Feasibility of strain and strain rate evaluation by two-dimensional speckle tracking in murine model of myocardial infarction

Abstract

Echocardiography has become a useful tool for serial evaluation of cardiac phenotype in mice. We aimed to examine the feasibility and reproducibility of advanced echocardiographic methods: two-dimensional speckle tracking (STE) and tissue Doppler echocardiography (TDE) in assessing strain and strain rate for analysis of myocardial infarction (MI) in a murine model. We examined 10 anesthetized mice (of which five had MI and five had a normal heart) in parasternal short-axis view with the use of an M12L (14 MHz) transducer. The data were analyzed off-line by two independent investigators using standard echocardiographic parameters and radial strain and strain rate from TDE and STE. Reproducibility of analyzed parameters was high. A good correlation was found between strain and strain rate values measured from TDE and STE obtained by two investigators, reaching a correlation coefficient (r) from 0.94 to 0.99 for strain and from 0.90 to 0.98 for strain rate. The correlation coefficients between radial peak systolic TDE-dependent strain/strain rate vs. strain/strain rate measured from STE for anterior and posterior walls were: r=0.33 (P=0.35)/r=0.69 (P=0.03) and r=0.86 (P=0.0012)/r=0.75 (P=0.01), respectively. Values of strain/strain rate reflected well to pathophysiology of MI in mice. We conclude that local myocardial function can be analyzed in mice using STE. This approach is rapid, reproducible and less time-consuming than TDE measurements in normal mice and in the MI model. STE alone, or combined with tissue Doppler imaging, is suitable for computer-assisted measurements of regional myocardial deformation in mice.