Assessment of left ventricular size and function in horses using anatomical M-mode echocardiography

Abstract

Objective To study the applicability of anatomical M-mode (AMM) for assessment of left ventricular (LV) size and function in horses, evaluate agreement with conventional M-mode (CMM), determine reliability, and establish reference intervals for AMM measurements. Animals 98 horses; 13.1 ± 5.6 years; 538 ± 78 kg. Methods Two-dimensional and M-mode recordings were analyzed retrospectively. Standard LV dimensions and indices of LV function, including time intervals, were measured in CMM and compared with AMM studies in long-axis (lx) and short-axis (sx) views. Results The percentages of measureable cycles were 99%, 97%, and 90% for routine LV studies in CMM sx, AMM sx, and AMM lx mode. For time intervals, ≥ 93% of cycles could be measured using AMM compared to a maximum of 77% using CMM. AMM sx measurements agreed well with CMM sx measurements for LV studies; the agreement of AMM lx with CMM sx was markedly lower. The LV ejection time and the duration of electromechanical systole, but not the LV pre-ejection period and the index of myocardial performance, showed fair agreement between methods. Intraobserver and interobserver measurement variabilities were low for most variables. Conclusions AMM can replace CMM for assessment of LV dimensions in horses, but is not recommended for measurement of time intervals.