On The Wall Structure Of Woven Vascular Prosthesis For Compliance Requirements

After more than half a century development and studies, woven polyester vascular grafts as an early commercial vascular prosthesis have been widely used in clinic. But one of the main disadvantages is that the compliance of the graft does not match that of the blood vessels. In addition, the grafts do not possess the flexibility and elasticity as human arteries. The documents have introduced, the compliance of the grafts has obvious differences with that of the blood vessels, all of the compliance of the grafts are lower than that of the blood vessels, including, the compliance of the woven polyester vascular is the worst, furthermore, they do not possess the diameter-pressure variation of the body vessel, namely easy to deform under low pressure and small deformation under high pressure, the curve slopes have apparent transition from low to high. Compliance mismatch plays an important role in transplant complications, especially in the anastomosis. Compliance mismatch will increase the probability of thrombus formed in the lumen, which leads to the new lumen thicken, and arteriosclerosis formed in the end of the blood vessel, which is an important reason for vascular grafting failure. Concerning the study on the compliance of vascular prosthesis, in particular, to improve the woven polyester vascular grafts compliance research in our country is almost empty, so the compliance of woven vascular prosthesis have been the urgent problem which needs to be solved currently.In order to improve the compliance of woven vascular prosthesis, the paper uses polytrimethylene terephthalate (PTT) filament as weft yarn, using its lower tensile modulus and good elastic recovery ability to enhance the compliance. Then test the compliance of PTT vascular prosthesis, comparing with the PET vascular prosthesis largely used in clinic, the compliance are improved observably. On that basis, to match the compliance of the body vessels, according to the diameter-pressure curve of body vessel, and considered in terms of the organization-structure, the paper designs an inner-outer binding bilayer fabric. Binding structure makes the two layers fabrics together by the way of woven. Outer and inner layers respectively uses PET and PTT filaments as weft, and make use of the different weft shrinkage to form the bilayer woven fabric structure with different weft length in inner and outer layers. And in accordance with the devised structure and weaving parameters, weave the samples on the continuity rigid rapier loom, which has a self-developed multi-shuttle box. By the way of changing the weaving technics constantly, get the satisfying samples finally. Through appearance analysis and cross-sectional microscope observation, the results indicate that the actual structure has achieved the goal for devised structure. Analyzing the samples' tensile curves within the tensile load, the curve slopes have apparent transition from low to high and meet the requirements of the body vessel in diameter-pressure variation, that prove the validity of fabric structure design method. Finally, in terms of weaving shrinkage and heating shrinkage, the various influence factors on length difference formation between outer and inner layers have been discussed in detail, to lay the foundations for further research on the compliance improvement of woven vascular prosthesis.