Department of Neurosurgery and Neurotraumatology, Jagiellonian University Medical College, Kraków, Poland.
Anaesthesiology and Intensive Care Clinical Department, University Hospital of Krakow, Kraków, Poland.
World Neurosurg. 2023 Dec;180:e69-e76. doi: 10.1016/j.wneu.2023.07.152. Epub 2023 Aug 5.
Tortuosity of intracranial arteries has been proven to be associated with the risk of intracranial aneurysm development. We decided to analyze which aspects of tortuosity are correlated with hemodynamics parameters promoting intracranial aneurysm development.
We constructed 73 idealized models of tortuous artery (length: 25 mm, diameter: 2.5 mm) with single bifurcation. For each model, on the course of segment before bifurcation, we placed 1-3 angles with measures 15, 30, 45, 60, or 75 degrees and arc lengths 2, 5, 7, 10, or 15 mm. We performed computational fluid dynamics analysis. Blood was modeled as Newtonian fluid. We have set velocity wave of 2 cardiac cycles. After performing simulation we calculated following hemodynamic parameters at the bifurcation: time average wall shear stress (TAWSS), time average wall shear stress gradient (TAWSSG), oscillatory shear index (OSI), and relative residence time (RRT).
We found a significant positive correlation with number of angles and TAWSS (R = 0.329; P < 0.01), TAWSSG (R = 0.317; P < 0.01), and negative with RRT (R = -0.335; P < 0.0.01). Similar results were obtained in terms of arcs lengths. On the other hand, mean angle measure was negatively correlated to TAWSS (R = -0.333; P < 0.01), TAWSSG (R = -0.473 P < 0.01), OSI (R = -0.463; P < 0.01), and positively to RRT (R = 0.332; P < 0.01). On the basis of the obtained results, we developed new tortuosity descriptor, which considered angle measures normalized to its arc length and distance from bifurcation. For such descriptor we found strong negative correlation with TAWSS (R = -0.701; P < 0.01), TAWSSG (R = 0.778; P < 0.01), OSI (R = -0.776; P < 0.01), and positive with RRT (R = 0.747; P < 0.01).
Hemodynamic parameters promoting aneurysm development are correlated with larger number of smaller angles located on larger arcs.
颅内动脉迂曲与颅内动脉瘤发展的风险有关。我们决定分析迂曲的哪些方面与促进颅内动脉瘤发展的血流动力学参数相关。
我们构建了 73 个具有单分叉的理想迂曲动脉模型（长度：25mm，直径：2.5mm）。对于每个模型，在分叉前的一段，我们放置了 1-3 个角度，角度大小为 15、30、45、60 或 75 度，弧长为 2、5、7、10 或 15mm。我们进行了计算流体动力学分析。血液被建模为牛顿流体。我们设置了 2 个心动周期的速度波。在完成模拟后，我们计算了分叉处的以下血流动力学参数：时均壁切应力（TAWSS）、时均壁切应力梯度（TAWSSG）、振荡剪切指数（OSI）和相对居留时间（RRT）。
我们发现角度数量与 TAWSS（R=0.329；P<0.01）、TAWSSG（R=0.317；P<0.01）呈显著正相关，与 RRT 呈负相关（R=-0.335；P<0.01）。在弧长方面也得到了类似的结果。另一方面，平均角度大小与 TAWSS（R=-0.333；P<0.01）、TAWSSG（R=-0.473；P<0.01）、OSI（R=-0.463；P<0.01）呈负相关，与 RRT 呈正相关（R=0.332；P<0.01）。基于所获得的结果，我们开发了一种新的迂曲度描述符，该描述符考虑了角度大小与其弧长和与分叉的距离的归一化。对于该描述符，我们发现其与 TAWSS（R=-0.701；P<0.01）、TAWSSG（R=0.778；P<0.01）、OSI（R=-0.776；P<0.01）呈强烈负相关，与 RRT 呈正相关（R=0.747；P<0.01）。
促进动脉瘤发展的血流动力学参数与位于较大弧上的较大数量的较小角度相关。
