机械应力对牛心包瓣原发性损坏的影响  

Effect of Mechanical Stresses on Primary Tissue Failure of Bovine Pericardial Valve

作　　者：张祖仁[1] 王一山[1] 冯卓荣[1] 

机构地区：[1]上海第二医科大学附属仁济医院胸外科,上海200011

出　　处：《生物医学工程学杂志》1992年第3期217-221,共5页Journal of Biomedical Engineering

摘　　要：引起牛心包瓣原发性损坏的生理学和病理学因素与机械学因素同等重要。从我院再次手术中收集到的22只失效瓣膜来看,在瓣架尖端区和侧边区的损坏发生率分别占30.3％和36％,撕裂、磨损和钙化的发生率分别占25.8％、18％和31.6％。牛心包片的弯曲试验和牛心包瓣的显微镜观察表明,由于经戊二醛处理的牛心包片的拉伸弹性模量是压缩模量的25倍,因此当牛心包片弯曲变形时,弯曲内侧必然出现挤压屈服,并逐渐发展到楔状挤压。牛心包瓣临床失效的形式及其分布提示,瓣叶损坏主要是由于瓣叶在启闭活动过程中的这种弯曲挤压引起的。因此在改进牛心包瓣时,应考虑机械应力,特别是弯曲变形的应力对瓣膜损坏的影响。The bovine pericardial valves(BPVs) usually do not need anticoagulant therapy after implantation, but they are progessively failured in the heart and require reimplantation 5-10 years after their initial implantation. From February 1979 to January 1990,251 BPVS were implanted in 9.44 patients at Ren Ji Hospital, Shanghai Second Medical University. A total of two aortic and 20 mitral valves with primary tissue failure(PTF) were explanted at reoperation. Along with coexistent pathologic findings, calcification and tearing were the main causes of PTF of BPVs. Thc majority of sutures or stitch sites in valve were involved by varying degrees of wearing in surrounding cusp material, manifested by swelling and breakdown of cusp tissue with or without varyingc degree of calcification or tearing. Most of the valves had one of mere tearings, Collagen damage caused by mechanical stresses could be the precursor of calcification and tearing. On the basis of mechanical test, the tensileelastic modulus of glutaraldehyde treated bovine pericardium was be about 25 times greater than the compressive modulus. We observed severe compressive buckling in the samples taken from BPV. Examinations of the bend of bovine pericardium and the leaflet action of BPV have showed that the areas of sharp bending curvature were near the attachment of the leaflets to the stents, which correlated well with sites of leaflte tearing or calcification. The increased stresses resulted from the increased bending stiffness would ultimately lead to the observed leaflet tearing, calcification and eventual failure of the BPVs. The experiments indicated that collagen fiber disruption resulting from cyclic leaflet bending would be the main factor determinant of long-term durability of BPVs. We believe that the PTF is related to compressive buckling of the glutaraldehyde-treated BPVs. This analysis of the effect of mechanical stresses on PTF of BPVs enable us to help to improve the design of the BPVs and reduce the risk of potential PTF in patients, with valve r

关 键 词：牛心包瓣 原发性损坏 瓣叶 

分 类 号：R654.2[医药卫生—外科学]