Small-Diameter Vascular Grafts For Coronary Artery Bypass Grafting And The Hemocompatibility

The clinical application of small-diameter vascular grafts still has problems such as low compliance and unsatisfactory hemocompatibility.Studies have shown that PVA / PAAm hydrogel vascular grafts reinforced with braided stent have good mechanical properties and cytocompatibility.However,hemocompatibility has not been systematically characterized.Therefore,this study intends to first prepare a polyvinyl alcohol(PVA)/ polyacrylamide(PAAm)(5: 8)hydrogel vascular graft material reinforced with braided stent with a stable structure and good mechanical properties and systematically characterize its mechanical properties.Secondly,hemocompatibility will be characterized systematically,including hemolysis,coagulation,blood cell adhesion and plasma calcium recalculation time.Finally,further attempts will be made to prepare hydrogel vascular graft materials capable of releasing NO to lay the foundation for future in vivo experiments.The experimental results and main conclusions obtained in this study are as follows:1.In this study,a small-diameter(inner diameter = 3mm)PVA / PAAm hydrogel vascular graft material reinforced with braided stent was successfully prepared.This material had stable structure,good mechanical properties,and did not swell.When the axial elongation was 50%,the tensile strength reached(273.28 ± 15.08)kPa,which was significantly higher than the tensile strength of the porcine carotid artery of 176 kPa.The circumferential tensile fracture strength was obviously improved,and the burst pressure was calculated to be(2.19 ± 0.18)MPa.The elongation at break reached more than 600 %.The tensile elastic recovery rate and compressive elastic recovery rate were about 90 % and(92.08 ± 5.28)%,respectively,and the suture retention force was(8.65 ± 0.33)N,which was higher than the canine femoral artery(7.88 ± 0.42)N.More importantly,at 80-120 mmHg,the radial compliance of RHVG was(4.58 ± 0.76)%,which was 5.1 times that of commercial e-PTFE vascular grafts,and was close to the radial compliance of natural blood vessels.2.The hydrogel vascular graft material had good hemocompatibility and was suitable as a vascular graft material.The hemolysis rate was 0.028%,which belonged to non-hemolytic material.The anticoagulant performance of this material was good,and the coagulation index was less than 0.3.It had excellent anti-blood cell adhesion properties.The plasma recalcification time curve showed that it had good anticoagulant properties.3.A hydrogel vascular graft material capable of stably releasing NO was successfully prepared,and could release at least 5 days continuously and effectively.In summary,the hydrogel vascular graft material reinforced with braided stent obtained in this study has stable structure,good mechanical properties,and good hemocompatibility.This material does not swell in volume,and has excellent tensile and suture properties,especially the radial compliance is significantly higher than the commercial e-PTFE vascular graft materials.The material is non-hemolytic,nonclotting,non-adherent to platelets and other blood cells,and can prolong clotting time.The stable release of NO may be more conducive to the improvement of anticoagulant properties in vivo.