Lauric Alexandra, Hippelheuser James, Cohen Alex D, Kadasi Laith M, Malek Adel M
Cerebrovascular and Endovascular Division, Department of Neurosurgery, Tufts Medical Center, and Tufts University School of Medicine, Boston, Massachusetts, USA.
J Neurointerv Surg. 2014 Jul;6(6):466-73. doi: 10.1136/neurintsurg-2013-010871. Epub 2013 Aug 8.
Flow induced tangential wall shear stress (WSS) is thought to be involved in aneurysm formation, growth, and rupture. Low WSS was previously associated with rupture, but definitive quantitative analyses remain scant as larger aneurysms are associated with lower WSS regardless of rupture status, and ruptured aneurysms are larger than unruptured aneurysms. Here, the intra-dome WSS was evaluated on 18 internal carotid artery aneurysms, volume matched as ruptured/unruptured pairs in order to remove the confounding effect of size dependence.
Computational fluid dynamic simulations were performed and WSS was evaluated at peak systole, end diastole, and as time averaged over the cardiac cycle. WSS logarithmic scaling was applied to refine value discrimination at extrema. Ruptured/unruptured lesions were statistically evaluated using pairwise t test analysis. The effect of size on WSS was evaluated in parametric models.
In parametric data, there was a statistically significant negative correlation between volume and WSS values. In patient data, mean WSS was not statistically significant but low range WSS values were significantly lower for ruptured aneurysms, regardless of WSS evaluation (time averaged, peak systole, end diastole). Statistically, logarithmic WSS performed better than WSS, with minimum logarithmic WSS at end diastole being the best rupture status discriminator (p=0.001, area under the curve=0.98). Higher range and maximal WSS were not significantly significant.
Aneurysm size is a confounding factor to WSS rupture discrimination, and volume matched analysis is necessary for unbiased evaluation. While these results lend support to the hypothesis that lower WSS induces wall changes which may be associated with rupture, it raises questions regarding the extent of this association, which requires further exploration.
血流诱导的切向壁面剪应力（WSS）被认为与动脉瘤的形成、生长和破裂有关。先前低WSS与破裂相关，但由于无论破裂状态如何，较大的动脉瘤与较低的WSS相关，且破裂的动脉瘤比未破裂的动脉瘤大，因此明确的定量分析仍然很少。在此，对18个颈内动脉动脉瘤的瘤内WSS进行了评估，将其按破裂/未破裂对进行体积匹配，以消除大小依赖性的混杂效应。
进行了计算流体动力学模拟，并在收缩期末期、舒张期末期以及整个心动周期的时间平均值下评估WSS。应用WSS对数缩放来细化极值处的值辨别。使用配对t检验分析对破裂/未破裂病变进行统计学评估。在参数模型中评估大小对WSS的影响。
在参数数据中，体积与WSS值之间存在统计学上显著的负相关。在患者数据中，平均WSS无统计学意义，但无论WSS评估方式（时间平均、收缩期末期、舒张期末期）如何，破裂动脉瘤较低范围的WSS值均显著更低。从统计学上看，对数WSS比WSS表现更好，舒张期末期的最小对数WSS是最佳的破裂状态判别指标（p = 0.001，曲线下面积 = 0.98）。较高范围和最大WSS无显著差异。
动脉瘤大小是WSS破裂判别中的一个混杂因素，体积匹配分析对于无偏评估是必要的。虽然这些结果支持了较低的WSS会引起可能与破裂相关的血管壁变化这一假设，但它也引发了关于这种关联程度的问题，这需要进一步探索。
