【摘要】：胸主動脈瘤是常見的擴張性主動脈高危疾病。隨著醫(yī)療技術(shù)的發(fā)展,主動脈腔內(nèi)修復(fù)技術(shù)(EVAR)已成為治療胸主動脈瘤的首選治療方案,而腔內(nèi)修復(fù)術(shù)的關(guān)鍵在于人工血管系統(tǒng)的研制。人工血管系統(tǒng)主要包括覆膜支架和輸送系統(tǒng),覆膜支架的選擇在一定程度上影響了治療效果。現(xiàn)階段國內(nèi)在覆膜支架的結(jié)構(gòu)設(shè)計及加工制作方面的研究明顯不足,臨床運用的覆膜支架大部分依靠進口,價格昂貴。覆膜支架分為支架和覆膜材料,支架多為基于NiTi合金超彈性設(shè)計的自膨脹式支架。但目前關(guān)于支架定型工藝的資料比較少,如何調(diào)整合金相變溫度和組織狀態(tài),使支架在體溫下具有良好的超彈性是本論文的重點。 對患者主動脈的MRI掃描圖像進行圖像分割及三維重建,通過實體造型及快速成型技術(shù)得到胸主動脈瘤模型。根據(jù)胸主動脈模型,利用脫模鑄造法制作胸主動脈人工血管模型。利用人工血管模型搭建體外模擬循環(huán)裝置,對覆膜支架進行體外模擬循環(huán)和流體實驗。 本文研究利用短時連續(xù)熱處理工藝來加工NiTi合金支架單元,研究熱處理工藝條件對NiTi合金相變點的影響,利用NiTi合金應(yīng)力-應(yīng)變曲線評價NiTi合金超彈性特性,研究模具熱惰性對支架定型處理的影響,確定了支架單元的定型工藝。選用支架的定型工藝為兩步連續(xù)熱處理：400℃,30min處理后,放入定型模具中,550℃定型處理15min,支架單元定型效果和力學性能最佳,具有優(yōu)異的超彈性。 利用DSC測試支架單元相變溫度為10℃,支架單元在體溫下處于奧氏體狀態(tài),能夠發(fā)生自膨脹,具有良好的超彈性。利用電子萬能試驗機測試支架單元的支撐力,主體支架單元的徑向支撐力為3-5N,迷你環(huán)支架單元和頂端喇叭口支架單元的徑向支撐力為2-3N。對血管壁有適宜的徑向支撐力。 根據(jù)胸主動脈模型設(shè)計了一種新型覆膜支架。選用滌綸作為覆膜材料與定型后的支架單元縫合,縫制覆膜支架。支架為漸細的彎曲覆膜支架,頂端設(shè)有迷你環(huán)及喇叭口支架單元,彎曲支架的內(nèi)側(cè)設(shè)有加強筋。支架設(shè)計更加符合胸主動脈的生理結(jié)構(gòu),便于放入輸送器中,保證支架對于彎曲的胸主動脈具有良好的貼壁性,支架支撐力良好。
[Abstract]:Thoracic aortic aneurysm is a common high risk disease of dilated aorta. With the development of medical technology, (EVAR) has become the first choice in the treatment of thoracic aortic aneurysm, and the key of endovascular repair is the development of artificial vascular system. The artificial vascular system mainly includes covered stent and delivery system, and the choice of covered stent affects the therapeutic effect to a certain extent. At present, the domestic research on the structure design and fabrication of membrane covered stent is obviously insufficient, most of the clinical application of membrane covered stent rely on import, and the price is expensive. The scaffolds are mainly self-expandable ones based on NiTi alloy super-elastic design. However, there is little information about the scaffold shaping process at present. How to adjust the phase transition temperature and the microstructure of the alloy to make the scaffold have good superelasticity at body temperature is the focus of this thesis. The thoracic aortic aneurysm model was obtained by solid modeling and rapid prototyping by segmenting and reconstructing the MRI images of the aorta. According to the model of thoracic aorta, the model of thoracic aortic prosthesis was made by the method of demoulding casting. The artificial vascular model was used to set up an extracorporeal circulation device to simulate the extracorporeal circulation and fluid flow of the coated scaffold. In this paper, the short-time continuous heat treatment process is used to process the NiTi alloy support unit. The influence of the heat treatment conditions on the transformation point of the NiTi alloy is studied. The stress-strain curves of the NiTi alloy are used to evaluate the superelastic properties of the NiTi alloy. The influence of mould thermal inertia on the setting treatment of the bracket was studied, and the setting process of the support unit was determined. The setting process of the support is two-step continuous heat treatment: 400 鈩，

本文編號：2373776