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.