A novel restorative pulmonary valved conduit in a chronic sheep model: Mid-term hemodynamic function and histologic assessment

Objective: To evaluate the safety and the short-term function of a novel pulmonary valved conduit (Xeltis Pulmonary Valved Conduit; XPV) up to 12 months in a sheep model. Methods: XPV and Hancock bioprosthetic valved conduits (H, used as control) were implanted in adult sheep in the pulmonary artery position. Animals were killed at 2 months (n = 6 XPV), 6 months (n = 6 XPVand n = 3 H), and 12 months (n = 6 XPV) and examined histologically. During follow-up, function of the device as well as diameter of both XPVand H were assessed by transthoracic echocardiography. Results: Of 18 animals that received an XPV, 15 survived until they were killed; 3 animals that received H survived the planned observational interval. XPV showed mild neointimal thickening and degradation beginning at 2 months with an ongoing process until 12 months. Only 1 of the 18 animals with XPV had significant calcification at 6 months. Pathologic specimen did not show any significant narrowing of the conduit whereas neointimal thickness showed a peak at 6 months. Inflammatory process reached a maximum at 6 months and the degradation process at 12 months. Gel permeation chromatography analysis showed molecular weight loss beginning at 2 months with a peak at 12 months for the conduit with slower absorption for the leaflets. The wall of the H conduits showed more neointimal thickening, narrowing, and calcification compared with XPV, but the leaflets demonstrated minimal changes. Conclusions: Both conduits demonstrated an acceptable safety and functionality. Significant calcification was rarely observed in the XPV, whereas the H developed more neointimal thickness with calcification of the porcine aortic root portion of the wall.