Introduction

The most frequent cause of pulmonary arterial hypertension (PAH) in the dog is chronic mitral valve disease (CMVD).

Objectives

To identify echocardiographic changes in right ventricle (RV) systolic function at different stages of CMVD and, if tricuspid insufficiency (Tl) is present, to correlate with the Tl velocity. Our hypothesis is that RV systolic function decreases with severity of CMVD, and that it is correlated with PAH estimated by Tl velocity.

Methods

Ninety-six dogs were grouped according to CMVD severity based on thoracic radiographs, echocardiographic evaluation, and clinical signs. The dogs were equally distributed in each group: A, B1, B2 and C, according to American College of Veterinary Internal Medicine staging system. Indicators of RV systolic function were tricuspid annular plane systolic excursion indexed to body surface area (iTAPSE), fractional area change [FAC=(RV max area–RV min area)/RV max area] and S’ wave velocity of RV posterior wall. All parameters were obtained by modified left apical four chamber view. Tl was detected by colour Doppler and its velocity was measured by continuous Doppler echocardiography.

Results

iTAPSE was higher in stage C than control (p=0.001); FAC was higher in stage C than stage B2 (p<0.0001); S’ wave velocity did not differ between the groups (p=0.774). Tl was detected in thirty-two animals (33.3%), and no statistical significant correlation was detected to RV systolic function.

Conclusions

RV systolic dysfunction is not detected in advanced stages of CMVD, and it is not correlated with pulmonary arterial pressure in CMVD.