A novel color M-mode Doppler echocardiographic index for left ventricular relaxation: depth of the maximal velocity point of left ventricular inflow in early diastole

Abstract

Color M-mode Doppler echocardiography (CMD) has been utilized in assessing left ventricular (LV) filling dynamics. We tested a novel CMD index, the depth of the spatiotemporal maximum of early diastolic inflow (D-maxV) in the left ventricle, to clarify its significance in assessing LV diastolic function. In 26 normal subjects and 32 patients with ischemic heart disease, D-maxV was determined with CMD as the distance from the mitral valve opening point to the center of the aliasing area in early diastole. Transmitral flow velocity was measured with pulsed Doppler. During routine catheterization, high-fidelity LV pressure measurements yielded diastolic variables in patients. D-maxV was significantly lower in the patients than the normals (13.0 ± 7.0 vs 23.4 ± 6.8 mm, P < 0.0001). D-maxV exhibited significant linear correlations with the minimal first derivative of LV pressure (r = 0.72, P < 0.01), the time constant of isovolumic relaxation (r = −0.67, P < 0.01), and LV minimal pressure (r = −0.53, P < 0.02) in the patients with wide ranges of peak early to late inflow velocity ratio (0.43–3.9) and deceleration time of early filling (79–293 ms). D-maxV showed an inverse correlation with LV end-diastolic pressure (r = −0.53, P < 0.02) and no significant correlation with mean pulmonary capillary wedge pressure. Moreover, Kaplan-Meier analysis focusing on the patients with myocardial infarction revealed that the group with D-maxV < 10.4 mm (n = 13) exhibited a lower cumulative cardiac event-free rate than that with D-maxV ≥ 10.4 mm (n = 14) (49.4% vs 92.9% at 5 years, P < 0.05). The depth of the spatiotemporal maximum of early diastolic LV inflow velocity reflects LV relaxation and is free of pseudonormalization. Evaluation of the LV relaxation separately from preload may have a prognostic value for myocardial infarction.