Hemodynamic performance of coil embolization and stent-assisted coil embolization treatments: a numerical comparative study based on subject-specific models of cerebral aneurysms

Hemodynamic characteristics such as blood velocity, blood pressure, flow impingement, wall shear stress and oscillatory shear index are considered to play important roles in the initiation, growth, rupture and recurrence of the cerebral aneurysms. Endovascular therapy is widely implemented to treat the cerebral aneurysms by releasing coils into the aneurysm sac for limiting the blood flow to the sac and stent-assisted coil embolization is adopted to occlude the wide-necked or complex aneurysms. Some researchers believe that stents are not only a mechanical device but may act as a biological system and contribute to vessel wall healing. Hemodynamics simulation helps people understand the effect of hemodynamic characteristics on the recurrence of the coiled aneurysm and it also benefits the interventional planning of neurosurgeons. This study constructed the numerical model for a subject-specific ICA aneurysm treated with stent-assisted coil embolization, which combined the coiled model of the aneurysm with a porous stent placement, and simulated the pulsatile blood flow in these aneurysm models. When a stent was placed across the aneurysm orifice in the coiled aneurysm, the high wall shear stress around the distal aneurysm root was reduced more than that of the coiled aneurysm without a stent. The simulated results point to the conclusion that the stent not only protects the parent artery from occlusion due to extension of coils or thrombosis, but may also reduce the recurrence risk of the stent-assisted coiled aneurysm.

血流动力学特性，如血流速度、血压、血流冲击、壁面剪应力和振荡剪切指数，被认为在脑动脉瘤的发生、生长、破裂和复发中起着重要作用。血管内治疗被广泛用于治疗脑动脉瘤，通过将弹簧圈释放到动脉瘤囊内以限制流向囊内的血流，并且采用支架辅助弹簧圈栓塞来封堵宽颈或复杂动脉瘤。一些研究人员认为，支架不仅是一种机械装置，还可能作为一个生物系统，有助于血管壁的愈合。血流动力学模拟有助于人们了解血流动力学特性对弹簧圈栓塞动脉瘤复发的影响，也有利于神经外科医生的介入规划。本研究针对一个采用支架辅助弹簧圈栓塞治疗的特定个体颈内动脉动脉瘤构建了数值模型，该模型将动脉瘤的弹簧圈模型与多孔支架放置相结合，并模拟了这些动脉瘤模型中的脉动血流。当在弹簧圈栓塞动脉瘤的瘤口处放置支架时，远端动脉瘤根部周围的高壁面剪应力比未放置支架的弹簧圈栓塞动脉瘤降低得更多。模拟结果表明，支架不仅能保护载瘤动脉免受弹簧圈延伸或血栓形成导致的闭塞，还可能降低支架辅助弹簧圈栓塞动脉瘤的复发风险。