In Vivo Comparative Study of Calcification in Diepoxy- and Glutaraldehyde-Treated Bovine Pericardial Conduits for RVOT Reconstruction

Background/Objectives: Bovine pericardial valve conduits (PVCs) are commonly used for right ventricular outflow tract reconstruction in both pediatric and adult patients. Calcification, particularly prevalent in children and young adults, is a leading cause of conduit failure and is affected by the chemical composition of the treated biomaterials. In this study, we aimed to compare the structural changes in diepoxy-treated (DE-PVCs) and glutaraldehyde-treated PVCs (GA-PVCs) and to identify factors contributing to tissue mineralization in a large animal model. Methods: Pulmonary artery replacement was performed in minipigs (33–88 kg) using twelve DE-PVCs and four GA-PVCs. After six months, the animals were euthanized, and the explanted PVCs underwent macroscopic and microscopic examination. Results: Large calcium deposits formed along conduit joining suture (CJS) lines in all PVCs, regardless of the cross-linking agent. Mineral clusters surrounded the multifilament braided thread, and its fibers were encrusted with hydroxyapatite crystals. In DE-PVCs, no mineralization occurred outside the suture lines, and they showed successful integration and graft vitalization with a uniform neointima and well-developed endothelial monolayer. GA-PVCs developed a rigid external capsule, foci of collagen fiber calcification within the walls, and neointimal hyperplasia with limited endothelial coverage. Conclusions: In PVCs, calcification predominantly occurs along the CJS lines, where the multifilament suture acts as a nucleation site for hydroxyapatite crystals. DE treatment prevents collagen mineralization, unlike GA, and offers better integration, reduced neointimal hyperplasia, and a well-developed endothelial layer. These findings suggest that DE-PVCs may be a superior option for pediatric cardiac surgery by reducing calcification and improving conduit durability. Overall, the results will help optimize PVC manufacturing strategies to lower the risk of conduit failure.