带瓣膜主动脉瓣支架的研制及经导管植入动物实验

目的:研制可经导管植入的带瓣膜主动脉瓣支架,探索经导管植入该瓣膜支架的可行性。方法:采用0.2 mm镍钛记忆合金丝编织内径为15~19 mm的网状支架。取牛心包,经固定处理后,按仿形类比设计的方法修剪成瓣叶,并缝合在支架的远端,制成带瓣膜主动脉瓣支架。所有瓣膜支架行体外冲水实验、释放实验、体外管道内释放及静态实验。小香猪7只,采用经导管逆行的方法行升主动脉内置入瓣膜支架的动物实验。结果:研制的带瓣膜主动脉瓣支架,经体外试验证明瓣膜关闭良好,反向均为中心水流,并明确该瓣膜支架能经导管顺利释放,释放后能迅速完全扩张,在管道内固定牢靠。采用12F~16F的输送导管,6只实验动物经髂总动脉植入,所有瓣膜支架均能顺利跨过主动脉弓达升主动脉,并顺利释放,除1例瓣膜支架释放后未完全扩张、移位外,其余均迅速完全扩张、固定良好。24 h后处死动物解剖,见支架固定,支架内未见血栓。结论:该带瓣膜主动脉瓣支架启闭功能、自膨功能良好,压缩后的体积符合经导管植入的要求,可采用逆行的方法经髂总动脉植入于升主动脉内,释放后能迅速扩张,固定牢靠。

Preparation of valved aortic stent and trans-catheter implantation to ascending aorta in vivo

Objective:To develop valved aortic stent and to assess the feasibility of its trans-catheter implantation to the ascending aorta in vivo. Methods: We designed self-expandable nitinol stents (15-19 mm in diameter) according to the internal diameter of the ascending aorta of Chinese miniswines. Bovine pericardium was cross-linked with 0. 6% glutaraldehyde solution for 36 hours, and then was shaped and sutured into the stents. Fluid passing test, pre-releasing test and static test of pressure in the tube were performed in all devices. The devices were tried to be inserted percutaneously through common iliac artery to deploy in the ascending aorta in 7 Chinese miniswines. Results: In vitro test showed that the closure of the percutaneous valved aortic stent leaflets was satisfactory, and the fluid flow was not restricted in the opposite direction. The devices could be released through the catheter, expanded completely, and be fixed rapidly in the tube. The devices were deployed using 12F-16F catheter and were inserted through common iliac artery in 6 of the 7 Chinese miniswines. All devices were implanted in the desired position, with 6 expanded completely and fixed rapidly in the ascending aorta. One did not expand completely and was displaced. Animals were executed and dissected after 24 hours. All the devices were fixed in the ascending aorta and there were no thrombus. Conclusion: The function of the percutaneous valved aortic stent is satisfactory. The size of compressed device is suitable for catheterization. It can be successfully implanted into the ascending aorta by using a retrograde method through common iliac artery.