Background

Limited mid-term durability of 12A/LX Mitroflow bioprosthesis has been reported. Aim of the study was to ascertain the pathologic substrates and possible mechanisms of structural valve deterioration in explants from animals and humans.

Methods

Nine aortic 12A/LX Mitroflow bioprostheses preserved in hypotonic solution and three aortic 12A/LX bioprostheses, preserved in isotonic solution, were explanted from juvenile sheep, mean time from implant 95.66 ± 36.04 days and 132.33 ± 28.88 days from implant respectively. One stented unimplanted 12A/LX Mitroflow preserved in isotonic colution before glutaraldeyde fixation served as control. Ten aortic 12A/LX Mitroflow bioprostheses were explanted from humans because of severe dysfunction: five children, (3 females and 2 males, mean age 14.19 ± 4.77 years, range 11-21), 26 ± 8.24 months from implant and 5 adults (4 females and 1 male, mean age 57.4 ± 19.85 years, range 31-72), 64.4 ± 26.94 months from implant. X-ray, histology, and transmission electron microscopy were carried out as well as spectroscopy for calcium (Ca++) and phosphorus (P) content in human explants.

Results

Explants, from both animals and humans, showed cusp folding and stiffness, with coarse calcific deposits at gross examination and X-ray. Severe collagen denaturation, plasma insudation and massive calcification, involving both collagen and cell debris, were observed microscopically. Mean Ca++ content of 183.27 ± 62.48 and P content of 94.35 ±33.76 mg/g dry weight was found in children and Ca++ content of 205.49 ± 2.23 and P content of 99.75 ± 0.11 mg/g dry weight in adults. Obstructive fibrous tissue overgrowth was detected in 6 human cases.

Conclusions

Collagen denaturation was observed in pericardial Mitroflow 12A/LX bioprosthesis with premature structural valve deterioration. Optimal collagen fixation and preservation as well as phospholipids reduction by removing cell debris, as employed in the novel CROWN PRT Mitroflow bioprosthesis, are expected to solve the flaw and achieve long-term durability.

中文翻译：

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Mitroflow 心包生物瓣膜 (12A/LX) 早期失败的病理

背景

据报道，12A/LX Mitroflow 生物假体的中期耐久性有限。该研究的目的是确定动物和人类外植体中瓣膜结构退化的病理基础和可能机制。

方法

从幼羊中取出保存在低渗溶液中的九个主动脉 12A/LX Mitroflow 生物假体和保存在等渗溶液中的三个主动脉 12A/LX 生物假体，从植入开始的平均时间分别为 95.66 ± 36.04 天和 132.33 ± 28.88 天。一个在戊二醛固定前保存在等渗溶液中的带支架未植入 12A/LX Mitroflow 作为对照。由于严重的功能障碍，10 个主动脉 12A/LX Mitroflow 生物假体从人体中取出：5 名儿童（3 名女性和 2 名男性，平均年龄 14.19 ± 4.77 岁，范围 11-21），植入后 26 ± 8.24 个月和 5 名成人（4女性和 1 名男性，平均年龄 57.4 ± 19.85 岁，范围 31-72)，植入后 64.4 ± 26.94 个月。X射线，组织学，

结果

来自动物和人类的外植体在肉眼检查和 X 射线检查中都显示出尖瓣折叠和僵硬，有粗大的钙化沉积物。在显微镜下观察到严重的胶原变性、血浆浸渍和大量钙化，涉及胶原蛋白和细胞碎片。儿童平均 Ca++ 含量为 183.27 ± 62.48，P 含量为 94.35 ±33.76 mg/g 干重，成人 Ca++ 含量为 205.49 ± 2.23，P 含量为 99.75 ± 0.11 mg/g/g 干重。在 6 个人类病例中检测到阻塞性纤维组织过度生长。

结论

在心包 Mitroflow 12A/LX 生物假体中观察到胶原变性，瓣膜结构过早退化。新型 CROWN PRT Mitroflow 生物假体采用的最佳胶原蛋白固定和保存以及通过去除细胞碎片来减少磷脂，有望解决该缺陷并实现长期耐用性。