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OBJECTIVES Neointimal hyperplasia might affect systemic-to-pulmonary shunt failure in infants with complex cyanotic congenital heart disease. The aim of this study was to elucidate histopathologic changes of polytetrafluorethylene shunts and to determine whether increased neointimal formation is associated with early interventions comprising balloon dilatation, stent implantation and shunt revision. Further, we intended to identify clinical factors associated with increased neointimal proliferation. METHODS Removed shunts were processed for histopathological analysis. Slides were stained with Hematoxylin/Eosin and Richardson. Immunohistochemistry was performed with anti-alpha-smooth muscle-actin and anti-CD68. Non-parametric analysis and univariable regressions were performed to identify clinical factors associated with neointimal hyperplasia and shunt stenosis. RESULTS Fifty-seven shunts (39 modified Blalock-Taussig anastomosis, 8 right-ventricle to pulmonary-artery anastomosis, 10 central shunts) were analyzed. Area of neointimal proliferation within the shunt was in median 0.75 mm2 [Interquartile range, 0.3 –1.57 mm2] and relative shunt stenosis in median 16.7% [Interquartile range, 6.7–30.8%]. Neointimal hyperplasia and shunt stenosis correlated with each other and were significantly greater in the group that required early interventions and shunt revision. Univariable linear regression identified smaller shunt size and lower acetylsalicylic acid dosage as factors to be associated with greater neointimal proliferation and shunt stenosis. CONCLUSIONS In infants with complex cyanotic congenital heart disease, neointimal hyperplasia in systemic-to-pulmonary shunts is associated with early interventions comprising balloon dilatation, stent implantation and shunt revision. Smaller shunt size and lower aspirin dosage are associated with increased neointimal proliferation.

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