Pulmonary hypertension (PH) may lead to right ventricular (RV) remodeling, dysfunction and right-sided congestive heart failure (R-CHF). RV enlargement and dysfunction are strongly associated with prognosis in humans with PH. Reference intervals for RV size and systolic function have been described in healthy dogs. The aims of this study were to assess RV size and systolic function in dogs with PH and to verify if they are associated with severity of PH.

This was a prospective, multicenter, observational study. We included 138 client-owned dogs: 64 with PH and 74 healthy. PH was classified according to tricuspid regurgitation pressure gradient (TRPG) in mild (TRPG: 36–50 mm Hg; n=18 dogs), moderate (TRPG: 51–75 mm Hg; n=14 dogs) and severe (TRPG >75 mm Hg; n=32 dogs). Fourteen dogs with PH had R-CHF. Echocardiographic evaluation of the RV was obtained from the left apical 4-chamber view optimized for the right heart. RV dimension was evaluated through the RV end-diastolic area (RVEDA) index, calculated as RVEDA divided by body surface area. Echocardiographic indices of RV systolic function were tricuspid annular plane systolic excursion (TAPSE) and RV fractional area change (FAC) normalized for body weight (TAPSEn and FACn, respectively).

RVEDA index was significantly higher in dogs with mild, moderate and severe PH than in healthy dogs (p<0.05 for each contrast). No differences in RVEDA index were found between dogs with moderate and severe PH. RVEDA index was significantly higher in dogs with R-CHF in comparison to dogs without R-CHF (p<0.0001). TAPSEn below the reference interval was found in 1/14 dogs with moderate PH and in 4/32 with severe PH, but did not significantly differ among dogs with mild, moderate and severe PH in comparison to healthy. FACn below the reference interval was found in 4/14 dogs with moderate PH and 6/32 with severe PH, and did not significantly differ between dogs with and without PH, irrespective of the severity. No differences in TAPSEn and FACn were found between dogs with and without R-CHF.

In conclusion, the RVEDA index was increased in dogs with PH and in those with R-CHF, suggesting that it may represent a useful parameter to assess PH severity. Because TAPSEn and FACn were abnormal in only a few dogs with moderate-to-severe PH, these parameters of RV dysfunction do not seem to be linked to R-CHF in this species. Further studies are therefore needed to identify additional factors associated with R-CHF in dogs with PH.

Disclosures

No disclosures to report.