PROJECT SUMMARY In pediatric cardiovascular surgery, no commercially available vascular conduit is capable of growing with the patient following implantation. This inability to grow with the patient is particularly relevant for newborns and young children because additional surgeries are required to replace the implanted conduit. In order to address this issue, PECA Labs has developed a novel cardiovascular conduit that can be expanded with a minimally invasive balloon catheter. This technology has been achieved by altering the properties of expanded Polytetrafluoroethylene (ePTFE) through a propriety manufacturing process. A prototype of PECA?s expandable conduit has successfully been developed, produced, and validated through in vitro and ex vivo preliminary studies. The overall goal of the proposed research is to gain important knowledge of the biocompatibility and in- vivo performance of this expandable ePTFE conduit (EEC). Benchtop ex-vivo testing has illustrated the functionality of the proposed EEC: resisting spontaneous expansion at normal pressures, but capable of expanding by dilation with a standard balloon catheter. Expansion to well over three times the original diameter has been demonstrated without compromising the mechanical strength. The first aim of this study is to compare the biocompatibility of pre- and post-expansion EEC to currently available and commonly used ePTFE vascular grafts. Biocompatibility testing will consist of cytotoxicity, system toxicity, hemolysis, sensitization, irritation, implantation, and USP plastics analysis. Chemical analysis of the conduit will also by conducted by using polar and non-polar solvent extractable and leachable testing with GC- MS, LC-MS, ICP-MS, and UV-Vis spectrophotometry. It is expected that the results of these tests will show that the EEC is biocompatible. The second aim is to compare the in vivo functionality and biocompatibility of PECA?s EEC with commercially available ePTFE vascular grafts in a large animal model. We will demonstrate controlled expansion of the EEC with a minimally invasive procedure. It is expected that the biocompatibility will be acceptable, and successful EEC expansion will be safely achieved. Successful realization of the aims in this proposal will allow for Phase II studies to complete longer-term preclinical research and any remaining regulatory requirements in order for this novel product to become available for newborns and growing children with congenital heart disease. Without the need for repeat surgeries to upsize conduits, thousands of children with various forms of heart disease would directly benefit from this technology, and there would also be a reduction in the burden on the healthcare system.