Accurate assessment of right ventricular (RV) structure and function is an integral component of a complete cardiology evaluation in veterinary patients. Assessment of RV performance is particularly important in patients with pulmonary hypertension, congenital heart disease, and acquired myocardial disease affecting the RV. There is evidence in human medicine suggesting RV function is strongly associated with outcomes in many conditions. The aim of this study was to evaluate the accuracy of right ventricular volume (RVV) and function quantification using three-dimensional echocardiography (3DE) compared to electrocardiogram-gated multidetector computed tomography (ECG-gated MDCT).

Six intact hound cross dogs weighing between 19.5–23.8 kg were anesthetized using a standardized protocol and spontaneous ventilation. Each dog underwent an ECG-gated MDCT and complete 3DE examination. Right ventricular end-diastolic volumes (EDV), end-systolic volumes (ESV), stroke volume (SV), and ejection fraction (EF) were measured using software specific for RVV quantification from 3DE and MDCT data sets. Correlation and levels of agreement between methods were determined, and intra- and interobserver variability was assessed for 3DE.

There were no statistically significant differences between SV (p=0.16) and EF (p=0.31) obtained by MDCT and 3DE. There were significant differences between EDV (p=0.03) and ESV (p=0.01) RVV obtained by MDCT and 3DE. No statistically significant difference in HR was noted between methods (p=0.84). The correlation between MDCT and 3DE was very good for EDV and ESV (R=0.87), moderate for EF (R=0.60) and poor for SV (R=0.31). Bland-Altman analysis showed a systematic underestimation of RVV derived from 3DE compared to MDCT, with an average bias of 15 and 10.3 mL for EDV and ESV, respectively. The intra- (EDV 12%, ESV 18%) and interobserver (EDV 14%, ESV 11%) variability was acceptable for 3DE.

The results of this study suggested use of 3DE to measure RVV in healthy dogs was feasible with acceptable reproducibility. Measures of RVV by 3DE underestimate those made by MDCT, therefore absolute volumes of these imaging techniques are not interchangeable. However, there were no significant differences for EF between methods, which suggests that 3DE may be used to evaluate global RV function and monitor trends with disease states. A larger prospective study in dogs with and without cardiac disease is needed to delineate the benefits and constraints of these methods.

Disclosures

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