Asai Takumi, Nagano Yoshitaka, Ohshima Tomotaka, Miyachi Shigeru
Department of Neurosurgery, National Hospital Organization, Nagoya Medical Center, Nagoya, Aichi, Japan.
Department of Electronic Control and Robot Engineering, Aichi University of Technology, Gamagori, Aichi, Japan.
J Neuroendovasc Ther. 2022;16(1):12-18. doi: 10.5797/jnet.oa.2021-0023. Epub 2021 May 7.
Coil compaction after aneurysm embolization is one of the major issues associated with aneurysm recurrence. On the presumption that pulsatile stress to the aneurysm is responsible for coil compaction, we developed an experimental model in vitro to visualize the mechanical stresses exerted by blood pressure and pulse and their relation to coil compaction.
A closed-type non-circulation system was developed by installing a syringe that generated pressure at one end of a tube, along with a spherical aneurysm made of silicone and a pressure sensor in the bifurcated end. We installed a fixed-pressure model under a steady pressure of 300 mmHg while the pressure-fluctuation model simulated the pressure variations using a plunger (in a syringe) by using a motor that applied pulsatile stress in the range of 50 mmHg for a 10-ms cycle. We devised four types of aneurysms with different depths and the same coil length. After coil packing, the aneurysms were observed for 3 days (the observation period in the pressure-fluctuation model corresponded to approximately 300 days in real time). The distance from the datum point to the observable coil loops was determined as the initial position, and the temporal change in the distance from that position was measured.
In the fixed-pressure model, the average distance of coil movement was very small (less than ±0.1 mm). In the pressure-fluctuation model, the movement of coils was observed to be significant for the two longest depths (0.11 and 0.14 mm). The maximal dynamic change in coil movement was observed on the second day. The range of movement was observed to decrease thereafter.
Our experimental study enabled the observation of coil movement within a short duration. It examined coil compaction by applying pulsed pressure to the coils at high speeds. Consequently, a shift of the coil loops inside the incompletely occluded aneurysms was detected on applying a pulsed pressure.
动脉瘤栓塞术后弹簧圈压缩是与动脉瘤复发相关的主要问题之一。基于搏动性应力作用于动脉瘤会导致弹簧圈压缩这一假设，我们建立了一个体外实验模型，以观察血压和脉搏施加的机械应力及其与弹簧圈压缩的关系。
通过在一根管子的一端安装一个产生压力的注射器，以及在分叉端安装一个由硅胶制成的球形动脉瘤和一个压力传感器，开发了一种封闭式非循环系统。我们建立了一个固定压力模型，使其处于300 mmHg的稳定压力下，而压力波动模型则通过使用一个马达驱动注射器中的柱塞来模拟压力变化，该马达以10毫秒的周期施加50 mmHg范围内的搏动性应力。我们设计了四种深度不同但弹簧圈长度相同的动脉瘤。弹簧圈填充后，对动脉瘤进行3天的观察（压力波动模型中的观察期实时对应约300天）。将从基准点到可观察到的弹簧圈圈的距离确定为初始位置，并测量该位置距离随时间的变化。
在固定压力模型中，弹簧圈移动的平均距离非常小（小于±0.1毫米）。在压力波动模型中，对于两个最长深度（0.11和0.14毫米），观察到弹簧圈有明显移动。在第二天观察到弹簧圈移动的最大动态变化。此后观察到移动范围减小。
我们的实验研究能够在短时间内观察弹簧圈的移动。它通过高速向弹簧圈施加脉冲压力来研究弹簧圈压缩。因此，在施加脉冲压力时，检测到不完全闭塞的动脉瘤内弹簧圈圈的移位。
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