Evaluation of early left ventricular dysfunction in aortic stenosis patients with normal left ventricular ejection fraction by vector flow mapping / 中华超声影像学杂志

ABSTRACT

Objective:To explore the clinical application value of vector flow mapping (VFM) in assessment of early cardiac dysfunction in aortic stenosis (AS) patients with normal left ventricular ejection fraction (LVEF).Methods:The clinical study consisted of 37 patients with various degrees of AS (LVEF>50%) from October 2015 to February 2017 in Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, including 16 mild to moderate ones (AS1 group ) and 21 severe ones ( AS2 group ). A group of 35 age- and gender-matched healthy volunteers were selected as control group. Using Hitachi Aloka Prosound F75 color Doppler ultrasound diagnostic system, general two-dimensional parameters of left ventricular structure and function were measured. Furthermore, standard dynamic apical long axis view color Doppler flow images during 3 completed cardiac cycles were acquired for DAS-RS1 off-line workstation.Based on time-flow curve(T-F curve) of left ventricle, ECG, and the open-close of valves, the diastole period of left ventricle was divided into the isovolumic relaxation phase(P1), rapid filling phase(P2), slow filling phase(P3), atria contract phase (P4), and total diastolic phase(P0); the systole period was divided into isovolumetric contraction phase (P5), rapid ejecting phase(P6), slow ejecting phase(P7), and total systolic phase(P8). The left ventricular energy loss (EL) of three groups were acquired in all phases.Results:Left ventricular EL ①Three peaks of EL appeared in P2, P4 and P6 respectively and total diastolic EL was almost equal to systolic. ②Compared with control group, the EL values of AS1 group increased in all phases, but only in P4, P7 and P0 with significant differences ( P<0.05). ③Compared with the other two groups, the EL values in AS2 group increased significantly in all phases of AS2 group ( P<0.01). Correlation analysis: ①For control group and AS group, there were both significant positive correlations between P0-EL, P8-EL and LVMI ( r=0.561, 0.585; 0.635, 0.652 respectively; P<0.01). ②There were both significant positive correlations between P2-EL and E, e′( r=0.623, 0.537; 0.576, 0.502 respectively; P<0.01), while P4-EL and A( r=0.482, 0.555, P<0.01). ③There were both significant positive correlations between P0-EL, P8-EL and E/e′( r=0.480, 0.459; 0.673, 0.590 respectively; P<0.01) and negative correlations between P0-EL, P8-EL and LVEF ( r=-0.537, -0.596; -0.569, -0.625 respectively; P<0.01). Conclusions:Quantitative evaluation of left ventricular EL by VFM technique is expected to provide a sensitive indicator for evaluating the cardiac structure and functional status in AS patients with normal LVEF.