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

This study investigates the viability of using the subcostal (SC) imaging view, a method common in dogs, for newborn horses, and whether it provides reliable measurements of their aortic flow velocity compared to the conventional parasternal long-axis (LAX) views.

Objective of the Study

• The purpose of the research was to determine the feasibility of applying the SC view, which aligns better with the aortic outflow, in equine echocardiography. Specifically, the study concentrated on its implementation in newborn foals.
• The SC view’s aortic measurements were compared with those obtained using the standard LAX views.

Methodology

• This was a prospective observational study involving twenty-three healthy Standardbred and Warmblood foals aged between 7 hours and 6 days old. The foals underwent transthoracic two-dimensional, M-mode, and Doppler echocardiography in lateral recumbency.
• Aortic valve assessments were performed using three different views: right parasternal long-axis (R-LAX), left parasternal long-axis (L-LAX), and subcostal (SC). The study focused on the aortic diameter at the sinus of Valsalva (AoS D), aortic maximal velocity (AoV Vel), velocity time integral (AoV VTI), and pressure gradient (AoV PG).

Results

• The SC view was found feasible for all foals involved in the study.
• No significant disparity was noted in AoS D among different views. Also, there was no substantial correlation discovered for bodyweight (BW).
• Higher AoV Vel, VTI, and PG were observed with the SC view than the L-LAX view with statistical significance, especially in foals of lower bodyweight.

Conclusions

• Despite the non-randomized transducer site order among the foals and lack of observer blindness during offline measurement, the SC view was deemed a success.
• Based on the research, the SC view can be effectively obtained in recumbent newborn foals providing improved alignment with aortic outflow. Hence, it offers more reliable Doppler flow velocity than the conventional L-LAX view.
• The researchers recommended further investigations into the potential use of the SC view for more accurate Doppler estimation of aortic outflow and more comprehensive cardiac assessment of ill foals.