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

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.

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 XPV and 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 XPV and H were assessed by transthoracic echocardiography.

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.

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.