Doppler echocardiographic assessment of left ventricular diastolic function in 74 boxer dogs with aortic stenosis

Abstract

Objective To evaluate left ventricular (LV) diastolic function in boxer dogs with aortic stenosis (AS). Background LV relaxation, elastic recoil, filling and stiffness have been found to be abnormal in people with AS and were related to disease severity, clinical signs and prognosis. Methods 2-D, M-mode and Doppler echocardiography was done in 74 boxers with AS (55 with mild AS, 7 with moderate AS and 12 with severe AS) and compared with reference values from 66 normal boxers. Measurements included isovolumic relaxation time (IVRT), peak early (E) and late (A) transmitral filling velocities, mitral E wave deceleration time, peak systolic, and early and late (AR) diastolic pulmonary wenous flow velocities and related variables. In addition, left atrial (LA) function, LV dimensions and hypertrophy and LV systolic performance were assessed. Results Eight dogs (15%) with mild AS had abnormal LV diastolic function, compared with 16 dogs (84%) with moderate or severe AS. Two dogs (3%) had also systolic abnormalities. The flow pattern of delayed relaxation, pseudonormal mitral inflow and restrictive flow were found in 10, 11 and 3 dogs, respectively. IVRT and E:A were heterogeneous in dogs with moderate or severe AS, being either high, normal, or low. Peak AR velocity was significantly higher (p ≤ 0.05) in dogs with severe AS, and the A duration:AR duration ratio was significantly lower (p ≤ 0.05) in dogs with moderate and severe AS compared with the other dogs, suggesting decreased LV compliance, increased LV end-diastolic pressure, and normal or increased LA systolic function. Bivariate linear regression analysis revealed significant correlations between the severity of AS based on Doppler and LV hypertrophy (IVSd: r = 0.61, p ≤ 0.001 and LVPWd: r = 0.46, p ≤ 0.001) and AS severity and A duration: AR duration (r = -0.64, p ≤ 0.001). Conclution In most boxer dogs with moderate or severe AS, LV diastolic function is abnormal even in the presence of normal systolic performance.