Detection of stunned myocardium using speckle tracking echocardiography combined with low-dose dobutamine stress / 中华超声影像学杂志

ABSTRACT

Objective To detect stunned myocardium using low-dose dobutamine stress (DBS)combined with two-dimensional speckle tracking imaging (2D-STI),and to evaluate the difference and characteristics of mechanical parameters in different conditions between stunned myocardium and adjacent normal myocardium.Methods The acute myocardium ischemia/reperfusion (I/R) of anterior wall of left ventricle(LV) was induced with 60 minutes ligation of left anterior descending coronary artery (LAD),and with reperfusion of 120 minutes in 10 open-chest beagle dogs.Dobutamine was administered continuously via vein with two different dose of 5 μg · kg-1 · min-1 and 10 μg · kg-1 · min-1.At baseline,post ischemia/reperfusion,after the first DBS and the second,the gray-scale dynamic images of three cardiac cycle of left ventricular short axis at the levels of mitral annulus,papillary muscle and apex were acquired.The systolic peak of circumferential strain (CS),radial displacement (RD) of eighteen segments of subendocardium and subepicardium were analyzed by Speckle tracking workstation.LV end-systolic dimension(LVIDS),LV end-diastolic dimension (LVIDD),LV eject fraction (LVEF),heart rate (HR),aortic valve forward flow velocity time integral(AV-VTI) were also measured.Results ①There was no statistical significance (P ＞0.05) under the conditions of baseline,post I/R,the first DBS and the second for LVIDD,LVIDS,LVEF,HR and AV-VTI.②Compared with baseline,the peak systolic subendocardium and subepicardium CS,RD decreased significantly at the apex and middle of short-axis anterior wall of LV under the conditions of post I/R;The parameters of the first DBS was significantly increased compared with the I/R (P ＜ 0.05) ; There was no difference between the two DBS and baseline(P ＞0.05).The peak systolic subendocardium and subepicardium CS,RD at the bottom segment of LV were no statistical significance under the four conditions.③There was no difference for anterolateral wall and anterior septum of LV at the level of papillary muscle under the four conditions.Conclusions ①Low-dose DBS combined with two-dimensional speckle tracking imaging can detect stunned myocardium accurately.② After the occurrence stunning myoeardium,the peak systolic subendocardium RD decreased slightly,subepicardium RD was normal,the subendocardium CS of the surrounding myocardium was still normal,and the peak systolic subepicardium CS decreased to some degree.