The role of apically directed intraventricular isovolumic relaxation flow in speeding early diastolic left ventricular filling

Abstract

Left ventricular (LV) systolic performance has been acknowledged to have a close relation to LV early diastolic filling and LV relaxation. However, the mechanism showing how good LV systolic function enhances the LV early diastolic filling has not been fully elucidated from the viewpoint of intraventricular flow dynamics. Thus, we investigated this issue in 82 patients with suggested coronary artery disease who underwent cardiac catheterization. Apically directed intraventricular isovolumic relaxation flow (IRF) and the propagation velocity of early diastolic filling flow were measured using pulsed and color Doppler echocardiography. LV ejection fraction and LV relaxation time constant tau were obtained in cardiac catheterization. As we were not able to measure the IRF velocity less than 14 cm/s that was limited by a Doppler low-cut filter, we analyzed the data collected from 78 patients with measurable IRF velocity. The IRF velocity significantly correlated with LV ejection fraction (r = 0.74, P <.001) and with LV relaxation time constant tau (r = -0.31, P <.01). The propagation velocity of early diastolic filling flow significantly correlated with the IRF velocity (r = 0.73, P <.001) and also significantly correlated with LV ejection fraction (r = 0.70, P <.001). Good LV systolic performance augments LV early diastolic filling directly, mediated by IRF. A faster IRF velocity may play a role in delivering good LV systolic performance to LV early diastolic filling.