Evaluation of subendocardial strain and displacement of left ventricle:a canine model with acute myocardial ischemia using velocity vector imaging / 中华超声影像学杂志

ABSTRACT

Objective To assess subendocardial systolic circumferential strain(CS),radial strain(RS)and radial displacement(RD)of left ventricle(LV)in short-axis view and LV global systolic function in open-chest canine model with acute myocardial ischemia using velocity vector imaging(VVI),and to establish their spatial correlationships.Methods Left anterior descending coronary artery(LAD)was ligated for 20 minutes to induce acute myocardial ischemia in 12 open-chest canine model.At baseline and 20 minutes after ischemia,two-dimensional dynamic gray-scale images of three standard left ventricular short-axis views at the levels of mitral annulus,papillary muscle and apex and the images of LV apical fourchamber and two-chamber view were acquired and transfefred to VVI workstation for off-line analysis.Peak systolic CS,RS and RD of eighteen segments and of three global short-axis sections of LV were measured at subendocardium.and LV ejection fraction(LVEF)and stroke volume(SV)were calculated using Simpson's method.The differences and correlationships were analyzed between them.Resuls Compared with the value at baseline,LVEF decreased significantly(P＜0.05)after ischemia.The peak systolic subendocardial CS,RS and RD of the affected segments,global CS,RD at papillary muscle and apex views and global RS at apex view were significantly lower than those at baseline after ischemia(P＜0.05).There was a good linear correlationship between the peak systolic CS and RD of 17 segments(except the middle segment of LV lateral wall after ischemia)and each global short-axis level before and after ischemia(r=0.662-0.995,P＜0.05,P＜0.01 or P＜0.001),The peak systolic RS of six segments and each global short-axis level(except the apex level at baseline)was correlated with RD(r=0.580-0.916,P＜0.05,P＜0.01 or P＜0.001);There was not statistical correlationship between global RDs and SV as well as LVEF.Conclusions Subendocardial circumferential strain and radial displacement may sensitively reflect the changes of regional and global myocardial systolic function induced by acute myocardial ischemia.The significant correlationship between subendocardial circumferential systolic strain and radial displacement might indicate that circumferential deformation of myocardium result in the changes of the radial displacement mainly.