Comparison of echocardiographic variables of mitral regurgitation severity to cardiac computed tomography in dogs with degenerative mitral valve disease.

INTRODUCTION/

OBJECTIVES

The aim of the present study was to compare echocardiographic methods that are used to estimate regurgitant volume (RVol) and regurgitant fraction (RF): proximal isovelocity surface area (PISA), pulsed-wave Doppler (PWD), and volumetric methods (from right parasternal long-axis [RPLx] and apical four-chamber [Ap4C] views) to RVol and RF derived by computed tomography (CT) (RVolCT and RFCT) in dogs with degenerative mitral valve disease. The present study also determined the strength of correlation of echocardiographic indices of left atrial (LA) and left ventricular sizes and semiquantitative mitral regurgitation severity variables with RVolCT and RFCT.

ANIMALS, MATERIALS AND

METHODS

Twenty dogs with stage B2 degenerative mitral valve disease underwent a sedated echocardiogram and CT on the same day.

RESULTS

Correlations between RVol_VolumetricRPLx (r = 0.69, P<0.001), RVol_VolumetricAp4C (r = 0.63, P=0.003), RVol_PWD (r = 0.68, P=0.001), and RVolCT were identified, but not RVol_PISA (r = 0.41, P=0.07). Concordance coefficient (rc) for RVol_VolumetricRPLx (0.67; 95% confidence interval [CI], 0.35-0.85) was higher than those for RVol_PISA (0.15; 95% CI, -0.01-0.31) and RVol_PWD (0.16; 95% CI, 0.04-0.28) relative to RVolCT. Correlations between echocardiographic estimates of RF and RFCT were not identified (P≥0.08). Normalized LA dimension, LA volume, end-diastolic left ventricular volume (RPLx and Ap4C), vena contracta width, and velocity time integral ratio of the transmitral valve flow relative to aortic valve flow each correlated with RVolCT and RFCT (P≤0.04).

STUDY LIMITATIONS: Dogs received alfaxalone during CT but not during echocardiography.

CONCLUSIONS

The volumetric method is more comparable to RVolCT than to PISA and PWD methods. In addition to measurements of chamber size, vena contracta width and velocity time integral ratio of the transmitral valve flow relative to aortic valveflow might be clinically useful indices of mitral regurgitation severity.