The Research On The Unevenness And Unexpected Failure Of Textile Based Vascular Prostheses

With the development of standard of living,the composition of meals has changed a lot.This may increase the incidence of blood vessel diseases in a certain extent which could be a killer to health.While at the same time,the request of health is rising with the development of the society.This contradiction promotes the research of properties and designs of textile based vascular prostheses both abroad and at home.For decades,tubular knitted and woven vascular prostheses have been used for the clinical replacement and bypass of large caliber diseased human arteries.However,some cases of unexpected rupture and degradation of textile-based vascular prostheses have been observed in our explanted graft collection and reported which may influence the lifespan of vascular prostheses and be a killer to humans' health.The causes leading to the failures may be various which haven't been reported systematically yet.Three.parts of contents are studied in this research.The one is establish a systematically protocol of evaluation of textile based vascular prostheses. Then evaluate some selected virgin graft according to this protocol and analyze the unevenness properties of the graft.Predictions are made for clinical uses.The third part of this study was done on the collected explanted endovascular prostheses.According to the contents above,two parts of subjects including the virgin vascular prostheses and explanted endovascular prostheses were studied.For virgin vascular prostheses,explicit protocol and specific procedures were completed on the base of ISO7198 and the previous experience of our group.This protocol gives a clear procedure of the evaluation of the virgin vascular prostheses.Three woven,two warp knitted and one weft knitted vascular prostheses were evaluated under the above protocol.The study was undertaken to analyze the material,structure and properties of representative vascular devices.Some unevenness cases were found in black guidelines in woven vascular prostheses and in meshing line in warp knitted vascular prostheses.The results give a clue to the surgeon and the designer of vascular prostheses that more attention should be taken on the unevenness of structure which would cause the unevenness of the biomechanical properties of the grafts and be the weak point of the whole graft leading to clinical failure of medical devices.The other part of the study is about three types of explanted endovascular prostheses.Specific protocols of the evaluation of explanted grafts were made according to ISO and to the characterization of each sample.The changes in structure after implanted for years and some special kinds of ruptures were both analyzed in this research.In a word,in this research,each kind of properties was systematically evaluated and the special kinds of ruptures in the collected explanted endovascular prostheses were also analyzed.The results also give a series of advices for the improvement of the design and forming of vascular prostheses.