斑点追踪技术评价犬急性心肌缺血及再灌注心内膜下心肌和心外膜下心肌径向应变

目的应用斑点追踪技术检测犬急性心肌缺血及再灌注不同时间点心内膜下心肌和心外膜下心肌的径向应变。方法选取20只健康成年杂种犬,结扎左冠状动脉第一对角支,分别对结扎前、结扎即刻、60、120和180min及再灌注即刻、60和120min基底水平、乳头肌水平和心尖水平心内膜下和心外膜下心肌的径向应变进行比较。结果在急性缺血过程中,基底水平心肌起代偿作用,其径向应变上升;乳头肌水平和心尖水平心肌下降明显,心尖水平心肌甚至出现反向运动。在急性缺血及再灌注过程中,心内膜下心肌对缺血更加敏感。再灌注后,乳头肌水平和心尖水平心内膜下和心外膜下心肌及跨壁的径向应变仍低于基础状态。结论斑点追踪技术可以评价犬局部及整体心脏功能,并判断急性心肌缺血的透壁程度。

Speckle tracking imaging in evaluation of radial strain of subendocardial and epicardial myocardium in canine acute myocardial ischemia and reperfusion

Objective To evaluate the radial strain function of subendocardial and epicardial myocardium in acute myocardial ischemia and reperfusion canine with speckle tracking imaging. Methods The first diagonal branch of left coronary artery of 20 adult healthy hybrid dogs were ligated. Radial strain of subendocardial and epicardial myocardium at basal, apical and papillary muscle level were compared by speckle tracking imaging before ligation, ligation immediately, 60,120, 180 min after ligation, reperfusion immediately, and 60, 120 min after reperfusion, respectively. Results Radial strain of basal level elevated by compensatory role in canine acute ischemic process. Radial strain of apical and papillary muscle level decreased obviously. Myocardial reverse movement was even found at apical level. In acute ischemia and reperfusion process, subendocardial myocardium was more sensitive to ischemia. After reperfusion, radial strain of subendocardial and epicardial myocardium at apical and papillary muscle level were still lower than that in basic status. Conclusion Speckle tracking imaging can objectively quantify regional and overall heart function and transmural extent of myocardial infarction in canine.