Sadasivan Chander, Lieber Baruch B
Department of Biomedical Engineering, University of Miami, Coral Gables, FL.
J Med Device. 2009 Dec;3(4):41005. doi: 10.1115/1.4000453.
The long-term outcome of endovascular coiling of cerebral aneurysms is directly related to the packing density at time of treatment. In general, the highest packing density achievable is only about 45% due to the quasi-random distribution of currently available coils within aneurysms. We investigated whether packing densities could be maximized via more ordered coil configurations. METHODS: Three different coil configurations - circular loops, planar spirals, and spherical helices - were investigated. The packing densities achievable in maximally filling the volume of an exemplar human basilar aneurysm with each coil configuration were calculated numerically. Coil packing simulations were also carried out for aneurysms idealized as spheres over diameters ranging from 2 to 30 mm. RESULTS: The packing densities with the loop, spiral, and spherical helix configurations were 82%, 60%, and 73%, respectively, for the human aneurysm model; the numbers of coils required were 693, 34, and 13, respectively. Simulations within idealized aneurysms suggest that aneurysms cannot be packed to more than 91% with coils of constant circular cross-section. The spherical helix configuration provides a constant packing density (coefficient of variation 0.4%) over the range of aneurysm diameters studied as compared to the two other configurations (coefficients of variation 9% and 8%). CONCLUSIONS: Coil configurations that allow for ordered filling of cerebral aneurysms can potentially provide packing densities that are twice those currently achieved. The spherical helix configuration seems to be the most technically feasible and stable configuration of the three coil types investigated.
脑动脉瘤血管内栓塞的长期疗效与治疗时的填充密度直接相关。一般来说，由于目前可用的弹簧圈在动脉瘤内呈准随机分布，所能达到的最高填充密度仅约为45%。我们研究了通过更有序的弹簧圈构型是否可以使填充密度最大化。方法：研究了三种不同的弹簧圈构型——圆形环、平面螺旋和球形螺旋。通过数值计算得出每种弹簧圈构型在最大程度填充一个典型的人类基底动脉瘤体积时所能达到的填充密度。还对理想化的直径范围为2至30毫米的球形动脉瘤进行了弹簧圈填充模拟。结果：对于人类动脉瘤模型，圆形环、螺旋和球形螺旋构型的填充密度分别为82%、60%和73%；所需的弹簧圈数量分别为693个、34个和13个。在理想化动脉瘤内的模拟表明，使用恒定圆形横截面的弹簧圈，动脉瘤的填充密度无法超过91%。与其他两种构型（变异系数分别为9%和8%）相比，球形螺旋构型在所研究的动脉瘤直径范围内提供了恒定的填充密度（变异系数为0.4%）。结论：能够有序填充脑动脉瘤的弹簧圈构型可能使填充密度达到目前水平的两倍。球形螺旋构型似乎是所研究的三种弹簧圈类型中技术上最可行且最稳定的构型。
