Hemocompatible Tunable Blood Shunt for Norwood Recipients with Single Ventricle Physiology

A. Abstract Hypoplastic Left Heart Syndrome is a congenital heart defect characterized by an underdeveloped left side of the heart. The current practice is staged palliation beginning with the Norwood Procedure, which has a high morbidity rate and constitutes a minimum of 30% of revision surgeries. Norwood procedure is performed within days after birth, redirecting blood between the pulmonary and systemic circulation with a Blalock-Taussig Shunt. The fixed geometry of the shunt doesn’t account for flow ratio changes with patient growth, limiting oxygen delivered to the tissues as the infant grows, leading to death. A new geometrically tunable hydrogel-based blood shunt addresses the limitations of a static shunt by adjusting geometry in proportion to the patient’s growth. Increasing the degree of crosslinking in a hydrogel-coated inner lumen of a shunt causes swelling to decrease, thus increasing lumen diameter, thereby modulating blood flow. This was accomplished through a methacrylated dextran hydrogel crosslinked via photoexcitation of LAP, a near-UV photoinitiator; both are known to be hemocompatible. The design was assessed for hemocompatibility and functionality in vitro using ASTM F75617, ASTM F619, and MATLAB image analysis. The first prototype achieved the correct lumen diameter increase in 5 minutes of near-UV exposure. Hemolysis testing on the hydrogel lumen yielded a nonhemolytic score by ASTM F756-17 for both extract and direct contact testing. By accounting for the changing blood flow in a growing patient with this novel geometrically tunable shunt design, the patient outcome will improve and will mitigate the risk of having to undergo another invasive open-heart procedure.