Materials, Design And Manufacturing Of A Growth-accommodating Pediatric Heart Valve Prosthesis: From Ideation To The First-generation Prototype
Richard Li, Jonathan Russ, Pierre-Louis Pousse, Costas Paschalides, Giovanni Ferrari, PhD, Emile Bacha, MD, Haim Waisman, PhD, Jeffrey W. Kysar, PhD, David Kalfa, MD, PhD.
Columbia University, New York, NY, USA.
Objective: Current heart valve prostheses have no growth potential, forcing pediatric patients to receive multiple repeat valve replacements. We aimed to demonstrate the concept of a biostable polymeric valved conduit, designed to be implanted surgically and subsequently expanded by transcatheter balloon to accommodate growth and avoid repeat surgeries.
Methods: The valve leaflets were designed to preserve competence after dilation of the conduit. Two biocompatible polymers, polycarbonate urethane (PCU) and polyurethane-polydimethylsiloxane (PU-PDMS), were mechanically tested for their capacity to permanently deform. A computational model was developed to study the response of the valve material and geometry to dilation. Two valved conduits were fabricated and tested in vitro for hydrodynamics, dilated by transcatheter balloon, and tested again at the larger diameter.
Results: The coaptation height of the valve leaflets was extended by 5 mm to ensure coaptation at the larger valve diameter. PU-PDMS exhibited greater permanent deformation compared to PCU and was selected to fabricate the valved conduits. The devices were dilated from 22 to 24.8 mm in diameter, while hydrodynamic testing showed persistence of competence with excellent valve function. The computational model showed good agreement with the experiments.
Conclusions: A PU-PDMS-based biostable valved conduit showed excellent hydrodynamic performance before and after a permanent balloon dilation. This proof of concept provides motivation for further development of a balloon-expandable device to replace valves in children and avoid reoperations.
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