Vesely I, Mako W J
Department of Biomedical Engineering, Lerner Research Institute, The Cleveland Clinic Foundation, Ohio 44195, USA.
J Heart Valve Dis. 1998 Jan;7(1):34-9.
Compressive buckling at sites of sharp leaflet flexure has been implicated as a mechanism of failure in porcine xenografts. The potential for such buckling to cause damage in new-generation pericardial valves, however, has not been examined.
Clinical-grade bovine pericardium fixed in 0.625% glutaraldehyde was cut into 5 mm-wide strips. Fresh porcine aortic valve leaflets were fixed flat in 0.625% glutaraldehyde and 5 mm-wide circumferential strips were cut. These tissues were bent to various curvatures, held bent with sutures, histologically processed, and sectioned and stained with hematoxylin and eosin. Images of the specimens were acquired by computer and the depth of compressive buckling, thickness of the specimen, and local curvature were measured.
Porcine tissue showed a progressive increase in depth of buckling as both thickness and curvature increased, while bovine pericardium had minimal buckling at all curvatures. Porcine tissues buckled to a mean (+/- SEM) fractional depth of 0.23+/-0.012 while bovine pericardium buckled to only 0.09+/-0.006.
These data suggest that the internal fibrous structure of bovine pericardium may tolerate high bending curvatures better than porcine aortic valve leaflets when stiffened and cross-linked with glutaraldehyde. This may explain the apparently good durability of current generation pericardial valves.
尖锐瓣叶弯曲部位的压缩屈曲被认为是猪异种移植物失效的一种机制。然而，这种屈曲对新一代心包瓣膜造成损伤的可能性尚未得到研究。
将固定在0.625%戊二醛中的临床级牛心包切成5毫米宽的条带。将新鲜猪主动脉瓣叶平放在0.625%戊二醛中固定，然后切成5毫米宽的圆周条带。将这些组织弯曲到不同的曲率，用缝线固定弯曲状态，进行组织学处理，切片并用苏木精和伊红染色。通过计算机获取标本图像，并测量压缩屈曲深度、标本厚度和局部曲率。
随着厚度和曲率的增加，猪组织的屈曲深度逐渐增加，而牛心包在所有曲率下的屈曲都最小。猪组织的屈曲平均（±标准误）分数深度为0.23±0.012，而牛心包仅为0.09±0.006。
这些数据表明，当用戊二醛硬化和交联时，牛心包的内部纤维结构可能比猪主动脉瓣叶更能耐受高弯曲曲率。这可能解释了当前心包瓣膜明显良好的耐久性。
