Objectives: To investigate the feasibility of real-time three-dimensional (3D) echocardiographic analysis of right ventricular (RV) function in healthy dogs and to compare conventional and 3D echocardiographic (3DE) indices of RV function in dogs with various stages of myxomatous mitral valve disease (MMVD), classified per the guidelines of the American College of Veterinary Internal Medicine, to those from healthy dogs.

Animals: Twenty-two healthy dogs and 56 dogs with MMVD

Methods: All dogs underwent conventional and 3D echocardiographic examinations. Measurements of 3DE RV function indices including RV end-diastolic volume (EDV), RV end-systolic volume (ESV), RV stroke volume (SV), and RV ejection fraction (EF) were recorded. Measurements of conventional indices of RV function were also obtained. RV EDV, ESV, and SV were indexed to bodyweight (BW) and analyzed using commercially available software.

Results: Three-dimensional RV datasets could be acquired and analyzed in all dogs. Intra- and inter-observer coefficents of variation were > 20% for all 3D RV indices. Right ventricular EDV and ESV were decreased and RV EF was increased in dogs with advanced MMVD when compared to controls. Several conventional echocardiographic indices of RV function also differed between the control group and various MMVD groups.

Conclusions: Real-time 3DE RV assessment is feasible in normal dogs with acceptable intra- and inter-observer variability. Several 3DE indices of RV systolic function differ between dogs with advanced MMVD when compared to normal dogs. Further investigation is required to determine if these differences have clinical implications.