速度向量成像技术评价右心室长轴收缩功能的实验研究

Investigation of right ventricular longitudinal systolic function by velocity vector imaging

目的探讨速度向量成像（VVI）对右心室功能检测的可行性及准确性。方法采集7只实验犬在3种不同心肌收缩功能状态下的右室长轴VVI图像，同步记录右室收缩期最大压力上升速率（dp／dtmax），分别测量右室游离壁和室间隔基底段、中间段、心尖段收缩期峰值速度（V）、峰值应变（S）和峰值应变率（SR），并与右心导管检查测定的右室dp／dtmax作相关分析。结果应用多巴酚丁胺后右室应变和应变率明显增加。在酒石酸美托洛尔作用下右室各节段S、SR明显减低。相关分析表明：右室的平均S、SR与dp／dtmax有明显的相关性（r=0．79，0．75；P〈0．01），右室游离壁基底段的S和SR与dp／dtmax的相关性高于其他节段（r=0．83，0．78；P〈0．01）。结论VVI可定量估测右室长轴收缩功能，右室游离壁基底段收缩期S、SR是无创性估测右室长轴收缩功能的良好指标。

Objective To investigate the feasibility and accuracy of velocity vector imaging（VVI） to assess strain and strain rate of right ventricule（RV） during varying myocardial functional states. Methods VVI of the longitudinal RV were recorded in 7 closed-chest anesthetized mongrel dogs from the apical 4-chamber view during 3 different inotropic states. Peak dp/dt from the RV contraction during the right cardiac catheterization,which was used as the gold standard of RV contractility, was obtained simultaneously in each inotropic state. Peak systolic velocities （V）, peak systolic strain rates（SR）, peak systolic strains （S） at the basal, middle and apical segments of RV free wall and septal from the longitudinal axis were quantitatively measured by using VVI software system respectively. Results The peak systolic strain and strain rate of the longitudinal RV free wall and septal were increased with the infusion of dobutamine and decreased with the infusion of metoprolol. A significant correlation was found between peak RV dp/dt and RV mean strain and mean strain rate（ r = 0.79,0.75; P 〈0.01）. Among all RV segments, the peak systolic S,SR of RV basal free wall had the most significant correlation to peak dp/dt （r = 0.83, 0.78; P 〈 0.01 ）. Conclusions Strain rate imaging drived from VVI could quantitatively and sensitively detect the longitudinal RV contractile function. Peak systolic S and SR determined at the longitudinal RV basal free wall were the strong noninvasive indices of RV contractility.