115. Acute In Vivo Functional Assessment of a Biodegradable Stentless Elastomeric Tricuspid Valve
Garrett N. Coyan1, Lindemberg Silveira Filho2, Yasumoto Matsumura2, Samuel K. Luketich3, William E. Katz1, *Vinay Badhwar4, William R. Wagner2, Antonio D'Amore2 1University of Pittsburgh Medical Center, Pittsburgh, PA;2McGowan Institute for Regenerative Medicine, Pittsburgh, PA;3University of Pittsburgh, Pittsburgh, PA;4West Virginia University, Morgantown, WV
Invited Discussant: *John E. Mayer
Objective: To evaluate the acute in vivo function, mechanics, and thromboresistance of a stentless biodegradable elastomeric tissue engineered heart valve (TEHV) in the atrioventricular position.
Methods: Biomimetic tricuspid valves were fabricated with poly (carbonate urethane) urea (PCUU) by double component deposition (DCD) electrospinning. Valve geometry, leaflet thickness, and mechanical anisotropy were designed to recapitulate properties measured in porcine tricuspid valves. The three commissures were re-enforced with 2-0 braided polyester sutures with a distal loop to secure implanted chordae (Figure 1A). Five Yorkshire pigs underwent sternotomy, cardiopulmonary bypass with bi-caval cannulation, and implantation of the TEHV in the tricuspid position with running 4-0 polypropylene suture and neo-chordal attachment from the suture loop to the papillary muscles. Post-implant epicardial echocardiography was performed prior to closure and extubation. All animals underwent protocolized final epicardial echocardiography and valve explant at 24 hours. Explants underwent gross analysis, histology, and scanning electron microscopy (SEM). Valve leaflet thickness measurements and bi-axial mechanical testing were performed on explanted PCUU leaflets.
Results: All five animals underwent successful stentless tricuspid TEHV implantation and were subsequently extubated within 1 hour of surgery without inotropic/vasoactive medications. One animal was euthanized at 8.5 hours due to post-operative bleeding and delayed tamponade. All other animals reaching the pre-planned 24 hour study endpoint. Immediate post-bypass echocardiography demonstrated mobile valve leaflets without any leaflet prolapse in all 5 animals, with mild regurgitation in all cases. At 24-hours echocardiography demonstrated good leaflet motion, no prolapse, and trace to mild regurgitation in all but one animal that showed moderate regurgitation due to an undersized valve (Figure 1B). Average mean gradient was 2.9 mmHg. Gross analysis demonstrated no thrombosis and retained valve structure (Figure 1C). Histology revealed patches of proteinaceous deposits with no cellular uptake at 24 hours. SEM demonstrated retained scaffold fiber microarchitecture with similar proteinaceous deposits but no demonstrated platelet aggregation. Explanted PCUU leaflet thickness and level of mechanical anisotropy were equal to pre-operative or native tricuspid measurements (Figure 1D).
Conclusions: A bioinspired, elastomeric, stentless TEHV fabricated by DCD demonstrates good acute function and implantability in the tricuspid position. Scaffold-based TEHV technology shows promise as an improved solution for atrioventricular valve replacement. Planned chronic studies will evaluate valve cellular uptake and polymer degradation properties of the PCUU scaffold.