Mirzaie M, Meyer T, Schwartz P, Dalichau H
Department of Thoracic, Heart and Vascular Surgery, University of Göttingen, Germany.
J Heart Valve Dis. 2000 Jul;9(4):576-82.
In recent years a number of fixation and anti-calcification methods have been developed, but little is yet known about the calcification process of biological valves. The aims of this study were to: (i) perform a systematic ultrastructural investigation on various biological valves; and (ii) determine the extent of calcification of these valves in a subcutaneous rat model.
The following porcine aortic prostheses were investigated: Toronto-SPV, Intact, Freestyle, Mosaic and Hancock-II. Samples taken from the valve leaflets, and in the case of the Freestyle and Toronto-SPV valves also from the aortic wall, were examined ultrastructurally using scanning and transmission electron microscopy. Other samples were implanted subcutaneously in Wistar rats for 12 weeks. The calcium content of the samples was measured using atomic absorption spectrophotometry.
All valves examined showed a considerable loss of the endothelial cover. Significant changes in valve ultrastructure were also detected. With regard to calcium content, two valve groups could be distinguished (p <0.05): (i) those with high calcium content, e.g. Toronto-SPV and Intact (>40 mg/g dry tissue); and (ii) those with low calcium content, e.g. Mosaic, Freestyle and Hancock-II (<5 mg/g).
Fixation methods have pronounced effects on the ultrastructural integrity of bioprostheses. The degenerative calcification of bioprostheses can be effectively inhibited by glutaraldehyde-free fixation and anti-calcification treatments.
近年来，已开发出多种固定和抗钙化方法，但对于生物瓣膜的钙化过程仍知之甚少。本研究的目的是：（i）对各种生物瓣膜进行系统的超微结构研究；（ii）在大鼠皮下模型中确定这些瓣膜的钙化程度。
研究了以下猪主动脉假体：多伦多SPV、完整型、自由型、镶嵌型和汉考克-II型。从瓣膜小叶取样，对于自由型和多伦多SPV瓣膜，还从主动脉壁取样，使用扫描和透射电子显微镜进行超微结构检查。其他样品皮下植入Wistar大鼠12周。使用原子吸收分光光度法测量样品中的钙含量。
所有检查的瓣膜均显示内皮覆盖物大量缺失。还检测到瓣膜超微结构的显著变化。关于钙含量，可以区分出两组瓣膜（p<0.05）：（i）钙含量高的瓣膜，例如多伦多SPV和完整型（>40mg/g干组织）；（ii）钙含量低的瓣膜，例如镶嵌型、自由型和汉考克-II型（<5mg/g）。
固定方法对生物假体的超微结构完整性有显著影响。无戊二醛固定和抗钙化处理可有效抑制生物假体的退行性钙化。
