Xiang Jianping, Ma Ding, Snyder Kenneth V, Levy Elad I, Siddiqui Adnan H, Meng Hui
*Toshiba Stroke and Vascular Research Center, Departments of ‡Neurosurgery, §Mechanical and Aerospace Engineering, ‖Biomedical Engineering, and ¶Radiology, University at Buffalo, State University of New York, Buffalo, New York.
Neurosurgery. 2014 Sep;75(3):286-94; discussion 294. doi: 10.1227/NEU.0000000000000409.
A neurovascular flow diverter (FD), aiming at inducing embolic occlusion of cerebral aneurysms through hemodynamic changes, can produce variable mesh densities owing to its flexible mesh structure.
To explore whether the hemodynamic outcome would differ by increasing FD local compaction across the aneurysm orifice.
We investigated deployment of a single FD using 2 clinical strategies: no compaction (the standard method) and maximum compaction across the aneurysm orifice (an emerging strategy). Using an advanced modeling technique, we simulated these strategies applied to a patient-specific wide-necked aneurysm model, resulting in a relatively uniform mesh with no compaction (C1) and maximum compaction (C2) at the aneurysm orifice. Pre- and posttreatment aneurysmal hemodynamics were analyzed using pulsatile computational fluid dynamics. Flow-stasis parameters and blood shear stress were calculated to assess the potential for aneurysm embolic occlusion.
Flow streamlines, isovelocity, and wall shear stress distributions demonstrated enhanced aneurysmal flow reduction with C2. The average intra-aneurysmal flow velocity was 29% of pretreatment with C2 compared with 67% with C1. Aneurysmal flow turnover time was 237% and 134% of pretreatment for C2 and C1, respectively. Vortex core lines and oscillatory shear index distributions indicated that C2 decreased the aneurysmal flow complexity more than C1. Ultrahigh blood shear stress was observed near FD struts in inflow region for both C1 and C2.
The emerging strategy of maximum FD compaction can double aneurysmal flow reduction, thereby accelerating aneurysm occlusion. Moreover, ultrahigh blood shear stress was observed through FD pores, which could potentially activate platelets as an additional aneurysmal thrombosis mechanism.
神经血管分流装置（FD）旨在通过血流动力学变化诱导脑动脉瘤的栓塞闭塞，由于其灵活的网状结构，可产生不同的网孔密度。
探讨通过增加FD在动脉瘤口处的局部压实程度，血流动力学结果是否会有所不同。
我们研究了使用两种临床策略部署单个FD：不压实（标准方法）和在动脉瘤口处最大程度压实（一种新出现的策略）。使用先进的建模技术，我们模拟了将这些策略应用于特定患者的宽颈动脉瘤模型，在动脉瘤口处分别产生相对均匀的无压实网孔（C1）和最大压实网孔（C2）。使用脉动计算流体动力学分析治疗前和治疗后动脉瘤的血流动力学。计算血流停滞参数和血液剪切应力，以评估动脉瘤栓塞闭塞的可能性。
流线、等速线和壁面剪切应力分布表明，C2能增强动脉瘤内血流减少。与C1时的67%相比，C2时动脉瘤内平均血流速度为治疗前的29%。动脉瘤血流周转时间在C2和C1时分别为治疗前的237%和134%。涡核线和振荡剪切指数分布表明，C2比C1更能降低动脉瘤内血流复杂性。在C1和C2的流入区域，FD支柱附近均观察到超高血液剪切应力。
FD最大程度压实的新策略可使动脉瘤内血流减少加倍，从而加速动脉瘤闭塞。此外，通过FD孔隙观察到超高血液剪切应力，这可能潜在地激活血小板，作为另一种动脉瘤血栓形成机制。
