Study On The Left Ventricular Myocardial Function Changes In The Early Stage Of Acute Myocardial Ischemia Using Speckle Tracking Imaging And Myocardial Contrast Echocardiography In Rabbits

Objective: Combined speckle tracking imaging(STI)and myocardial contrast echocardiography(MCE)to evaluate left ventricular(LV)myocardial function in the early stage of acute myocardial ischemia(AMI)in rabbits by measuring the LV strain and myocardial perfusion parameters.Methods: 36 New Zealand white rabbits were enrolled for the experiment,the LV branch of coronary artery was ligated to build an AMI model.In the low MI mode,15 cardiac cycles of parasternal LV long-axis,apical four-,three-and two-chamber views were acquired before operation(which was called preoperation group)and 10 minutes after AMI was built(which was called postoperation group)for analysis.Global and segmental peak systolic longitudinal strain(LS)of LV was analyzed by STI.Myocardial blood volume(A),velocity(β)and myocardial blood flow(MBF)were assessed by MCE.Results: 33 acute myocardial ischemia rabbits model were used for Statistical analysis and electrocardiogram shows ST segment and T wave changes.1.Heart rate was impressively decreased after blocking LV branch of coronary artery.(P＜0.05)Interventricular septal thickness(IVST),left ventricular posterior wall thickness(LVPWT),left ventricular end-diastolic dimension(LVDd)and left ventricular ejection fraction(LVEF)show no significantly changes before and after the LV branch of coronary artery was ligated(P>0.05).2.The global longitudinal strain was downregulated after the LV branch of coronary artery was ligated(P＜0.05).Additionally,the LS of left anterior septum wall,anterior wall,lateral wall,posterior wall,inferior middle wall,and apex sections were significantly lowed in preoperation(P＜0.05).Furthermore,the LS of inferior wall,basal posterior septum wall,and middle posterior septum wall were no significant differences.(P＞0.05).3.The myocardial perfusion parameters of LV between postoperation and preoperation had significant differences(P＜0.05),however,the A value of inferior and posterior septum wall had no significant difference.4.The changes of LV LS percent were positively correlated with MBF of left anterior septum,anterior,lateral,inferior,posterior and posterior septum walls(r were0.58、0.56、0.65、0.62、0.56、0.36,P＜0.05).5.Strength of agreement of the inter-observer and intra-observer analysis for LS and MBF of left anterior septum wall,anterior wall and lateral wall accorded well with the experimental results.Conclusion: The STI and MCE technology showed highly sensitivity and good correlation for valuating left ventricular(LV)myocardial function in the early stage of acute myocardial ischemia.Moreover,MCE technology could semi-quantitatively analyze abnormal wall movements in the early stage of ischemia and make up poor image quality during STI analysis.Improved the image quality and increased the number of segments could enhance the accuracy of myocardial strain results.In conclusion,combined STI and MCE can reflect the changes of LV myocardial function in the early stage of acute myocardial ischemia sensitively.