Experimental Study Of Evaluating Left Ventricular Regional Systolic Function Using Speckle Tracking Echocardiography In Acute Myocardial Infarction Model Of Dogs: Comparison Of Three-dimensional And Two-dimensional Approaches

ObjectiveIn this study, longitudinal strain(LS), circumferential strain(CS), radial strain(RS) of every left ventricular segment of acute myocardial infarction model of dogs were obtained using three-dimensional speckle tracking imaging(3D-STI), to investigate the value of 3D-STI in assessment of left ventricular regional systolic function in acute myocardial infarction model of dogs.MethodsLeft anterior descending(LAD) coronary artery was ligated in 24 adult beagle dogs. Traditional echocardiography indictors before ligation and 180 min after ligation were obtained using conventional ultrasound. LS、CS、RS of every left ventricular segment before ligation and 180 min after ligation, and the time for acquisition and analysis were obtained using two- dimensional speckle tracking imaging(2D-STI) and 3D-STI. After the experiment, left ventricular myocardium were determined by TTC staining and divided into two groups: infarcted myocardial segments and non-infarcted myocardial segments.1 Traditional echocardiography measurements:The LVEF, LVIDd, LVIDs, EDV, ESV before ligation and 180 min after ligation were obtained using conventional ultrasound.2 2D-STI and 3D-STI’s measurements:LS、CS、RS of every left ventricular segment before ligation and 180 min after ligation, and the time for acquisition and analysis were obtained using 2D-STI and 3D-STI.Results1 General situation:There were four dogs died in the course of the experiment. Experimental model of acute myocardial infarction was established successfully in 20 dogs. The success rate is 83%.2 TTC staining results:Experimental model of acute myocardial infarction was established successfully in 20 dogs. After the experiment, left ventricular myocardium were determined by TTC staining and obtained infarcted myocardial segments 68, the non-infarcted myocardial segments 231 and can not be clearly classified segment 21.3 Traditional ultrasound measurement results before ligation and 180 min after ligation:After ligation, the LVIDd, LVIDs, EDV, ESV were larger than before ligation(P<0.05), and the LVEF were lower than before ligation(P<0.05).4 Comparison 2D-STI and 3D-STI’s measurement results before ligation and 180 min after ligation:180min after ligation, the LS, CS, RS of infarcted myocardial segments using 2D-STI and 3D-STI were lower than before ligation(P<0.01). No significant change compared with before ligation in non-infarcted myocardial segments(P>0.05). LS of 3D-STI absolute value was lower than the 2D-STI(P <0.01), CS of 3D-STI absolute value was larger than the 2D-STI(P <0.01). 180 min after ligation, the RS of 3D-STI was lower than that of 2D-STI in infarcted myocardial segments(P<0.05). RS has no significant difference between 2D-STI and 3D-STI in other condition(P>0.05).5 ROC of 2D-STI and 3D-STI:The area under the ROC curve of 3D-STI was larger than that of 2D-STI. The area under the ROC curve of LS of 3D-STI was largest. A cut-off value of-12.56% for LS of the 3D-STI had 77.9% sensitivity and 88.2% specificity in predicting acute myocardial infarction.6 Comparison 2D-STI and 3D-STI’s time:The time for acquisition and analysis of the images by 3D-STI were significantly shorter than that by 2D-STI(P <0.01).7 Repeatability test:LS,RS,CS measured by 2D-STI and 3D-STI showed high inter-observer and intra-observer agreement.Conclusion3D-STI is a convenient,accurate method for evaluating left ventricular regional systolic function.