A Transcatheter Pulmonary Valve System for the Growing Hearts of Young Children

About This Grant

PROJECT SUMMARY/ABSTRACT Congenital heart defects (CHDs) occur in ~1% of births in the U.S. and Europe. Owing to improved medical and surgical care, it is estimated that nowadays 83% of babies born with CHD in the U.S. survive infancy. It is currently estimated that at least 1 million children are living with a CHD in the U.S. Most of these patients are born with some degree of right ventricular outflow tract (RVOT) abnormalities that at some point require pulmonary valve replacement to mitigate the detrimental effects of pulmonary valve regurgitation (PVR) on the right ventricle (RV). To address PVR, transcatheter pulmonary valve replacement (TPVR) is currently performed for these patients. Current TPVR systems are limited by size constraints that preclude their use in very small patients. Though, evidence supports the benefits of earlier intervention—even through surgical approaches—before the onset of symptoms, as this strategy can help preserve RV function and improve long-term outcomes. However, neither current TPVR devices nor surgically implanted valves can accommodate somatic growth, necessitating repeat interventions as children mature. This limitation underscores the critical need for next-generation valve technologies capable of expanding with the patient and reducing the lifetime burden of reintervention. Supported by an R21 award, we have developed the IRIS Valve—a growth-accommodating, origami-inspired TPVR system deliverable through a 12-Fr sheath for children as small as 8 kg. Designed to expand from 12 to 20 mm via balloon dilation, the valve maintains full leaflet coaptation across sizes and is constructed from three thin porcine pericardial leaflets on a stainless-steel stent with an ePTFE skirt. We have successfully implanted the IRIS Valve in the pulmonary position of eight Yucatan piglets for long-term (6-month) studies, with fluoroscopic and echocardiographic assessments confirming proper placement and function without regurgitation. This study will assess the safety and feasibility of the IRIS Valve in 36 gender-balanced Yucatan piglets over 12 months. Because Yucatan piglets reach near-adult heart size within a year—mirroring the human transition from infancy to late adolescence—this model effectively captures the challenges of pediatric growth.18 We aim to investigate two main hypotheses: (1) tendencies toward structural valve deterioration (SVD) in IRIS Valve's thin porcine pericardial leaflets implanted at the pulmonary position, and (2) the IRIS Valve's effectiveness in maintaining a low-pressure gradient and preventing regurgitation over a 12-month period.