腔内隔绝术用分支人工血管膜的设计与性能研究

发布时间：2018-05-24 17:16

本文选题：腔内隔绝术人工血管 + 分支人工血管　；参考：《东华大学》2014年博士论文

【摘要】：涉及到分支血管的主动脉瘤及夹层等扩张性疾病,由于其手术危险系数高,是血管外科治疗研究的重点和难点。然而目前用于治疗该类疾病的腔内隔绝术用人工血管在临床应用中的效果并不理想,主要是由于病变部位离心脏较近,手术难度较大,支架释放较难控制；同时由于涉及分支血管,手术方案复杂,容易导致手术操作不成功,造成治疗失败。因此设计并制备手术操作简单的分支人工血管就成为该领域研究的焦点及重点问题,也成为解决涉及分支血管的主动脉疾病的最佳途径。本文针对用于微创治疗的分支人工血管的研究现状和存在的问题,对腔内隔绝术用分支人工血管膜的功能和结构设计、成型以及结构与性能的关系进行了深入研究。通过动物实验、有限元分析和流体力学理论计算,设计了一种具有帽型结构和抛物线曲面形状并且不带金属支架的分支人工血管膜的模型。由在体测量猪主动脉弓和分支动脉血压差的动物实验表明,分支动脉在被封堵前存在着明显的血压差,其数值达到压差均值42.78±5.17mmHg,在腔内隔绝术人工血管的实际释放过程中,其瞬时的压差将远远大于实测的数值。因此根据这个血压差可以设计一种不带金属支架的帽型分支人工血管膜,利用血压差自动突入分支动脉。并利用ANSYS模拟软件,通过有限元方法分析不同曲面函数的应力和形变分布,结果表明,抛物线曲面的结果最优。根据流体力学理论,通过沿程能量损失计算和综合有限元分析,选择了抛物线曲面。因此提出后续分支血管膜设计可采用帽型、无金属支架支撑的、抛物线曲面的制备方案。根据上述确定的最优抛物线曲面函数模型,通过模压成型的方法制备涤纶(PET)机织分支人工血管膜,探索异形分支人工血管膜的表征方法,并研究其几何结构与顶破、径向拉伸、弹性回复等力学性能的关系。选取PET复丝,采用平纹和斜纹两种织物组织通过织造、退浆／致密化过程得到不同密度的织物,利用抛物线曲面的模具制备“帽形”织物再进行热定型即可得PET分支人工血管膜。同时探索了异形分支血管膜的表征体系,测试了模压成型法人工血管膜的几何结构、聚集态结构和力学性能,并对其释放情况进行了体外模拟。由结果可知,经模压法制备的“帽形”分支血管膜试样从帽底至帽顶密度逐步减小,其厚度、克重、结晶度及顶破强度也随之呈现梯度变化；密度较大的斜纹织物试样体现出较好的力学性能；而体外模拟释放试验也表明模压成型的分支人工血管膜在压力作用下,中间区域能够突入分支动脉,保证分支的血供。为了进一步提高分支人工血管膜的力学性能,以及探索新型的加工成型方法,仿真动脉血管的三层结构(内膜、外膜、中膜),内、外膜选用生物相容性较好的多孔聚己内酯(PCL)材料,中膜选用PET网格织物作为增强层,以期提高分支人工血管膜的力学性能。探索了溶液浓度、分子量对多孔膜的影响,SEM结果可知,溶液浓度越小,孔隙率越大：分子量为18万的PCL膜的孔径和孔隙率大于分子量为5万和8万的PCL膜,所有的多孔膜的孔径都在10μm以上,并且是三维贯通的。综合加工工艺,采用了冰乙酸作为PCL材料的溶剂,选择了分子量为18万的PCL作为基材,最大针织网格密度的PET织物作为增强层,用于制备PCL/PET复合分支人工血管膜。采用了压力喷涂和冷冻干燥方法相结合,制备了针织PET网格织物作为中间层以期增强多孔PCL膜的三层分支人工血管膜。同时对成型后PCL分支人工血管膜及PET网格织物增强的复合分支人工血管膜试样进行几何结构,管壁微观结构,顶破强力、径向拉伸、弹性回复、缝合强度等力学性能进行了表征和分析。对比了PCL/PET复合分支人工血管膜与纯PCL分支血管膜的结构与性能,分析了PET网格织物的增强机制,同时比较了单层PET机织分支人工血管膜的研究结果。PCL以及PCL/PET分支人工血管试样的周边区域的管壁厚度值稍大于中央区(帽顶和帽弧)的值,这是由于PCL溶液在重力场的作用下发生微量流延所致,与PET机织分支人工血管膜的结果相似。PCL/PET分支血管膜的SEM照片显示,管壁呈现多孔形貌,并且相互贯穿,孔径10μm以上；同时PCL基体与PET纤维之间相互贯穿,界面相容性较好。由水渗透性实验表明,多孔膜在标准血压下不渗水,因此在植入体内并不发生内漏。人工血管膜材料的力学性能研究结果表明,PCL/PET复合分支人工血管膜的顶破强度、径向拉伸性能、弹性回复性能以及缝合强度均比纯PCL膜材料的性能有明显的提高,网格织物显示了显著的增强作用。同时PCL/PET复合分支人工血管膜的各项力学性能也比单层PET分支人工血管膜有了很大的提高。综上所述,本文利用了腔内隔绝手术过程中主动脉弓与分支之间存在的血压差,设计了无需金属支架支撑的帽状分支人工血管膜,优化了分支人工血管的外形设计,并用两种方法制备了分支血管膜,研究了其结构与性能的关系。该分支血管膜可应用于腔内分支血管的重建,达到一次手术释放,可以降低手术的操作难度。同时丰富了腔内分支人工血管的种类,为临床手术方法提供了更多的选择。
[Abstract]:Because of the high risk factor of operation , it is the focus and difficulty of vascular surgery research . However , the effect of artificial blood vessel used in clinical application is not ideal because of the close proximity of the lesion site to the heart , the difficulty of operation is large , the release of stent is difficult to control ;
At the same time , because the branch blood vessel is involved , the operation scheme is complicated , the operation is not successful , and the treatment failure is caused . Therefore , the branch artificial blood vessel designed and prepared for the operation is the focus and the focus problem of the research in the field , and the optimal route for solving the aortic disease involving the branch blood vessel is also solved .

