Evaluation of right ventricular function using conventional and real-time three-dimensional echocardiography in healthy dogs and dogs with myxomatous mitral valve disease.

To compare conventional and three-dimensional (3D) echocardiographic indices of right ventricular (RV) systolic function in dogs with various stages of myxomatous mitral valve disease (MMVD), classified according to the 2009 guidelines of the American College of Veterinary Internal Medicine (ACVIM), with those from normal dogs. Seventy-eight unsedated dogs (22 healthy controls, 23 ACVIM stage B1 MMVD, 20 ACVIM stage B2 MMVD, and 13 ACVIM stage C MMVD) were included in the study. All dogs underwent conventional and 3D echocardiography. Three-dimensional RV end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were recorded. Right ventricular EDV, ESV, and SV were indexed to bodyweight. Echocardiographic variables were compared across groups using a Kruskal–Wallis test with subsequent post hoc analysis using Dunn's method for multiple comparisons between groups. A P-value of <0.05 was considered significant. Right ventricular EDV was smaller in stage B1 (P=0.012), stage B2 (P=0.035), and stage C (P=0.004) dogs than in controls. Stage B2 (P=0.003) and stage C (P<0.001) dogs had smaller RV ESV than controls. Stage B1 dogs had smaller RV SV than controls (P=0.012). Right ventricular EF was greater in stage C dogs than in controls (P=0.003) and in stage B1 (P=0.017) dogs. Several 3D echocardiographic indices of RV systolic function differ between dogs with advanced MMVD when compared with normal dogs. Further investigation is required to determine if these differences have clinical implications. [ABSTRACT FROM AUTHOR]