Abstract 16301: Elevated Left Ventricular End Diastolic Pressure Reduces Intraventricular Velocity Gradient of Blood Flow During Atrial Contraction

Abstract

Background: Vector Flow Mapping (VFM, Hitachi-Aloka) is a novel technique that enables us to evaluate the blood flow velocity vectors in the left ventricle (LV) based on conventional color Doppler velocity data at any phase of cardiac cycle without angle dependency. Our hypothesis was that an elevated LV end-diastolic pressure (EDP) disturbs filling of blood from the left atrium (LA) to the LV apex during atrial contraction. We investigated this hypothesis using the VFM.

Methods: Study subjects were consecutive 35 patients with sinus rhythm who underwent diagnostic cardiac catheterization and echocardiographic examination on the same day. Conventional color Doppler images were acquired in the apical 3-chamber view. Frame rate was.ranged from 35 to 50 fps. The analyses were performed using an echo image analyzer (DAS-RS1, Hitachi-Aloka). A sampling line was set parallel to the blood flow stream during atrial contraction from the apex to the level of mitral annulus. We obtained the intraventricular velocity gradient (IVG) with respect to distance (that is ∂v/∂x) during atrial contraction. LV pressure was obtained using a catheter-tipped micromanometer; both the LV pressure just before atrial contraction (preA) and LVEDP were then measured. LV volumes were obtained by left ventriculography.

Results: IVG during atrial contraction had a significant inverse correlation with both preA (r=0.73, p<0.0001) and LVEDP (r=-0.77, p<0.0001). IVG during atrial contraction also had a weak but significant inverse correlation with LV end-diastolic volume index (r=-0.50, p<0.01).

Conclusions: An elevation of LVEDP as well as enlarged LV cavity at end-diastole disturbs the blood flow from the LA to the LV during atrial contraction. This may be related to increased LV filling pressure or mean LA pressure.