血流向量成像技术在房间隔缺损右房流场可视化及肺体循环血流量比定量中的价值

目的探讨血流向量成像(VFM)技术观察房间隔缺损(ASD)患者右房流场分布的可行性及定量肺、体循环血流量比(Qp/Qs)的准确性。方法应用VFM观察50例健康体检者(正常组)和30例ASD患者(病例组)右房流场分布;分别应用VFM法及频谱多普勒法测算病例组Qp/Qs值并与右心导管测值比较。结果①正常组剑突下双房切面示收缩期右房内来自上下腔静脉的血流并不直接相汇,而是前旋共同形成顺时针方向的大涡流;病例组整个心动周期右房内涡流受到ASD分流束冲击而消失。②VFM法定量Qp/Qs对角度依赖性不高,正常组VFM法心尖三腔心及五腔心切面Qp/Qs测量均值为0.84～1.15(0.99±0.08),与无左向右分流理论值1吻合;病例组VFM法及频谱多普勒法测得Qp/Qs均值与心导管测值比较差异均无统计学意义〔(2.18±0.48)vs.(2.29±0.76),P=0.29;(2.30±0.91)vs.(2.29±0.76),P=0.86〕。③VFM法Qp/Qs测值与右心导管测值相关性高于频谱多普勒法(r=0.71,P<0.001vs.r=0.38,P<0.05)。④VFM法Qp/Qs测值具有良好的一致性,观察者内及观察者间变异系数分别为9.84%和9.86%。结论 VFM能真实地呈现出右房内血流的流场分布,其定量Qp/Qs较频谱多普勒法更接近于右心导管测值。

Visualization of right atrial flow patterns and quantification of pulmonary to systemic flow ratio in patients with atrial septal defect by vector flow mapping

Objective To evaluate the ability of vector flow mapping(VFM) in visualizing right atrial flow and quantifying pulmonary to systemic flow ratio in patients with atrial septal defect(ASD).Methods VFM was performed on 30 patients with ASD and 50 healthy volunteers.The pulmonary to systemic flow ratio(Qp/Qs) was calculated using VFM and spectral doppler compared with that obtained through oximetric data derived from cardiac catheterization.Results Blood streams from superior and inferior caval veins did not collide but turned forward,contributing to a forward clockwise vortex during systole on the subcostal bi-atrial plane in the healthy volunteers.The vortex was disrupted continuously by a left to right shunt in the patients with ASD during the hole cardiac cycle.The Qp/Qs measured by VFM was less angle-dependent in all the cases than the other methods.The mean value of Qp/Qs of the healthy volunteers calculated by apical three-chamber view and apical five-chamber view ranged from 0.84∶1 to 1.15∶1,which is consistent with the theoretical value 1 of no left to right shunts.The values of Qp/Qs of patients with ASD measured by VFM and spectral doppler showed no significant differences with those obtained through oximetric data((2.18±0.48) vs.(2.29±0.76),P=0.29;(2.30±0.91) vs.(2.29±0.76),P=0.86).However,the Qp/Qs value measured by VFM had a better correlation with the oximetric data than that measured by spectral doppler(r=0.71,P<0.001 vs.r=0.38,P<0.05).The inter-observer and intra-observer variability of Qp/Qs measured by VFM was 9.84% and 9.86% respectively.Conclusion VFM can visualize right atrial flow field in patients with ASD and quantify Qp/Qs in a more accurate way than spectral dopler.