Echocardiographic measurements of right heart size and function in healthy horses

REASONS FOR PERFORMING STUDY: Right ventricular (RV) function is scarcely described in horses. OBJECTIVES: To establish reliable echocardiographic measurements of right heart size and function in horses. STUDY DESIGN: Descriptive study in healthy horses. METHODS: Ten healthy untrained adult trotter horses underwent repeated echocardiography performed by 2 sonographers from right and left parasternal standard and nonstandard views. Nonstandard views included a right parasternal view focused on the right atrium, left parasternal long-axis pulmonary artery view, left parasternal long-axis view focused on the right ventricle including anatomical M-mode of tricuspid annular motion and left parasternal pulsed wave Doppler recording of pulmonary flow. During off-line analysis, 2 observers performed two-dimensional, M-mode, pulsed wave Doppler, tissue Doppler imaging (TDI) and two-dimensional speckle tracking (2DST) measurements of RV size and function. Acquisition and measurement variability were assessed by calculating coefficients of variation (CV) from one-way repeated measures analyses of variance. The degree of variability was classified as low (CV<15%), moderate (CV 15-25%) or high (CV>25%). RESULTS: Most two-dimensional and M-mode measurements of RV, right atrial and pulmonary artery size showed low variability. The two-dimensional, M-mode and pulsed wave Doppler measurements of RV function showed a low to moderate variability. Right ventricular functional measurements by 2DST showed low variability, except for segmental strain rate. Right ventricular functional measurements by TDI showed a low to high variability, with a lower variability for timing than for peak measurements and a lower variability for velocity compared with deformation measurements. CONCLUSIONS: Right heart size and function can be assessed with low variability in horses.