Miyachi S, Izumi T, Matsubara N, Naito T, Haraguchi K-I, Wakabayashi T
Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
Interv Neuroradiol. 2010 Dec;16(4):353-60. doi: 10.1177/159101991001600401. Epub 2010 Dec 17.
The catheter kickback phenomenon often occurs in the last stage of coil packing for cerebral aneurysms. This behavior is considered the result of either a lack of space in the sac or a stiff detaching zone. In order to clarify its mechanism, focused stretch-resistance (SR) coil simulation models were tested. Various commercially available SR coils were inserted into a cylinder or an aneurismal sac made from a silicone tube with a smaller than prescribed diameter. A magnified SR coil model (straight type) of fishing line was created for simulation. Numerical analysis for the changes in coil behavior were verified. All SR coils showed hardening and straightening at the last few millimeters, resulting in catheter kickback. In a magnified coil experiment, straightening was also realized when folding into a narrow cylinder. The SR line coursed in the canal of the first loops and shifted to the outside in the middle portion. Gaps among first coil pitches were enlarged on after insertion into the narrower space. Shortage of the SR line was calculated to reach a maximum of 32%. The straightening phenomenon is due to SR line shortening and subsequent condensation of pitches of the first loops at the coil end. Coil tail flexibility was lost, and the coil behaved as a stiff wire. Straightening is an important factor in the kickback phenomenon. Shorter final SR coils should be selected, and coil designs should be improved.
导管回弹现象常发生在脑动脉瘤弹簧圈填塞的最后阶段。这种现象被认为是由于瘤腔内空间不足或分离区僵硬所致。为了阐明其机制，对聚焦抗拉伸（SR）弹簧圈模拟模型进行了测试。将各种市售的SR弹簧圈插入由直径小于规定值的硅胶管制成的圆柱体或动脉瘤囊中。创建了一个放大的鱼线SR弹簧圈模型（直型）用于模拟。对弹簧圈行为变化进行了数值分析验证。所有SR弹簧圈在最后几毫米处均出现变硬和伸直，导致导管回弹。在放大的弹簧圈实验中，当折叠放入狭窄圆柱体时也会出现伸直现象。SR线在第一圈的通道中走行，并在中间部分向外偏移。插入较窄空间后，第一圈节距之间的间隙增大。计算得出SR线短缺最多可达32%。伸直现象是由于SR线缩短以及随后弹簧圈末端第一圈节距的凝聚。弹簧圈尾部失去柔韧性，弹簧圈表现得像一根硬线。伸直是回弹现象的一个重要因素。应选择较短的最终SR弹簧圈，并改进弹簧圈设计。
