Mitigation of bioprosthetic heart valve degeneration through biocompatibility: in vitro versus spontaneous endothelialization

Background: Glutaraldehyde related cytotoxicity and transanastomotic ingrow th inhibition prevent the spontaneous endothelialization of bioprosthetic h eart valves. Tn order to evaluate the ability of improved biocompatibility to reduce tissue degeneration, conventionally fixed aortic root prostheses were both glutaraldehyde-detoxified and in vitro endothelialized. Methods: Entire aortic roots were fixed in 0.2% glutaraldehyde (GA) (control group) and either detoxified in acetic acid-buffered urazole (0.1 M) or detoxified and in vitro lined with cultured, autologous jugular vein endothelial cell s. The valved roots were inserted in the distal aortic arch of 15 juvenile Merino sheep for a period of 12 weeks. Upon explant, leaflets, sinuses and aortic wall of the prostheses were analysed by SEM to assess the surface en dothelium, histologically regarding tissue inflammation, and by atomic abso rption spectrophotometry to determine the content of tissue calcium. Result s: There was no endothelium on control grafts, except for a short anastomot ic pannus. The detoxified group showed an incomplete patchy endothelium on the aortic wall but hardly any on the leaflets, whereas, the in vitro lined group had aortic wall, sinuses and most of the leaflets confluently endoth elialized. Tissue inflammation was prominent in the control group and least expressed in the endothelialized group (p < 0.05). Detoxification signific antly reduced leaflet calcification. Tn the aortic wall, both detoxificatio n and endothelial lining were required to significantly mitigate calcificat ion. Conclusion: In the 12 week circulatory sheep model, the calcium mitiga ting effect of detoxification was more pronounced than that of in vitro end othelialization. Nevertheless, there was a distinct overall benefit if deto xification was combined with endothelialization. (C) 2001 Elsevier Science Ltd. All rights reserved.