| Objective: This research compares singly tanning bovine pericardial valves by amylic aldehyde with compound tanning with 1% cation fat. It studies the mechanism of tanning method of biological material on the molecular level through the test of stabilization, state dynamic, state tension and bent resistance. And it makes the evaluation of the characteristics of bovine pericardial biological material by compound tanning with 1% cation fat and clinical effects of bovine pericardial biovalve.Materials and Methods: First, pre-tan the strictly handled bovine pericardial tissue with 0.3% amylic aldehyde. Then, fatify it with 1% cation fat. And, tan it with 0.1% chromium trioxide. Last, refatify it with the sterile glycerol. Compare the content of calcium in the bovine pericardial material by compound tanning with 1% cation fat with singly tanning by amylic aldehyde. Make tests ofhistology, ultrastructure and mechanical tension resistance. Determine carboxyl content with Fourier infrared spectrum instrument. Test the bovine pericardial biovalve with redo imitated accelerated weariness experiment platform.Results: Cation fat infuses the bovine pericardial tissue and chromium ion evenly permeates the collagenous cells, in case rapid chromify after chromium tanning. And make the chromium ion combine with carboxyl of the biological tissue in case of calcification.Chromium ion combines with the collagenous molecule of the biological tissue, making the tissue fully and evenly chromify, and enhancing the tissue's strength. Refatify it with the sterile glycerol keeps the tanned biological tissue from fading tanning. It is good to the growing of autogenous endocardiac cells and keep them from calcification.The content of calcium in the bovine pericardial biological material by compound tanning with 1% cation fat is lower, with (2.87±0.37)μ g/mg in the compound tanning, while (9.82±4.47) μ g/mg in the singly tanning with amylic aldehyde. There is a significant difference between them ( P <0.05). Of the former, thickness of biovalve leaflet is 0.44±0.13mm, the bovine pericardial biological material is most soft when the contracted temperature is86-90℃, tension resistance is 19.9-25.9N/ mm~2, bent resistance is 92.3-112.7N/mm~2, extending rate is 43.4%-46.0%. As regards the latter, thickness of biovalve leaflet is 0.44 ±0.13mm, contracted temperature is 89-100℃, tension resistance is 10.4-16.5 N /mm~2, bent resistance 69.5-75.0 N/mm~2, extending rate is 38.1%-42.3%. Fourier infrared spectrum chart shows that carboxyl peak reduces obviously in the compound tanning, while biological material by singly tanning with amylic aldehyde still has rather a lot of carboxyls. Redo imitated accelerated weariness test shows 3,888 × 10~11 cycles in the bovine pericardial valve. By estimation, the biovalves will last for about ten years. Bovine pericardial valve by compound tanning with 1% cation fat still has firm structure under electron microscope in ten years. The collagenous fiber structure of the biological tissue arranges compactly and neatly, and the cell structure is intact. And calcification is not obvious. The bovine pericardial valve by singly tanning with amylic aldehyde failed in eight years after operation, and serious calcification can be seen under electron microscope. Clinical re-operation finds that the biovalves by compound tanning have no calcification and tearing in ten years.Conclusion: The biological material by compound tanningwith 1% cation fat overcomes the shortcoming of becoming hard and fragile and the calcification as a result of rapid chromify due to the simple tanning with amylic aldehyde. After the inaterial is fatified with 1% cation fat, it not only makes chromium ion fully permeate the cells and combine with carboxyl but also increases together with the collagenous molecule the firmness and softness of the biological tissue, and keeps it from calcification. Therefore, the biovalve's life span is longer. This method has high scholarly and practical value.
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