Long-term patency of a polymer vein valve
Midha, Prem Anand
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Chronic Venous Insufficiency (CVI) is a condition in present in almost 27% of adults in which an insufficient amount of blood is pumped back to the heart due to damaged or poorly apposed one-way valves in the leg veins. During forward flow, vein valves allow blood to return to the heart while posing very little resistance to the flow. During gravity-driven reverse flow, normal valves close and prevent blood from flowing backward through the valve. Incompetent, or damaged, vein valves cannot prevent this reverse flow and lead to a pooling of blood at the feet. CVI is a painful disease presents itself in various ways, including varicose veins, ulcerations of the lower extremities, and severe swelling. Current therapies and treatments include compressive stockings, destruction or removal of affected veins, valve repair, and valve transplants. The implantation of prosthetic vein valves is a future treatment option that does not require an invasive surgery, human donor, or lengthy hospital stay. While no prosthetic vein valves are currently commercially available, this thesis describes the design, verification, and validation of a novel prosthetic vein valve. Verification tests include CFD simulations, functional tests, mechanical tests, and in vitro thromogenicity tests. The validation of the device was done through an animal study in sheep external jugular veins. CFD analysis verified that shear rates within the valve support its lower thrombogenicity as compared to a previous vein valve. Benchtop tests demonstrate superiority in short-term patency over a previous polymer valve. In a sheep study, patency was shown at 6 weeks, surpassing many autograft valves and showing great potential to meet the goal of 3 month patency in sheep.