全世界每年中風人數逐年增加，因血栓堵塞造成缺血性腦中風(acute ischemic stroke, AIS)更是主要原因。機械取栓術(mechanical thrombectomy)為一新興且可有效治療缺血性腦中風的方式。取栓過程為以腦部取栓支架(stent retriever)壓縮至支架輸送系統(stent delivery system)內，再經由微導管(guide catheter)釋放於腦內血栓堵塞處，利用鎳鈦材料支架具有的形狀記憶特性，在人體溫度逐漸擴張嵌進血栓內，再經由支架回收至導管內的同時一併將血栓取出，以恢復腦血管的血流順暢，完成機械取栓術。
　　本研究使用工程模擬軟體ANSYS建立支架擴張使血栓受到擠壓的有限元素分析模型，藉由分析新鮮及老化血栓所具有的不同材料特性，使血栓受取栓支架擠壓後所產生應力及應變分佈的影響。並透過模擬試驗在不同血栓參數情形下，探討血栓受擠壓後達到破裂所需的下壓力。本研究並進一步以有限元素模型分析鎳鈦取栓支架從導管中釋放後所產生的徑向力，並與血栓受擠壓達到破裂所需的下壓力進行比較，探討不同取栓支架設計對穿透血栓能力的影響。
之前的研究中指出取栓支架結構寬度越小能大幅降低支架能嵌進及取出血栓所需之徑向力，因此在本實驗中以模擬五種不同鎳鈦取栓支架之寬度，各別為60μm、80μm、100μm、120μm、150μm之結構，並在結果中成功驗證支架結構寬度越小其能完成取栓的徑向力需求就越低，同時也減少了支架取栓過程造成血管管壁損傷的風險。
本研究針對管徑為4mm血管之血栓阻塞，與在血管中釋放已壓縮至直徑2mm的取栓支架為模擬環境，探討取栓支架可達到穿透血栓並減少傷害血管壁風險的設計條件。當取栓支架從導管釋放時，取栓支架直徑小且擴張徑向力較大；反之，當取栓支架直徑漸漸擴大後，其徑向力漸漸變小。因此當取栓支架穿透血栓到達血管壁時，藉由支架擴張力量減少，達到不傷害血管壁及避免血管破裂，達到更好的支架機械取栓結果。

The number of strokes in the world is increasing year by year. The acute ischemic stroke (AIS) caused by clogging is the main reason of brain strokes. In the process of mechanical thrombus removal, the brain stent retriever is compressed into the delivery system, and then the stent is placed in the brain thrombus blockage through a guide catheter. The stent with the characteristics of nitinol material, with memory alloy properties, is used to release it, and the stent is gradually expanded and embedded in the thrombus due to the influence of human body temperature, and then retrieved into the catheter by the stent. At the same time, the thrombus is removed and the blood flow is restored to complete the mechanical retriever thrombectomy.
This study used engineering simulation software ANSYS and the material properties of fresh and aged thrombus to investigate the stress and strain distribution of a thrombus when a stent expanded and pressed on it by the finite element model (FEM) and simulation. The required forces to reach the thrombus fracture by the stent were calculated by the FEM simulation results according to different thrombus properties. In addition, the radial force produced by a nitinol stent released from a guide catheter were predicted by the FEM simulation. The required forces to reach the thrombus fracture and the radial force produced by the nitinol stent were compared to discuss the thrombus penetration ability of stents with different design.
Previous studies indicated that the smaller strut width of the stent retriever can greatly reduce the required radial force of the stent. In this experiment, nitinol stents with five different strut widths, 60μm、80μm、100μm、120μm、150μm respectively, were studied and the results showed that the smaller the strut width, the lower radial force is required for penetrating the thrombus, and the risk of hurting the vascular wall by the stent is reduced.
This study aimed at the thrombus blockage of a vascular with 4mm diameter, and retrieved by a stent retriever released from a 2mm diameter catheter as the simulated environment to explore the stent design consideration for achieving better mechanical thrombectomy: the stent retriever can penetrate the thrombus and the risk of damaging the vascular wall can be reduced. When the stent retriever is released from the catheter, the stent provides the maximum radial force. In the following, when the stent expands to a larger diameter, the radial force is decreasing gradually. After penetrating the thrombus and reaching the vascular wall, the radial force of the stent becomes small to prevent vascular wall damage and rupture.

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