超声二维应变评价正常人左室扭转和径向位移的初步研究

Assessment of left ventricular twist and displacement in normal subjects by two-dimensional strain

目的应用超声二维应变技术(2DS)探讨正常左室扭转及径向位移运动特征,构建左室-扭转位移环。方法健康成人志愿者58例,取胸骨旁左室心尖和心底短轴观对各水平旋转及径向位移进行定量分析,计算左室扭转及径向位移,构建左室-扭转位移环,并记录心底部与心尖部旋转角度峰值和左室扭转角度峰值及达峰时间,收缩期及等容舒张期左室径向位移。结果正常人扭转运动主要表现为心底部顺时针旋转和心尖部逆时针旋转,心脏整体表现为心动周期内逆时针方向为主的扭转运动。左室扭转-位移环均呈"8"字构型。收缩期及等容舒张期左室扭转与径向位移呈线性相关。结论应用2DS技术可无创性评价正常人左室扭转及径向位移运动特征,构建左室-扭转位移环。

Objective To assess the value of normal left ventrieular twist and radial displacement by two-dimensional strain （2DS）. Methods Fifty-eight healthy volunteers underwent the examination of two-dimensional ultrasound, then basal and apical short-axis images of left ventricular were acquired to analyse each image rotation and radial displacement. LV twist and radial displacement were calculated and LV twist-displacement loop was constructed. And then basal and apical left ventricular peak rotation （Prot）, peak left ventricular twist （Ptw）, time to Prot and Ptw, systole duration time and isovolumic relaxation time of LV radial displacement were separately measured. Results As seen from the apex, the normal LV performs a wringing motion with a clockwise rotation at the base and counterclockwise rotation at the apex. Twist-displacement loops were characterized by a figure of 8 configuration. There were a linear relation between twist and displacement during systole and isovolumic relaxation time （IVRT）. The rate of twist with respect to radial displacement was determined by the slope of loop. The mean value of IVRT slope was larger than the corresponding value of the slope during systole （P〈0.05）. Conclusion LV twist-displacement can be measured noninvasively by 2DS.