Abstract 18231: Intraventricular Velocity Gradient of the Blood Flow during Isovolumic Relaxation is Useful to Assess Left Ventricular Suction
Introduction: Newly developed software Vector Flow Mapping (VFM, Hitachi-Aloka) enables us to assess the blood flow velocity vectors that are computed from conventional color Doppler (CD) imaging data at any phase of a cardiac cycle without angle dependency. Some previous studies reported that the blood flow toward left ventricular (LV) apex during isovolumic relaxation (IR) phase was observed using CD imaging. We investigated whether the velocity gradient of this flow had any relations with LV systolic and early diastolic function.
Methods: Study subjects consisted of 37 patients who underwent diagnostic cardiac catheterization and CD imaging on the same day. Nine of them had prior myocardial infarction, while remaining 28 had no localized LV wall motion abnormality. CD images were acquired in the apical 3-chamber view using an echo equipment Prosound afla10TM (Hitachi-Aloka). The analyses for flow velocity vector were performed offline using an echo image analyzer (DAS-RS1TM, Hitachi-Aloka). A sampling line was set parallel to blood flow stream during IR from apex to the level of mitral annulus. We obtained the intraventricular velocity gradient during IR (IVG-IR) with respect to distance (that is ∂v/∂x) as follows: peak velocity on the sampling line divided by the distance from apex to the point where the velocity peak was observed. LV pressure wave was obtained using a catheter-tipped micromanometer, and then the first derivative of LV pressure (dP/dt) and a time constant τ of LV pressure decay during IR were calculated. LV volumes were obtained by left ventriculography. LV end-systolic volume was indexed to the body surface area of each patient (LVESVI).
Results: IVG-IR had significant correlations with both peak negative dP/dt and time constant τ (r=0.66, p<0.001 and r=0.70, p<0.001, respectively). Furthermore, the log transformed IVG-IR also had significant inverse correlation with LVESVI (r=-0.75, p<0.001).
Conclusions: This study indicates that good LV contraction enhances LV early diastolic function trough the blood flow toward the LV apex during IR from the base. The IVG-IR may be a surrogate parameter that reflects the magnitude of LV suction.
Author Disclosures: S. Kikuchi: None. K. Wakami: None. S. Kitada: None. T. Sugiura: None. T. Goto: None. T. Tani: None. N. Ohte: None.
- © 2014 by American Heart Association, Inc.