In view of the present situation and existing problems of branch artificial blood vessels used in minimally invasive treatment , the functional and structural design , formation and structure and performance of branch artificial blood vessels used in endovascular exclusion were studied .

A model of branch artificial blood vessel membrane with cap structure and parabolic curved surface and without metal stent was designed by animal experiment , finite element analysis and fluid mechanics theory .

Based on the above - mentioned optimal parabolic curved surface function model , the artificial blood vessel membrane of polyester ( PET ) weaving branch was prepared by compression molding , and the relationship between the geometric structure and mechanical properties was studied .
High density twill fabric samples showed good mechanical properties .
The in vitro simulated release test also shows that the branch artificial blood vessel membrane can break into the branch artery under the action of pressure , so as to ensure the blood supply of the branch .

In order to further improve the mechanical properties of the branch artificial blood vessel membrane , and to explore the new processing and forming method , the three - layer structure ( inner membrane , outer membrane and middle membrane ) of the artificial arterial blood tube was studied . The structure and properties of the PCL / PET composite branch artificial blood vessel membrane were studied .
The results show that the mechanical properties of PCL / PET composite branch artificial blood vessel membrane are higher than that of single - layer PET branch artificial blood vessel .

In conclusion , the blood pressure difference between the aortic arch and the branch in the intra - cavity isolation procedure is utilized , the shape design of the branch artificial blood vessel is optimized , and the relationship between the structure and the performance of the branch artificial blood vessel is optimized . The branch blood vessel membrane can be applied to the reconstruction of the branch blood vessel in the cavity , thus the operation difficulty of the operation can be reduced .
【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：R318.08

【参考文献】