Abstract 19200: Intraventricular Velocity Gradient of the Ejecting Blood Flow at Late Systole is a Novel Index in Assessing Inertia Force of Late Systolic Aortic Flow and Left Ventricular Early Diastolic Function
We previously reported that the inertia force (IF) of the blood flowing out of left ventricle at late systole augmented left ventricular (LV) elastic recoil force and brought faster LV relaxation. Vector Flow Mapping (VFM, ALOKA) is a novel technique that enables us to see the intraventricular flow velocity vectors at any phase of cardiac cycle without angle dependency. We investigated whether the intraventricular velocity gradient with respect to distance from the LV apex toward the LV outflow tract (LVOT) at late systole had a relation with the invasively obtained IF and LV relaxation parameters.
Methods: Study subjects consisted of 42 patients who underwent diagnostic cardiac catheterization. Conventional color Doppler images were acquired in the apical 3-chamber view. Analyses for flow velocity vectors were performed offline using the VFM. We obtained the blood flow velocity distribution on the sampling line set from the LV apex to the LVOT and calculated the intraventricular velocity gradient along the line at late systole (IVG-late systole). LV pressure was obtained using a catheter-tipped micromanometer; then, the first derivative of LV pressure change (dP/dt) and a time constant τ of LV pressure decay during isovolumic relaxation were calculated. From LV pressure-dP/dt relationship (phase loop), the IF was determined.
Results: A significant positive correlation was observed between the IVG-late systole and IF (r=0.78, p<0.0001). The IVG-late systole also had significant correlations with both peak negative dP/dt (r=0.64, p<0.0001) and the time constant τ (r=−0.66, p<0.0001).
Conclusions: This study indicates that the IVG-late systole, which may be a noninvasive substitute for the IF, has significant correlations with the parameters of LV relaxation. VFM is a new noninvasive tool for the evaluation of IF of late systolic aortic flow, which can be obtained only invasively, and a tool for the assessment of integration of LV systolic and early diastolic function.
- © 2010 by American Heart Association, Inc.