Novel simple approach for detection of regional perturbations of cardiac function in mouse models of cardiovascular disease

Abstract

Aims: Transthoracic murine echocardiography is a cornerstone of small animal research, but conventional methods cannot detect regional perturbations in cardiac function. Reliable assessment of regional cardiac function would be of value in transgenic models of myocardial disease. Until now automatized algorithms for achieving this suffers from a number of drawbacks. We developed a simple algorithm for rapidly assessing the relative myocardial radial thickening that occurs between end-diastole and end-systole, that is, regional radial transmural end-systolic strain (RTESS).

Methods and results: Echocardiographic assessment was performed in mice at baseline (n = 8), 2 hours postintraperitoneal isoprenaline (ISO) injection (n = 8), and 10 days postmyocardial infarction (post-MI) (n = 6). A >1000 frames/sec cine loop was acquired by the ECG-gated Kilohertz visualization technique in the parasternal short-axis projection at 3 mm below the mitral annulus. Endo- and epicardial borders were traced at end-diastole and end-systole and RTESS was calculated for each of n segments by the algorithm. The intra- and inter-observer coefficients of variation for segmental RTESS assessment were 5.11 and 7.32, respectively. At baseline, average segmental RTESS was 56.75% and RTESS was similar in all cardiac segments regardless of how many segments the heart was divided into. In the akinetic myocardium of MI and ISO mice, 47.36% and 26.22% length of the endocardium, respectively, RTESS was near zero and significantly different from the remaining myocardium.

Conclusion: We describe a simple and straightforward approach to quantify regional myocardial deformation in mouse models of cardiovascular disease.

Keywords: mouse echocardiography; regional transmural end-systolic radial strain; speckle tracking echocardiography.