Study of left ventricular transmural mechanics at peri - infarct myocardium in vivo using tissue Doppler strain imaging / 中华超声影像学杂志

ABSTRACT

Objective To observe left ventricular transmural peak radial strain and strain time-to-peak of peri-infarct different layers myocardium using tissue Doppler strain imaging, to assess its mechanical pattern during acute myocardial ischemia.Methods Left anterior descending coronary artery (LAD) were ligated in experimental open-chest Beagle dog models (n = 9),the two-dimensional apical short-axis views of left ventricle in three complete cardiac cycles were acquired and stored in TDI-Q workstation at baseline(the control group of peri-infarc myocardium) and during acute myocardial ischemia respectively.Sampling volume was uesd to measure the peak radial strain and the strain time-to-peak consesquently on the derived M -mode tissue Doppler velocity images at peri-infarct myocardium before and after ischemic segments and different layers(subendocardium, medium, subepicardium).Statistical analies was performed using student's t- test or Pearson's correlations.Results Peak radial strain decreased at peri-infarct subendoeardium (P<0.05) with no significant difference between those at baseline and at peri-infarct medium (P >0.05), the peak radial strain increasd at peri-infarct subepieardium (P < 0.05) ,and the strain time-to-peak at different layers of peri-infarct myoeardium was significantly postponed (P< 0.05).There was a good correlationship of peak radial strain between subendocardium and segment as well as between the medium and segment (r = 0.617, P<0.01 ; r = 0.556, P<0.01).This correlationship disappeared at peri-infarct myocardial segment (r = 0.287, P > 0.05, r = 0.243, P > 0.05).Conclusions The left ventricular transmural mechanical remodeling at peri-infarct myocardium is the integrant of result of mechanical interactions between ischemic and nonischemic myocardium,which might be one of the trigger the structural and fundational remodeling processes involving in the pathophysiological foundation of ischemie cardiomyopathy.