Speckle tracking echocardiography in the assessment of mouse models of cardiac dysfunction

Abstract

Two-dimensional (2-D) speckle tracking echocardiography (STE) accurately quantifies circumferential strain ( Scirc) and radial strain ( Srad) in humans and in large and small animals. This study was performed to assess sensitivity of Scirc and Srad to left ventricular (LV) dysfunction in mouse models. We performed 2-D and M-mode echocardiography 1) in 6 mice during superficial and profound isoflurane anesthesia, 2) serially in 12 mice to monitor the development of heart failure induced by transverse aortic constriction (TAC) and in 8 corresponding control mice, and 3) in 26 mice with varying degrees of TAC-induced heart failure and 12 corresponding control mice immediately before euthanasia. Fractional shortening (FS) and LV mass were measured from standard M-mode tracings, whereas Scirc and Srad were derived by STE. Percent fibrosis and myocyte diameters were assessed from whole heart cross-sectional specimens stained by Masson trichrome. Profound isoflurane anesthesia decreased Scirc ( P = 0.027) but not Srad ( P > 0.05). Mice subjected to TAC showed an immediate and sustained decrease in FS ( P = 0.035), Scirc ( P = 0.016), and Srad ( P = 0.012). Scirc showed better correlation with FS ( r = 0.56 and P < 0.0001) and LV mass ( r = 0.42 and P = 0.0003) than Srad ( r = 0.54 and P < 0.0001 for FS and r = 0.37 and P = 0.014 for LV mass, respectively). Percent fibrosis correlated better with Scirc ( r = 0.46 and P = 0.004) than with Srad ( r = −0.32 and P = 0.05), whereas myocyte diameter showed similar correlation with both strains ( r = 0.45 and r = −0.44, respectively, and P = 0.006 for both). STE correctly identifies LV dysfunction and histological changes in mice and can be used for the serial assessment of cardiac remodeling in murine models.