The Fabrication And Compliance Improving Of Small Diameter Bionic Structure Artificial Vascular Graft

Although the large-diameter vascular graft has been commercialized, clinical effect of the vascular graft with small diameter remains a challenge, and thus, it's internationally focused on by the reasearch in vascular surgery related fields. As well as thrombosis and hemal wall stenosis, the compliance mismatch between an implanted artificial graft and its host artery is a major detrimental cause of graft failure, which has been discussed over years. In this paper, the compatibility between silk powder with polyurethane was studied; moreover, some kinds of artificial vascular grafts were prepared, such as polyurethane(PU) artificial vascular graft, silk powder/ polyurethane artificial vascular graft, tubular fabrics enhanced polyurethane artificial vascular graft and tubular fabrics enhanced silk powder/ polyurethane artificial vascular graft, and their biomechanical properties were tested and compared. This work could give some theoretical guidances on designing a reasonable artificial vascular structural or searching for a desirable new material.The results showed that the compatibility between silk powder with polyurethane was not good, but there hardly influence silk powder's application on polyurethane when the ratio of silk powder and polyurethane was low. In addition, wet blend film can maintain more silk powder and more stable mechanical properties than dry blend film. The blend film would lost large numbers of silk powder and its mechanical properties when the ratio of sik powder and polyurethane reached 5/5.A apparatus for radial compliance testing was fabricated based on the physiological environment that blood vessel met. Relevant parameters were set: the liquid flow of intracavitary was 780-850ml/min, intrapleural pressure and pulse rate were 80-120mmHg and 45 times/min respectively. The variables of artificial vascular diameter were collected using a laser testing equipment. In this situation, the testing results were thought to accurate.There were some parameters that were closely related to artificial vascular's mechanical properties, such as the fabrication methods, porous structure, the thickness, the inner diameter, silk powder content and polyester fiber content. The artificial vascular were made in dry method were able to bear higher bursting pressure than in wet method, but were inferior in radial compliance and dimensions stability. Meanwhile, the artificial vascular were made in dry method have dense structure while the artificial vascular were made in wet method have porous structure which was in favour of artificial vascular's dimensions stability, permeability and radial compliance, but, serious peameability was harmful for application of artificial vascular, so it is important to control the size and quantity of pore. the smaller the thickness of artificial vascular, the better the permeability and radial compliance of artificial vascular, and the smaller the breaking strength and the initial modulus of artificial vascular; however, the artificial vascular need enough thickness to seam strength, dimensions stability and bursting pressure of artificial vascular. As the increase of silk powder content, the artificial vascular's structure become loose, and the breaking strength and the initial modulus gradually declined, the permeability and radial compliance ascend, but the radial compliance declined when silk powder content were in excess of 5/5, therefore, it is necessary to choose suitable silk powder content. With the increase of the spandex's content, the tensile properties of artificial vascular fluctuated in a small range, but the permeability and radial compliance increased. Comprehensive analysis the influence factors that related to artificial vascular mechanical properties, a ideal artificial vascular will be fabricated by optimizing design.