ONSET AND PROGRESSION OF CALCIFICATION IN PORCINE AORTIC BIOPROSTHETIC VALVES IMPLANTED AS ORTHOTOPIC MITRAL-VALVE REPLACEMENTS IN JUVENILE SHEEP
ONSET AND PROGRESSION OF CALCIFICATION IN PORCINE AORTIC BIOPROSTHETIC VALVES IMPLANTED AS ORTHOTOPIC MITRAL-VALVE REPLACEMENTS IN JUVENILE SHEEP
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DOI：
10.1016/s0022-5223(94)70186-5
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发表时间：
1994-11-01
影响因子：
6
通讯作者：
LEVY, RJ
中科院分区：
文献类型：
--
作者：
SCHOEN, FJ;HIRSCH, D;LEVY, RJ
本研究的目的是描述植入羊体内的猪生物瓣膜矿化的发生和进展，并验证这种瓣膜模拟临床和其他实验模型中观察到的钙化的假设。Hancock I型猪主动脉生物瓣膜（Medtronic Heart Valve Division, Irvine, california）仅作为原位二叠瓣置换植入幼年羊，1 ~ 124天后取出，并进行如下分析：肉眼检查，x线摄影，光，透射，表面扫描电镜，吸收光谱分析钙。在瓣尖和邻近主动脉壁植入后，矿化随时间的延长而增加。切除瓣膜3 ~ 4个月后，平均尖钙化80 μ g/mg。然而，在特定的时间间隔内，瓣膜之间的钙化水平明显存在相当大的差异。几乎所有方面的形态学特征是相同的那些以前指出的临床移植和实验标本，无论是皮下和循环。特别是超微结构检查显示，最早的钙化沉积与失活的尖结缔组织细胞及其碎片有关。胶原蛋白钙化稀疏。表面扫描和透射电镜显示，在所有采样时间瓣膜上缺乏内皮细胞或血源性细胞。我们得出结论，将猪生物瓣膜植入羊的二尖瓣提供了一个有用的钙化模型，可以模拟临床和非循环模型中发生的形态学和病理生物学事件。然而，必须进行足够的标本复制，以克服瓣膜和采样点之间钙化的可变性。
The purpose of this study was to characterize the onset and progression of mineralization in porcine bioprosthetic valves implanted in sheep and to test the hypothesis that such valves simulate calcification that is observed clinically and in other experimental models. Hancock I porcine aortic bioprosthetic valves (Medtronic Heart Valve Division, Irvine, Calif.) mere implanted as orthotopic mitral valve replacements in juvenile sheep, retrieved after 1 to 124 days, and analyzed as follows: gross inspection, radiography, light, transmission, and surface scanning electron microscopy, and calcium analysis by absorption spectroscopy. Mineralization increased with ina easing time after implantation in both valve cusps and adjacent aortic wall. Mean cuspal calcification was 80 mu g/mg in valves removed after 3 to 4 months. Nevertheless, considerable variability among valves was apparent in the level of calcification noted at specific time intervals. Virtually all aspects of the morphologic characteristics were identical to those previously noted for clinical explants and experimental specimens, both subcutaneous and circulatory. In particular, ultrastructural examination revealed that the earliest calcific deposits were associated,vith devitalized cuspal connective tissue cells and their fragments. Collagen calcification was sparse. Both surface scanning and transmission electron microscopy indicated a lack of endothelial or blood-derived cells on the valves at all sampling times. We conclude that porcine bioprosthetic valves implanted as mitral valves in sheep provide a useful calcification model, simulating morphologic and pathobiologic events that occur clinically and in noncirculatory models. However, sufficient specimen replicates must be done to overcome variability in calcification among valves and sampling sites.