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KMID : 0378020000430050015
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New Medical Journal
2000 Volume.43 No. 5 p.15 ~ p.23
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The Study of the Calcification of Experimental Animal Cardiac Valve as a Material of the Artificial Cardiac Prosthesis
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Abstract
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Bovine pericardium strips, porcine valve strips and canine valve strips, were treated with 0.625 % glutaraldehyde, subdermally implanted in rats, and then the weight and the amount of calcium were examined nine weeks later.
The results obtained from this study were as follows.
The bovine pericardial strips had 26.26% increase in weight after they had been implant-ed, and the proportion of calcium increased by 6.91 % as compared with that of original glu-taraldehyde treated pericardium. Thus, it was estimated that the calcification contributed 26.31 % to the weight gain. Histologically, bovine pericardium had shown no evidence of calcification before implantation, but the dense calcified deposits were noted in the bovine pericardial wall after implantation.
Electron microscopic examination showed that concentric electron dense calcified deposits were noted in the midst of the collagen fibers, and the linear calcified deposits were found throughout the entire pericardial tissue.
The implanted porcine valve strips had 23.56% increase in weight after implantation and the proportion of calcium was 6.82% higher than that of the original glutaraldehyde treated porcine valve. Thus, it is also estimated that the calcification brought about 28.94% of the weight gain.
It was shown that the preimplanted porcine valves had no evidence of calcification which was as histologically important as that in the bovine pericardial strips which were presented above, but it was revealed that after implantation the porcine valve had calcification in periph-eral zones. Electron microscopic examination also showed that the concentric electron-dense
calcified deposits were noted in the interstitium of the porcine heart valve and intracytoplas-mic concentric deposits containing spherical crystalloid core were noted as well.
Canine valve strips had 21.82% increase in weight after implantation and the proportion of calcium was 1.04% higher than that of the original glutaraldehyde treated canine cardiac valve. Thus, it is also estimated that the calcification brought about 4.7% of the weight gain.
Histologically, the canine cardiac valve had shown loose myxoidstroma and scattered fibroblast before implantation, and there was no identifiable calcification after implantation. Electron microscopic examination showed collagen bundles with speckled calcified gran-ules and various-sized calcified particles.
The authors conclude that the calcification of bioprosthesis could be regarded as the most important factor in developing a durable prosthetic heart valve. Electron microscopy showed that the process of the calcification primarily starts on the surface of collagen fib-rills and in the interfibrillar space.
The authors believe that this is a helpful fording in the effort to prevent valvular calcifica-tion after artificial valve replacement.
Further, the authors believe that the use canine cardiac valves as an artificial cardiac prosthesis will improve their durability.
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