Bianco R W, Phillips R, Mrachek J, Witson J
University of Minnesota, Minneapolis, USA.
J Heart Valve Dis. 1996 May;5(3):317-22.
In an attempt to overcome the problem of calcification of bioprostheses, a novel bovine pericardial tissue valve preserved with a non-aldehyde, dye mediated photo-oxidation process (PhotoFixTM) developed by CarboMedics, Inc. The device was evaluated by implantation in the mitral position of juvenile sheep with a mean age of 3.5 months.
Thirteen valves were evaluated; six experimental valves with photo-oxidized tissue, five identically designed valves with glutaraldehyde-fixed tissue, and two Carpentier-Edwards pericardial valves as controls.
Four of the six animals in the photo-oxidized group were free of calcification when electively sacrificed at 152 days, 152 days, one year and 1.5 years respectively. One animal was electively sacrificed at 98 days. Pathologic findings indicated minimal calcification of the valve due to uneven stress distribution from two bent stent posts that most likely occurred during surgical implantation, but the device was still functional. The sixth animal with photo-oxidized tissue died at 131 days due to massive calcification of a single leaflet. There was no pathologic evidence of infection. Explants at five months from additional and still continuing sheep studies per FDA guidelines have not reproduced single leaflet calcification in over forty explanted valves with photo-oxidized tissue. The glutaraldehyde-fixed valves all exhibited some calcification at explant; two of these animals died early due to the mineralization. Both control animals with Carpentier-Edwards valves died early from mitral stenosis due to extensive device calcification.
The fact that four of six valves with photo-oxidized tissue remained free of any signs of calcification for up to 1.5 years, while none of the other valves did, suggests that photo-oxidation is a promising method of preserving and fixing tissue for use in bioprostheses. These results suggest that photo-oxidized bioprosthetic valves may be clinically valuable and warrant further study.
为解决生物假体钙化问题，研发了一种新型牛心包组织瓣膜，采用由CarboMedics公司开发的非醛类、染料介导的光氧化工艺（PhotoFixTM）进行保存。通过将该装置植入平均年龄为3.5个月的幼年绵羊二尖瓣位置进行评估。
评估了13个瓣膜；6个采用光氧化组织的实验瓣膜，5个设计相同的采用戊二醛固定组织的瓣膜，以及2个Carpentier-Edwards心包瓣膜作为对照。
光氧化组的6只动物中，分别在152天、152天、1年和1.5年时选择性处死的4只动物未出现钙化。1只动物在98天时被选择性处死。病理结果表明，由于手术植入过程中两个弯曲的支架柱应力分布不均，瓣膜出现了轻微钙化，但该装置仍能正常工作。第6只采用光氧化组织的动物在131天时因单个瓣叶大量钙化死亡。没有感染的病理证据。根据美国食品药品监督管理局（FDA）指南，对另外仍在进行的绵羊研究中5个月时取出的样本进行检查，超过40个采用光氧化组织的取出瓣膜未再现单个瓣叶钙化情况。戊二醛固定的瓣膜在取出时均表现出一定程度的钙化；其中2只动物因矿化过早死亡。两个使用Carpentier-Edwards瓣膜的对照动物均因装置广泛钙化导致二尖瓣狭窄而过早死亡。
6个采用光氧化组织的瓣膜中有4个在长达1.5年的时间内未出现任何钙化迹象，而其他瓣膜均未出现这种情况，这表明光氧化是一种用于保存和固定生物假体组织的有前景的方法。这些结果表明，光氧化生物假体瓣膜可能具有临床价值，值得进一步研究。
