目的:低的壁切应力(WSS)可预测主动脉瘤的生长和破裂。然而,在临床环境中估计WSS是不切实际的,而测量动脉瘤的几何形状是可行的。这项研究调查了肾下主动脉囊状动脉瘤几何形状与WSS之间的关联。
方法:从非动脉瘤开始,患者特异性,主动脉的计算流体力学模型,通过将颈部宽度和囊深度从1cm增加到4cm,可以产生不同几何形状的囊状动脉瘤。纵横比(囊深度和颈部宽度之间的比率)在0.25和4之间变化。峰值WSS,时间平均WSS(TAWSS),在动脉瘤囊内测量振荡剪切指数(OSI)。
结果:将颈部宽度从4cm减小到1cm,使WSS峰值降低了69%,TAWSS峰值降低了83%。将囊深度从1cm增加到4cm,将峰值WSS降低了55%,将OSI降低了37%。纵横比与峰值WSS呈负相关(Rs-0.85,p<0.001)。
结论:在肾下主动脉囊状动脉瘤中,更小的颈部宽度,较深的动脉瘤囊,和较大的纵横比与较低的峰值WSS相关。
BACKGROUND: Low wall shear stress (WSS) is predictive of aortic aneurysm growth and rupture. Yet, estimating WSS in a clinical setting is impractical, whereas measuring aneurysm geometry is feasible. This study investigates the association between saccular aneurysm geometry of the infrarenal aorta and WSS.
METHODS: Starting with a nonaneurysmal, patient-specific, computational fluid dynamics model of the aorta, saccular aneurysms of varying geometry were created by incrementally increasing the neck width and sac depth from 1 cm to 4 cm. The aspect ratio (the ratio between sac depth and neck width) varied between 0.25 and 4. The peak WSS, time-averaged WSS (TAWSS), and oscillatory shear index (OSI) were measured within the aneurysm sac.
RESULTS: Decreasing the neck width from 4 cm to 1 cm decreased the peak WSS by 69% and the TAWSS by 83%. Increasing the sac depth from 1 cm to 4 cm decreased the peak WSS by 55% and the OSI by 37%. The aspect ratio was negatively correlated to peak WSS (Rs -0.85; P < 0.001).
CONCLUSIONS: In saccular aneurysms of the infrarenal aorta, a smaller neck width, deeper aneurysm sac, and larger aspect ratio are associated with lower peak WSS.