Measurement Variation and Repeatability of Echocardiographic Variables Used to Estimate Pulmonary Artery Pressure in Dogs

Background: Pulmonary hypertension (PH) is an important clinical entity in dogs. Pulmonary hypertension is generally identified based on echocardiographic findings, but measurement variation of the variables most often used in this context has not been reported. Objective: To define measurement variation of echocardiographic variables that are used to estimate pulmonary artery pressure. Animals: Four dogs with subclinical tricuspid valve regurgitation were selected from a hospital population. Methods: Prospective descriptive study - dogs were subject to repeated echocardiographic examination by 2 operators. Each dog was echocardiographically examined 12 times, once by each operator during mornings and afternoons of 3 nonconsecutive days. Measurement variation was defined by coefficients of variation and by mean square errors (MSE) from ANOVA models. Repeatability coefficients (RC) were calculated from MSE. Results: Of 50 within-day, between-day, and interoperator coefficients of variation (CVs), 37 were less than 10% and 46 were less than 15%. The range of peak velocity of tricuspid valve regurgitation (VTR) V-TR was 1.87-3.34 m/s. Analysis of variance revealed a significant effect (P < 0.05) of operator for 7 of 10 measurements. Within-operator/between-day/withinsubject and between-operator/between-day/within-subject RCs of V-TR were, respectively, 0.3 and 0.6 m/s. Conclusions and Clinical Importance: With regard to repeatability, VTR is superior to other methods used for echocardiographic estimation of systolic pulmonary artery pressure. When TR is absent, the acceleration time of pulmonary ejection and the acceleration-to-ejection time ratio are alternative measures. A change in V-TR exceeding 0.3 m/s might be outside the range of expected within-operator variation.