Application value of vector flow mapping in assessing the degrees of coronary artery stenosis

Abstract

Objective To quantify the left ventricular flow field characteristics of different phases of cardiac cycle in patients with different degrees of coronary artery stenosis by using vector flow mapping (VFM), and explore the value of quantitative parameters of VFM in diagnosis of degrees of coronary artery stenosis in patients with coronary heart disease. Methods Eighty-four patients with coronary artery stenosis showed by coronary angiography served as case group. According to the results of coronary angiography, all the patients of case group were divided into 3 groups: mild stenosis group, moderate stenosis group and severe stenosis group. Forty-five healthy adult volunteers were selected as control group. The quantitative parameters, including average energy loss (EL-base, EL-mid, EL-apex) and circulation (vortex area, circulation), were measured in the different periods of VFM mode. The difference of parameters were evaluated between case group and control group during different periods. E/e′ was derived via dual-Doppler imaging technology and correlation was analyzed between aEL, circulation, E/e′(L) and E/e′(S), separately. ROC curve was used to analyze aEL in severe stenosis group, and to evaluate the diagnostic efficacy of aEL in different cardiac cycles. Results ①Compared with the control group, aEL in global and regional segment of left ventricle in the severe stenosis group were significantly increased during isovolumetric relaxation period, reduced filling period, atrial systolic phase and isovolumic contraction period (all P<0.05). And the aEL in global and regional segment of left ventricular in the moderate stenosis group were significantly increased during reduced filling period, atrial systolic phase and isovolumic contraction period (all P<0.05). And the aEL in middle segment of left ventricular in the mild stenosis group was significantly increased during reduced filling period (P<0.05). ②Compared with the control group, the vortex area and circulation intensity in left ventricular of the severe stenosis group were significantly increased during isovolumetric relaxation period, reduced filling period, atrial systolic phase and isovolumic contraction period(P<0.05). ③In case group, there were positive correlations between aEL with E/e′(L) or E/e′(S) at global and regional segment of rapid filling phase and atrial systolic phase. And there were positive correlations between the vortex area or circulation intensity and E/e′(L) or E/e′(S) during reduced filling period and atrial systolic phase. Conclusions VFM can effectively evaluate the flow field characteristics of left ventricle in patients with coronary heart disease. The quantitative parameters of VFM can reflect the extent of coronary artery stenosis in some extent. Key words: Vector flow mapping; Coronary stenosis; Energy loss; Circulation