Vesely I, Boughner D, Song T
John P. Robarts Research Institute, London, Ont, Canada.
Ann Thorac Surg. 1988 Sep;46(3):302-8. doi: 10.1016/s0003-4975(10)65930-9.
Current reports indicate that collagen fiber disruption resulting from cyclic leaflet bending is a factor determining long-term durability of bioprosthetic heart valves. Examination of the opening characteristics of porcine xenografts has shown two areas of high bending curvature that correlate well with sites of leaflet tearing. These are at the free edge and near the attachment of the leaflets to the aortic root. To determine the potential effects of sharp bends in leaflet material, we examined 15 strips each of fresh and glutaraldehyde-treated porcine aortic valve tissue. Leaflet strips were bent to curvatures of 0.18 mm-1 to 6.67 mm-1, histologically processed, sectioned, and examined under a light microscope. We observed severe compressive buckling in the samples taken from bioprosthetic valves but little in the fresh-tissue samples. At physiological curvatures (less than 0.28 mm-1), no buckling occurred in the fresh tissue; at high bending curvatures (2.0 mm-1), the depth of buckling observed in the treated tissue was 100% greater than that in the fresh. We believe that porcine xenograft failure is related to compressive buckling of the aldehyde-treated tissue and is mediated by the systematic breaking of collagen fibers at the site of buckling. We suggest that alternative valve designs and preservation techniques be employed to prevent such abnormal leaflet deformations.
目前的报告表明，瓣叶周期性弯曲导致的胶原纤维破坏是决定生物人工心脏瓣膜长期耐久性的一个因素。对猪异种移植物开放特性的检查显示，有两个高弯曲曲率区域与瓣叶撕裂部位密切相关。这些区域位于自由边缘和瓣叶与主动脉根部连接处附近。为了确定瓣叶材料中急剧弯曲的潜在影响，我们检查了15条新鲜的和经戊二醛处理的猪主动脉瓣组织。将瓣叶条弯曲至曲率为0.18 mm-1至6.67 mm-1，进行组织学处理、切片，并在光学显微镜下检查。我们观察到，取自生物人工瓣膜的样本中出现了严重的压缩屈曲，而新鲜组织样本中则很少出现。在生理曲率（小于0.28 mm-1）下，新鲜组织中未发生屈曲；在高弯曲曲率（2.0 mm-1）下，处理过的组织中观察到的屈曲深度比新鲜组织中的大100%。我们认为，猪异种移植物的失效与醛处理组织的压缩屈曲有关，并且是由屈曲部位胶原纤维的系统性断裂介导的。我们建议采用替代的瓣膜设计和保存技术来防止这种异常的瓣叶变形。
