应用斑点追踪成像技术对急性心肌缺血及再灌注心内膜下心肌和心外膜下心肌旋转及扭转功能的研究

目的：本研究旨在应用斑点追踪成像（STI）技术通过测定心内、外膜下心肌、跨壁旋转及扭转角度等指标对急性心肌缺血及再灌注期间心脏功能进行评价。方法：对20只健康成年杂种犬结扎左冠状动脉第一对角支下方180 min并再灌注120 min，分别对结扎前、结扎即刻、结扎60 min、结扎120 min和结扎180 min及再灌注即刻、再灌注60 min和再灌注120 min基底水平和心尖水平的旋转及扭转指标进行比较。结果：①基底水平旋转的比较：随着缺血时间延长，跨壁角度逐渐减低。再灌注即刻，跨壁角度一过性增大。再灌注120 min，跨壁角度最低。②心尖水平旋转的比较：跨壁角度从结扎即刻开始下降，至结扎180 min达到最低值。再灌注即刻，跨壁角度快速上升。再灌注60 min、120 min缓慢上升。③扭转的比较：随着缺血时间的延长，跨壁扭转角度明显下降。结扎180 min跨壁扭转角度最低。再灌注即刻跨壁扭转角度快速恢复。结论：STI技术通过定量分析左室心内膜及心外膜下心肌局部和整体的旋转及扭转，可以判断心脏功能的变化。心内外膜下心肌旋转角度及跨壁角度、扭转角度及跨壁角度是评价急性心肌缺血及再灌注后室壁运动及心脏功能的有效手段。

Research on rotation and torsion of subendocardial and epicardial myocardium in acute myocardial ischemia and reperfusion by speckle tracking imaging

Objective： To evaluate the heart function through measuring the rotation and torsion of subendocardial myocardium,epicardial myocardium and transmural gradient in acute myocardial ischemia and reperfusion in dogs by speckle tracking imaging.Methods： The left anterior descending（LAD） coronary artery of 20 adult healthy hybrid dogs were ligated for 180 minutes followed by reperfusion for 120 minutes.Rotation and torsion of myocardium on apical and basal level right before,immediately after and 60,120 and 180 minutes after LAD occlusion,0,60 and 120 minutes after reperfusion were compared by speckle tracking imaging.Results：①Rotation of the basal level： with the extension of ischemie time,the change of transmural gradient decreased and recovered rapidly at the time of reperfusion.The change of the transmural gradient was the lowest at the time of reperfusion for 120 minutes.②Rotation of the apical level： the change of the transmural gradient decreased immediately after occlusion,and decreased to the lowest at the time of occlusion for 180 minutes.It increased immediately after reperfusion and increased smoothly at the time of reperfusion for 60,120 minutes.③Torsion： with the extension of ischemie time,torsion angle value of transmural gradient decreased rapidly.It decreased to the lowest at the time of occlusion for 180 minutes and recovered rapidly at the time of reperfusion.Conclusion： Quantitatively analyze local and overall rotation and torsion of subendocardial and epicardial myocardium can evaluate the heart function by speckle tracking imaging.The peak values of rotation and torsion of subendocardial myocardium,epicardial myocardium and transmural gradient are the useful method to evaluate the wall motion and heart function in acute myocardial ischemia and reperfusion dogs.