Early Biological Reactions to a Novel Hybrid Knit Fabric Inducing Autologous Tissue Ingrowth Implanted in a Small Infant

Patch augmentation of the right ventricular outflow tract (RVOT) is frequently required in pediatric patients with stenosis or atresia affecting the right ventricle-to-pulmonary artery continuity. However there have been no ideal patch materials for pediatric patients. A 1-month-old infant with pulmonary atresia with an intact ventricular septum underwent surgical pulmonary valvotomy and RVOT reconstruction using a novel hybrid wrap-knitted patch designed for autologous tissue ingrowth. Ten months postoperatively, for recurrent severe pulmonary valve stenosis, the patient underwent repeat RVOT reconstruction. Histological examination of the excised hybrid patch revealed that both surfaces were covered with regenerated tissue composed of smooth muscle cells, blood vessels, and collagen fibers. Transmission electron microscopy confirmed that the regenerated tissue contained feature mature fibroblasts and capillaries, demonstrating sufficient development of regenerated tissue. Histological findings of the hybrid wrap-knit fabric patch excised in redo surgery 10 months after the initial surgery showed potential macrophage-fibroblast interaction, promoting tissue remodeling in the new fabric.