Three-Dimensionally Printed Silicone Pulmonary Valves: A Promising First Step Toward Patient-Specific Valves and Clinical Translation

Pulmonary valve disease requiring prosthetic replacement-most commonly after repair of tetralogy of Fallot or other right ventricular outflow tract anomalies-remains a persistent challenge in congenital and structural heart disease.Both principal replacement options, mechanical valves and tissue-derived bioprostheses, have well-recognized limitations: mechanical prostheses require lifelong anticoagulation, whereas bioprosthetic valves are susceptible to early calcification and structural valve deterioration.Neither option accommodates pediatric growth, making repeated surgical or transcatheter reinterventions an expected part of treatment.Efforts to address this unmet need have sustained interest in polymeric valve platforms and valve platforms produced using 3-dimensional (3D) printing as a potential third approach.1,2 In this issue of the Journal of Cardiovascular Intervention, Lee et al. 3 report a preclinical feasibility study of a 3D-printed, silicone-based pulmonary valve prosthesis.The authors first printed a trileaflet mold using digital light processing (DLP), a vat-photopolymerization technique in which a projected ultraviolet image cures liquid resin layer by layer.They then formed the functional leaflets on this mold by applying a custom sequence of 25 silicone dispersion coatings: a "10 + 10 + 5" protocol comprising base, reinforcement, and finishing layers.This hybrid strategy combined an additively manufactured scaffold with manual multistage silicone coating, allowing leaflet thickness to be adjusted to 0.45-0.55mm, approximating that of native porcine leaflets.It also incorporated structurally informed features: thickened leaflet edges to reduce stress concentration at the coaptation line, a helical, propeller-like leaflet twist, and leaflet tips anchored to the stent frame to resist eversion under diastolic back-pressure.Bench testing evaluated hydrodynamic performance against the International Organization for Standardization (ISO) 5840-3:2013 criteria for effective orifice area, transvalvular pressure gradient, and regurgitant fraction.At both normotensive and hypertensive test pressures, the prototype achieved an effective orifice area exceeding the required 1.70 cm 2 threshold, a mean transvalvular pressure gradient of 14.1-16.4mmHg (overall mean, 15.05 ± 1.01 mmHg), and a regurgitant fraction below the 20% acceptance ceiling.In WST-1 cytotoxicity testing using RAW 264.7 macrophages, cell viability exceeded the 70% non-cytotoxicity threshold specified in ISO 10993-5 at both tested extract concentrations.