PEDS9: Acute Porcine Studies Evaluating a Growth Adaptive Pediatric Heart Valve

Valve defects are the most common congenital heart defect, often requiring several surgeries from infancy for survival. There is no suitable solution specifically for infants with valve diameters <15mm. We aim to create a pediatric heart valve (PHV) that will expand while maintaining function over a doubling in valve diameter (7-14 mm) as the patient grows to be 5-6 years old. Over the past year, we have further developed our PHV and tested in two piglets for acute implantation and performance studies. In vivo and ex vivo measurements of juvenile porcine heart tissue was conducted to inform stent design. Using nonlinear finite element analysis, we modeled the performance of the stent design to reach a target force profile. The stents were laser cut in Nitinol, key dimensions were measured, and radial force testing was conducted to verify the designs performance. We sutured a femoral valve to the inside of the stents and avoided the use of a tissue skirt to reduce instances of thrombosis. The assembled valves were implanted into two Yucatan piglets (5.0-5.5 kg, PA Diameter ~8.5mm). Anatomical measurements of the pulmonary artery (PA) and pulmonary valve (PV) were taken using epicardial echocardiography and calipers. The valve and stents were sutured together successfully and showed to be functional via bench testing. The stent’s final maximum radial force was higher than predicted but still functional within an acute animal study. In the first study, a compressed stent was inserted with 4 sutures. We found the suturing and placement between the annulus and PA to be inadequate. In the second study, a stent in the expanded state was inserted more distally into the PA with 8 sutures. Implantation was complicated by the expanded state and the stent not conforming to the curved PA geometry. Despite the challenges, the valve maintained its function. Additional work is underway to optimize implantation strategy and PHV function for survival studies. Sponsor Acknowledgment Statement: This work was supported by the DoD USAMRAA through the Pediatric Heart Valve under Award No. W81XWH-20-1-0295, “Growth-Adaptive Pediatric Heart Valves: Addressing a Critical Unmet Need for Infants and Young Children That Saves Lives and Reduces Surgeries”. Opinions, interpretations, conclusions and recommendations are those of the author and are not necessarily endorsed by the DoD USAMRAA.