In vivo hemodynamic, histologic, and antimineralization characteristics of the mosaic bioprosthesis

Background. Performance of bioprosthetic valves is limited by tissue degeneration due to calcification with reduced performance and longevity. The Mosaic bioprosthetic valve (Medtronic Heart Valves, Inc, Minneapolis, MN) combines zero pressure fixation, antimineralization properties of alpha -amino oleic acid (AOA), and a proven stent design. We tested the hypothesis that AOA treatment of Mosaic valves improves hemodynamics, antimineralization properties, and survival in a chronic ovine model. Methods. Mitral valves were implanted in juvenile sheep with Mosaic valves with AOA treatment (n = 8) or without AOA treatment (non-AOA, n = 8), or Hancock I (HAN, n = 4) tissue valves, and explanted at 20 postoperative weeks. Results. Survival was equivalent in AOA and non-AOA (140 +/- 0.4 and 129 +/- 30 days): but was significantly less in HAN (82 +/- 35). Leaflet calcium (mu gCa/mg tissue) was less in AOA (9.6 +/- 13.9; p < 0.05 versus non-AOA and HAN) than non-AOA (96.3 +/- 63.8) and HAN (130.8 +/- 43.2). Explant valve orifice area (cm(2)) was significantly preserved in the AOA group compared with the non-AOA group (1.5 +/- 0.7 vs 0.8 +/- 0.3; p < 0.05 versus non-AOA and HAN). Conclusions. We conclude that AOA treatment of Mosaic valves reduces leaflet calcification and valve gradient in juvenile sheep, and that the Mosaic design and fixation features may offer survival advantages that must be confirmed in extended trials. (Ann Thorac Surg 2001;71:92-9) O 2001 by The Society of Thoracic Surgeons