学意义(P<0.01);随再灌注时间的延长,长顿抑组和短顿抑组缺血心肌A·β值较再灌注即刻时增高;至再灌注后30min,径向应变峰值进一步降低,再灌注60、90、120min,径向应变峰值有所恢复。再灌注120min时缺血心肌A·β值和径向应变峰值仍低于基础状态和假手术组。缺血心肌血流量(Y)与径向应变(X)呈线性关系,可拟合直线方程,其回归方程与相关系数为Y=0.443+49.64 X,r=0.80,R2=0.64,P=0.031(长顿抑组);Y=-2.184+65.88 X,r=0.78,R2=0.60,P=0.039(短顿抑组)。结论:STI能够反映心肌微循环血流情况。

Objective： To study the changes of left ventricular microeireulation perfusion and systolic function of stunned myocardium in dogs as well as the relationship between them by real-time myocardial contrast echocardiography （RT-MCE） and two-dimensional speckle tracking imaging（STI） in order to explore biological characteristics of stunned myocardium by im- aging methods. Methods： Open-chest beagle dogs were divided into 3 groups： short time stunned group, long time stunnedgroup and sham operation group. The acute myocardium ischemia was induced by ligating left anterior descending coronary ar- tery for 15 min （short time stunned group） or 45 min （long time stunned group）, followed by 120 min of reperfusion treat- ment, MCE and STI were performed before ischemia treatment, 15 min or 45 min after ischemia, as well as 10 min, 30 min, 60 rain, 90 min, 120 min after reperfusion. The myocardium was examined by transmission electron microscopy. Results： Compared with baseline data and data of sham operation group, the peak systolic radial （RS） and myocardial blood flow （A ·β） of Ischemic segments in long time stunned group and short time stunned group decreased significantly. A· β was progres- sively improved with reperfusion going. RS further decreased with reperfusion time going until 30 min after reperfusion, subse- quently progressively improved. But A·βand RS did not reach the pre-ligation level at 120 min of reperfusion. There were lin- ear relationship between the myocardial blood flow （A ·β） and peak systolic radial （RS）, the correlation coefficient with re- gression equation was Y=0. 443-1-49.64X,r=0.80,R^2 =0.64, P=0. 031（long time stunned group） ; Y= -2. 184＋65.88X,r = 0.78,R^2 =0. 60, P = 0. 039 （short time stunned group）. Conclusions： Microcirculation perfusion of stunned myocardium could be detected by STI. Based on MCE and SIT, dynamic biological characteristics of stunned myocardium could be detected reliably.