Abstract 136: Stent-Supported Prosthetic Vein Valve

Abstract

Background: In chronic venous insufficiency, incompetent valves prevent effective blood return and lead to varicose veins, lower extremity edema, and stasis ulcers. Several surgical interventions have been described, including valve transplantation, but these extensive procedures are only moderately effective and require inpatient hospitalization. Valve replacement technology continues to evolve and this project reports the design, verification, and pre-clinical validation of a new prosthetic vein valve. Methods: A venous valve has been constructed from a hydrogel and bare-metal stent that has the natural open configuration. Design verification was performed by testing competency, flow resistance, mechanical fatigue, and in vitro thrombogenicity. CFD analysis was used to quantify the shear rates within the valve that may induce platelet aggregation. A large animal study has been initiated to evaluate in vivo performance by open implantation into ovine jugular vein followed by periodic venography. Animals were not heparinized during implantation but were maintained on aspirin in the post-operative period. Results: The valve presents little resistance, allowed physiologic flow rates 400-600mL/min, and tolerated up to 2800mL/min. Preclinical testing shows the valve is also competent under physiologic pressures of 35-50mmHg and computed shear stress rates were maintained below 4000s-1. Fatigue testing up to 500,000 cycles did not cause valve damage. Antegrade venography confirmed patency of the venous valve continuing beyond 4 weeks in sheep. Placement in sheep would be much better with catheter placement using endosurgical techniques. Conclusion: This new prosthetic valve design meets physiologic and hemodynamic criteria for clinical use and patency has been maintained at the 4 week time point. Early occlusions may be prevented with operative anticoagulation