Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany.
Research Campus STIMULATE, University of Magdeburg, Magdeburg, Germany.
PLoS One. 2022 Mar 2;17(3):e0264688. doi: 10.1371/journal.pone.0264688. eCollection 2022.
Flow-diverting stents are increasingly used for the minimally-invasive treatment of intracranial aneurysms. However, a correct positioning of such devices can be challenging due to varying vessel diameters as well as the complex anatomy of the neurovasculature. As a consequence, unsuccessful treatment outcomes are increasingly reported requiring an improvement of the understanding of stent-induced flow modification.
To evaluate the effect of different degrees of flow diverter stent malposition on intra-aneurysmal hemodynamic changes, a controlled hemodynamic configuration was created using an idealized intracranial aneurysms model. Afterwards, four different treatment scenarios were reproduced comprising of 1) the ideal treatment, 2) an insufficient wall apposition in the region of the ostium, 3) a distorted device migrating into the aneurysm sac and 4) an inaccurately deployed stent due to wrong release location. For the assessment of the individual flow modifications, high-resolution stereoscopic particle image velocimetry (PIV) measurements were carried out.
The analysis of the precise in-vitro PIV measurements reveals that in all cases a considerable reduction of the cycle-averaged and peak-systolic velocity was obtained. Compared to the untreated aneurysm configuration, the flow reduction ranged from 63% (scenario 4) up to 89% (scenario 3). The ideal treatment reached a reduction of 78%, which is known to be sufficient for a successful therapy. However, inaccurate device positioning leads to increased oscillating flow towards the lateral directions reducing the chances of sufficient thrombus formation.
High-resolution in-vitro PIV measurements enable an accurate quantification of the treatment efficacy for flow-diverting devices. Furthermore, insufficient treatment outcomes can be reproduces allowing for an assessment of intra-aneurysmal hemodynamic changes.
血流导向装置越来越多地用于颅内动脉瘤的微创治疗。然而，由于血管直径的变化以及神经血管解剖结构的复杂性，这些设备的正确定位可能具有挑战性。因此，越来越多的报道称治疗结果不成功，需要提高对支架引起的血流改变的认识。
为了评估不同程度的血流导向支架错位对颅内动脉瘤内血流动力学变化的影响，使用理想化的颅内动脉瘤模型创建了一个受控的血流动力学构型。然后，再现了四种不同的治疗情况，包括 1）理想治疗，2）在口部区域支架壁贴附不足，3）支架变形进入动脉瘤囊，4）由于释放位置错误导致支架放置不准确。为了评估各个流动的改变，进行了高分辨率立体粒子图像测速（PIV）测量。
对精确的体外 PIV 测量的分析表明，在所有情况下，循环平均和收缩期峰值速度都有相当大的降低。与未治疗的动脉瘤构型相比，流量减少范围从 63%（情况 4）到 89%（情况 3）。理想的治疗方法达到了 78%的降低率，这被认为足以成功治疗。然而，不准确的设备定位会导致向侧面的振荡流增加，从而降低形成足够血栓的机会。
高分辨率的体外 PIV 测量能够准确量化血流导向装置的治疗效果。此外，还可以再现治疗效果不理想的情况，从而评估动脉瘤内的血流动力学变化。
