Abstract 530: Clinical Significance of the Vortex Observed in the Left Ventricle at End Diastole
Background: A vortex flow in left ventricle (LV) is observed around the mitral valve after atrial contraction. However, it had been uncertain whether the vortex flow could enhance LV ejection flow. Vector Flow Mapping (VFM) is a novel technique to visualize and measure the blood flow in the LV without angle dependency. Accordingly, we investigated this issue using the VFM.
Methods: Study subjects were consecutive 35 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 (Prosound alfa10, Aloka). The analyses for flow velocity vector were performed using an echo image analyzer (VFM, Aloka). A sample line was set perpendicular to the intraventricular septum at the level of the tip of mitral valve. We obtained the peak flow velocity component of vortex crossing the sample line during end diastole (Vvortexed). Parallel (not vortex) velocity component in the LV outflow tract (LVOT) were also obtained on another sample line set along the LVOT during isovolumic contraction period and just after aortic valve opening (VLVOT-ISO and VLOVT-AVO, respectively). LV pressure was obtained using a catheter-tipped micromanometer; then, peak positive dP/dt was calculated. LV volumes were obtained by left ventriculography.
Results: Vvortexed had a significant positive correlation with peak positive dP/dt (r =0.74, p <0.0001). Vvortexed also had significant inverse correlations with LV end-systolic volume index and LV end-diastolic volume index (r =−0.73, p <0.0001 and r =−0.78, p <0.0001, respectively). In addition, Vvortexed had significant correlations with VLVOT-ISO and VLVOT-AVO (r =0.68, p <0.0001 and r =0.47, p <0.01, respectively).
Conclusions: The spinning velocity of the vortex that is observed at the level of mitral valve tip at end diastole is related to LV systolic function and LV chamber size. The vortex may augment blood flowing velocity at the LV outflow at the phase from isovolumic contraction to early ejection, supporting LV ejection performance.