Using the subcostal view to measure aortic blood flow in cats

Abstract

INTRODUCTION/OBJECTIVES: In dogs and foals, spectral Doppler-derived aortic outflow velocities (AVs) obtained from the subcostal (SC) view provide higher values than the left parasternal apical five-chamber (LAp) view. In cats, use of the SC view for obtaining AV has not been reported. The aim of the study was to compare AV from SC and LAp views, assess the impact of patient and echocardiographic variables on the difference and confirm the feasibility of obtaining the SC view in cats. The authors hypothesised that the SC view would be well tolerated and provide higher AV. ANIMALS, MATERIALS AND METHODS: This was a prospective, single-centre, observational study in cats referred for echocardiography. Standard echocardiographic studies were performed that included Lap-derived AV and, where feasible, those from the SC view. Patient compliance, ease of attainment and need for sedation were recorded. Aortic velocities obtained from both views were compared. The influences of patient and echocardiographic variables on the differences in AV were determined. RESULTS: Ninety-three cats were enrolled in the study. Eight cats were excluded due to incomplete data. The final analysis included 85 cats. Most cats (81%) tolerated the SC view. Subcostal AVs were greater than LAp velocities by 0.18 m/s (confidence interval &#xb1; 1.25 m/s; P<0.005). Sedation, heart rate, body condition score, bodyweight, aorto-septal angle and left ventricular outflow tract obstruction (LVOTO) did not influence the differences between views. STUDY LIMITATIONS: The study limitations included involvement of only a single-centre, subjective analysis of patients' tolerance, non-standardised sedation protocol, probe frequency and size and a small number of cats included with moderate and severe LVOTO, other cardiac conditions, or receiving treatment. CONCLUSIONS: Aortic velocities derived from the SC view were greater than those from the LAp view in cats. The SC view was well tolerated and may offer a more accurate assessment of LVOTO severity in some cats.