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. [ABSTRACT FROM AUTHOR]