Evaluation on the left ventricular flow field characteristics in patients with obstructive and non-obstructive hypertrophic cardiomyopathy using vector flow mapping

Abstract

Objective To evaluate the left ventricular flow field characteristics in patients with obstructive and non-obstructive hypertrophic cardiomyopathy (HCM) using vector flow mapping (VFM),then assess the left ventricular hemodynamics.Methods 40 patients with HCM were randomly selected as case group,among which 20 patients with left ventricular outflow tract(LVOT) obstruction (group Ⅰ) and 20 patients without LVOT obstruction(group Ⅱ),40 healthy adult volunteers served as control group.The conventional parameters:left ventricular ejection fraction(LVEF),interventricular septal thickness and radial and pressure gradient of left ventricular outflow tract and VFM parameters:left ventricular peak systolic velocity (Vs),systolic flow (Fs),total negative systolic flow (SQ-) and vortex parameters were measured and compared.The correlation between LVOT pressure gradient and VFM parameters were assessed.Results There was no significant difference of LVEF in three groups.Compared with control group,interventricular septal thickness in group Ⅰ and group Ⅱ was much higher(P ＜0.05).Radius in group Ⅰ was much lower than that of group Ⅱ and pressure gradient of LVOT in group Ⅰ was significantly higher compared with group Ⅱ (P ＜0.05).Comparison of VFM parameters:①Compared with control group,SQ-of basal segments in case groups were lower (P ＜0.05),while SQ-of mid and apical segments were higher(P ＜ 0.05),Vs and Fs of all segments increased (P ＜0.05),and number of vortex,vortex diameter and vorticity of obstruction and non-obstruction groups were higher(P ＜0.05).②Compared with group Ⅱ,SQ-of basal segments decreased and SQ-of mid and apical segments increased in group Ⅰ,Vs and Fs of all segments were higher.The number of vortex,vortex diameter were higher in group Ⅰ (P ＜ 0.05).③ Correlation analysis:Fs in apex,the number of vortex relatively correlated with press gradient of LVOT(r =0.60,0.65,respectively).Conclusions VFM can effectively evaluate the flow field characteristics of left ventricle in patients with obstructive and non-obstructive HCM,and Fs in apex,number of vortex were correlated with the degree of obstruction,then further assess the left ventricular hemodynamics quantitively. Key words: Echocardiography; Cardiomyopathy, hypertrophic; Ventricular function, left ; Vector flow mapping