Abstract 4734: Echodynamography is a Novel Useful Technique 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 (LV) during late systolic phase produces greater LV elastic recoil force and brings faster LV relaxation. Echodynamography (ALOKA) is a novel technique that enables us to obtain the flow velocity vector from conventional color Doppler velocity data on the range of interest at any phase of cardiac cycle without angle dependency. We investigated whether the flow velocity vector obtained at LV outflow tract (LVOT) in late systole had a relation with IF and invasively obtained LV relaxation parameters.
Method: Study subjects were consecutive 26 patients who underwent diagnostic cardiac catheterization and conventional color Doppler imaging on the same day. Color Doppler image was acquired in the apical 3-chamber view. The analyses for flow velocity vector were performed offline using an echo image analyzer. The late systolic velocity of the blood flowing was obtained as an average value of the LVOT (VLVOT−late systole). LV pressure was obtained using a catheter-tipped micromanometer. From the recorded pressure waves, first derivative of LV pressure (dP/dt) and a time constant τ of LV pressure decay during isovolumic relaxation were calculated. From LV pressure-dP/dt relationships (phase loop), IF was determined.
Results: A significant positive correlation was observed between the VLVOT-late systole and IF (r=0.75, p<0.0001). The VLVOT-late systole also had significant correlations both with peak negative dP/dt (r=0.49, p<0.05) and the time constant τ (r=−0.70, p<0.0001).
Conclusion: This study indicates that the VLVOT-late systole, which may be a noninvasive substitute for IF, has significant correlations with the parameters of LV relaxation. Echodynamography is a new useful technique to estimate LV early diastolic function.