Alterations of regional myocardial function in a swine model of myocardial infarction assessed by echocardiographic 2-dimensional strain imaging

Background: Tissue Doppler strain and strain rate imaging have been introduced for quantitative assessment of regional myocardial function. These techniques are largely limited to the evaluation of overall longitudinal myocardial function. This study attempted to apply radial strain, circumferential strain, radial displacement, and strain-based torsion analysis to differentiating the infarct, adjacent, and remote zones in a swine model of myocardial infarction. Methods. Seven pigs, body weight 24 to 26 kg, were subjected to myocardial infarction by occlusion of the left anterior descending coronary artery (IAD) and followed up for 8 weeks. Regional radial and circumferential deformations were quantified non-invasively by ultrasonic strain rate imaging before LAD occlusion, LAD occlusion immediately, and 4,6, and 8 weeks after LAD occlusion. Strain-based left ventricular torsion was assessed at the same time points. Results. Both radial and circumferential strains, and torsion, were decreased significantly in the LAD territory areas as a result of myocardial ischemia and infarction. There were no significant changes in radial and circumferential strains, or torsion, in the areas of adjacent and remote zones over time. Conclusions. These findings demonstrate that speckle-tracking strain imaging may be suitable for noninvasive quantification of left ventricular segmental function of ischemic heart disease.