Echocardiographic evaluation of pulmonary vascular resistance in 459 dogs with Doppler-derived pulmonary hypertension.

BACKGROUND

Abnormally high pulmonary vascular resistance (PVR) is prognostically important and a direct therapeutic target. There is a lack of data on PVR in dogs with pulmonary hypertension (PH).

HYPOTHESIS/

OBJECTIVES

Echocardiographic evaluation of PVR in dogs with PH is feasible and clinically useful for more comprehensive characterization of PH and provides valuable information beyond that derived from Doppler-derived PH assessment alone.

ANIMALS: Four hundred fifty-nine client-owned dogs with echocardiographically-determined PH and 38 control dogs.

METHODS

Retrospective cross-sectional study. Eighteen clinical and 46 echocardiographic variables were evaluated. PVR was calculated using 3 equations validated in people. Dogs with precapillary PH (pre-PH), postcapillary PH (post-PH), isolated post-PH (Ipc-PH), and combined post- and pre-PH (Cpc-PH) were compared using common statistical tests for continuous and categorical data.

RESULTS

There were 213 dogs with pre-PH and 246 dogs with post-PH (86 with Ipc-PH, 160 with Cpc-PH). Average PVR (mean ± SD or median/range) was 2.5 ± 0.9 WU, 8.8 (1.5-28) WU, 4.6 (1.2-6.1) WU, and 9.2 (6.1-26.8) WU in control dogs and dogs with pre-PH, Ipc-PH, and Cpc-PH, respectively (P < .001). In 28 dogs with post-PH discordant changes of PVR and systolic pulmonary artery pressure (SPAP) were observed. These dogs had either normal or mildly increased SPAP (48 ± 4 mmHg) and high PVR (8.8 ± 2.1 WU) or high SPAP (80 ± 15 mmHg) and normal PVR (4.4 ± 1.2 WU), identifying dogs where estimation of PVR would be most useful.

CONCLUSIONS AND CLINICAL

IMPORTANCE

Evaluations of PVR might be considered in the clinical assessment of dogs with echocardiographically-determined PH but more study is needed.