超声应变率显像技术估测犬的右心室长轴收缩功能

目的探讨超声应变率显像技术对犬的右心室长轴收缩功能的评估价值。方法采集7只犬心尖四腔心切面右室游离壁在5种不同心肌收缩力状态下的组织多普勒超声图像,同步记录右室等容收缩期最大压力上升速率(maxdp/dt),并作为金指标。QLAB分析软件分别测量长轴方向右室游离壁基底段、中段收缩期平均峰值速度(V)、平均峰值应变率(SR)和平均峰值应变(S),并与右室maxdp/dt作直线相关分析。结果应用多巴酚丁胺(dobutamine)后右室游离壁基底段、中段收缩期V、SR、S增加,应用艾司络尔(esmolol)上述各指标明显下降。与maxdp/dt相关分析表明,右室游离壁基底段和中段收缩期V、SR和S与dp/dt显著相关,但以SR最显著。结论超声应变率显像技术可定量估测右室长轴收缩功能,右室游离壁基底段、中段收缩期SR是无创性估测右室长轴收缩功能的良好指标。

Quantification of Longitudinal Right Ventricular Contractile Function Using Ultrasound Strain Rate Imaging

Objective To study the validation of ultrasound strain rate imaging(SRI) in the quantitative assessment of the longitudinal right ventricular (RV) contractile function.Methods Tissue Doppler images of the longitudinal RV free wall were recorded from the apical 4-chamber view in 7 closed-chest anesthetized mongrel dogs during 5 different inotropic states.Peak dp/dt from the RV isovolumic contraction during the right cardiac catheterization was obtained simultaneously in each inotropic state,and was used as the gold standard of RV contractility.Peak systolic velocities (V),peak systolic strain rates (SR),peak systolic strains (S) at the basal and middle segments of RV free wall from the longitudinal axis were quantitatively measured using commercial QLAB software system respectively.The above peak systolic indices were compared with peak dp/dt by linear correlation.Results The peak systolic indices at the basal and middle segments of the longitudinal RV free wall were increased with the infusion of dobutamine and decreased with the infusion of esmolol.A significant correlation was found between peak RV dp/dt and peak systolic indices of the RV free wall.But the most significant correlation was between the peak systolic SRs and peak dp/dt (with the peak systolic SR at the basal segment r=0.9197,P<0.01;with the corresponding one at the middle segment r=0.9033,P<0.01).Conclusions Ultrasound SRI can quantitatively assess the longitudinal RV contractile function.Peak systolic SRs determined at the longitudinal RV free wall are the strong noninvasive indices of RV contractility.