Feasibility of the echocardiographic subcostal view in newborn foals: two-dimensional and Doppler aortic findings

Background: In dogs, due to better alignment with the aortic outflow, the subcostal (SC) transducer site provides greater Doppler-derived velocities than those obtained from the left parasternal view. The feasibility of this imaging approach has never been described in equine echocardiography. Objectives: The objective of this study was to evaluate the feasibility of the SC view in newborn foals and compare aortic two-dimensional and Doppler-derived velocity measurements with those of standard parasternal long-axis (LAX) views. Study design: A prospective observational study. Methods: Twenty-three newborn healthy Standardbred and Warmblood foals, aged from 7 h to 6 days, underwent transthoracic two-dimensional (2DE), M-mode and Doppler echocardiography that was performed in lateral recumbency. Right and left parasternal long-axis (R-LAX, L-LAX) and SC views were obtained to perform 2DE and Doppler assessments of the aortic valve (AoV). Aortic diameter at the sinus of Valsalva (AoS D) was measured from R-LAX and SC images. Aortic maximal velocity (AoV Velmax), velocity time integral (AoV VTI) and pressure gradient (AoV PG) were obtained by pulsed wave Doppler spectra from SC and L-LAX views. Results: The SC view was feasible in all foals. No significant difference was found in AoS D between different views (P = 0.06), and no significant correlation was detected for bodyweight (BW). AoV Velmax, VTI and PG obtained from the SC view were greater than from the L-LAX view (P