A common feature of congenital heart disease is the presence of right ventricular outflow tract (RVOT) obstruction that can range from mild to severe and can lead to atresia of the pulmonary valve, in extreme conditions. RVOT abnormalities can frequently be corrected surgically or via interventional means. However, most of these patients will ultimately develop pulmonary valve insufficiency and eventual right ventricular dilation, which will require a pulmonary valve replacement at some point in their life to mitigate the detrimental effects of pulmonary valve regurgitation (PVR) on the right ventricle (RV). The evolution from the studies done by Philip Bonhoeffer to implant a pulmonary valve via transcatheter means, have provided a bedrock for transcatheter pulmonary valve replacement (TPVR). Yet, several areas of unmet need for a demographic of patients still exist. Here, we discuss the clinical unmet needs in children under 20 Kg and expand the use of hybrid and other TPVR approaches along with the current indications and contraindications for pulmonary valve replacement. The constraints and limitations from commercially available pulmonary valves will be discussed from a clinical standpoint. Finally, we explore the use of hybrid and periventricular delivery of transcatheter pulmonary valves in younger patients.

Introduction: It is estimated that at least 1 million children are living with a congenital heart defect (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). Due to their size, available solutions, e.g., the Melody™ valve (Medtronic Inc., Minneapolis, MN) cannot be implanted in small children under 20 Kg. Those must wait until they grow to a suitable weight to receive the valve, which may lead to RV dysfunction. Hypothesis: To mitiagte the detrminental effects to the RV, the IRIS™ valve is implantable at 12 mm with a 12-Fr delivery catheter. As the valve annulus grows, the valve would be balloon expanded up to 20 mm. Methods: The IRIS™ valve has been designed according to origami concepts such that its three leaflets would retain a fully-coapted form as it is expanded to a larger size. Here we report our methods and results of implantation in 9-17Kg Yucatan pigs. Results: The IRIS™ valve is made of thin porcine pericardial leaflets sewn into a laser-cut stainless-steel stent. The stented valve is covered with an ePTFE skirt to mitigate paravalvular leak. The IRIS™ valve is fully crimped over a 12-Fr delivery catheter for transfemoral implantation. We have successfully implanted the valve at the native pulmonary valve position with minimal regurgitation in three pigs ranging from 9 to 17kg with varying pulmonary annulus sizes. Conclusions: The IRIS™ transcatheter pulmonary valve has been successfully developed according to proprietary origami concepts. Using the 12Fr delivery catheter, the smallest delivery profile reported, we successfully implanted the IRIS™ valve within the pulmonary annulus of mini pigs with encouraging results.