Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China.
Stroke. 2013 Jul;44(7):1936-41. doi: 10.1161/STROKEAHA.113.001202. Epub 2013 May 2.
The effect of flow diverter (FD) on hemodynamic changes observed in aneurysms is inevitably affected by the actual structural configuration of deployed FD. We studied the resultant hemodynamic changes after implantation of FDs using computational fluid dynamic simulations based on micro-computed tomography reconstructions in rabbit aneurysm model.
The FDs by micro-computed tomography images and vascular model based on rabbit-specific angiograms in 14 rabbits were reconstructed for computational fluid dynamic studies, and rabbit-specific inlet flow waveforms were used as boundary conditions. The occluded group (n=10) and unoccluded group (n=4) were divided according to the follow-up angiography. Hemodynamic parameters were separately evaluated for significance with respect to FD implantation and healing.
The normalized mean wall shear stress of the aneurysm sac and inflow volume were significantly reduced after FD deployment, and the relative residence time was significantly increased after treatment, without significant differences in mean pressure of aneurysm sac. When compared with the unoccluded group, the average relative residence time increment and percentage of inflow volume reduction in occluded group were higher. Additionally, the inlet of stream after FD deployment in the occluded group was more prevalent near the central region of the neck, whereas in the unoccluded group, it was more likely to occur near the proximal part of the neck.
This study provided the real structural configurations of fully deployed FDs in vivo. We demonstrated the decrease of wall shear stress, inflow volume, increase of relative residence time, and change of inflow stream induced by FD implantation. The higher relative residence time increment, percentage of inflow volume reduction, and location of stream inlet near the central part of the neck may be closely related to healing.
血流导向装置（FD）对动脉瘤内血流动力学变化的影响不可避免地受到实际放置 FD 的结构构型的影响。我们通过基于兔特定血管造影的微计算机断层扫描重建的计算流体动力学模拟研究了 FD 植入后产生的血流动力学变化。
基于 14 只兔子的 FD 的微计算机断层扫描图像和血管模型进行了计算流体动力学研究，并使用兔特定的入口流量波形作为边界条件。根据随访血管造影将闭塞组（n=10）和未闭塞组（n=4）进行分组。根据 FD 植入和愈合情况分别评估血流动力学参数的显著性。
FD 放置后，动脉瘤囊和流入体积的归一化平均壁面剪切力显著降低，治疗后相对停留时间显著增加，而动脉瘤囊的平均压力无显著差异。与未闭塞组相比，闭塞组的平均相对停留时间增量和流入体积减少百分比更高。此外，闭塞组 FD 放置后的入口流更倾向于颈中部，而未闭塞组更倾向于颈近端。
本研究提供了体内完全展开 FD 的真实结构构型。我们证明了 FD 植入引起的壁面剪切力、流入体积减少、相对停留时间增加和流入流改变。更高的相对停留时间增量、流入体积减少百分比和颈中部附近入口流的位置可能与愈合密切相关。
