Acute In Vivo Functional Assessment of a Biodegradable Stentless Elastomeric Tricuspid Valve.

Degradable heart valves based on in situ tissue regeneration have been proposed as potentially durable and non-thrombogenic prosthetic alternatives. We evaluated the acute in vivo function, microstructure, mechanics, and thromboresistance of a stentless biodegradable tissue-engineered heart valve (TEHV) in the tricuspid position. Biomimetic stentless tricuspid valves were fabricated with poly(carbonate urethane)urea (PCUU) by double-component deposition (DCD) processing to mimic native valve mechanics and geometry. Five swine then underwent 24-h TEHV implantation in the tricuspid position. Echocardiography demonstrated good leaflet motion and no prolapse and trace to mild regurgitation in all but one animal. Histology revealed patches of proteinaceous deposits with no cellular uptake. SEM demonstrated retained scaffold microarchitecture with proteinaceous deposits but no platelet aggregation or thrombosis. Explanted PCUU leaflet thickness and mechanical anisotropy were comparable with native tricuspid leaflets. Bioinspired, elastomeric, stentless TEHVs fabricated by DCD were readily implantable and demonstrated good acute function in the tricuspid position.

In vivo functional assessment of a novel degradable metal and elastomeric scaffold-based tissue engineered heart valve.

OBJECTIVE: Ideal heart valve solutions aim to provide thrombosis-free durability. A scaffold-based polycarbonate urethane urea tissue-engineered heart valve designed to mimic native valve microstructure and function was used. This study examined the acute in vivo function of a stented tissue-engineered heart valve in a porcine model. METHODS: Trileaflet valves were fabricated by electrospinning polycarbonate urethane urea using double component fiber deposition. The tissue-engineered heart valve was mounted on an AZ31 magnesium alloy biodegradable stent frame. Five 80-kg Yorkshire pigs underwent open tissue-engineered heart valve implantation on cardiopulmonary bypass in the pulmonary position. Tissue-engineered heart valve function was echocardiographically evaluated immediately postimplant and at planned study end points at 1, 4, 8, and 12 hours. Explanted valves underwent biaxial mechanical testing and scanning electron microscopy for ultrastructural analysis and thrombosis detection. RESULTS: All 5 animals underwent successful valve implantation. All were weaned from cardiopulmonary bypass, closed, and recovered until harvest study end point except 1 animal that was found to have congenital tricuspid valve dysplasia and that was euthanized postimplant. All 5 cases revealed postcardiopulmonary bypass normal leaflet function, no regurgitation, and an average peak velocity of 2 m/s, unchanged at end point. All tissue-engineered heart valve leaflets retained microstructural architecture with no platelet activation or thrombosis by scanning electron microscopy. There was microscopic evidence of fibrin deposition on 2 of 5 stent frames, not on the tissue-engineered heart valve. Biaxial stress examination revealed retained postimplant mechanics of tissue-engineered heart valve fibers without functional or ultrastructural degradation. CONCLUSIONS: A biodegradable elastomeric heart valve scaffold for in situ tissue-engineered leaflet replacement is acutely functional and devoid of leaflet microthrombosis.