Echocardiographic assessment of right heart indices in dogs with elevated pulmonary artery pressure associated with chronic respiratory disorders, heartworm disease, and chronic degenerative mitral valvular disease

The aim of this study was to evaluate right ventricular (RV) remodeling and right heart failure associated with different causes of elevated pulmonary arterial pressure (PAP) in dogs. In total, 169 client-owned dogs with tricuspid regurgitation (TR) and 40 client-owned clinically healthy dogs were included. Dogs with TR were further categorised as suffering from chronic respiratory disorders (CRD), heartworm disease (HWD), mild/moderate chronic degenerative mitral valvular disease (CDMD), and severe CDMD. Among the echocardiographic indices of the right heart, no significant difference in the tricuspid annular plane systolic excursion to aortic root diameter ratio was found among the clinical healthy controls and the four different TR categories. No significant differences in TR peak velocity and pulmonic regurgitation peak velocity were found among dogs in the four different TR categories. The ratio of the right to left ventricular basal diameter in the right ventricular-focused view was significantly higher in dogs with chronic respiratory disorders and dogs with heartworms. Left ventricular compression quantified using the eccentricity index and the ratio of the main pulmonary artery to aortic root diameter were significantly higher in dogs with HWD. Their right ventricular acceleration to ejection time (AT/ET) was significantly lower in dogs with HWD. Based on these findings, we conclude that right heart indices are affected by CRD, HWD, and moderate to severe CDMD. However, right heart indices derived from left heart measurements might be underestimated in dogs with CDMD.