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KMID : 0880420010020020075
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Korean Journal of Radiology
2001 Volume.2 No. 2 p.75 ~ p.79
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Evaluation of the Biodurability of Polyurethane-Covered Stent Using a Flow Phantom
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Sung Gwon Kang/Dong Hyun Kim
Sung Gwon Kang/Jung Ryul Choi/Ju Nam Byun/Young Chul Kim/Young Moo Ahn
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Abstract
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Objective: To evaluate the biodurability of the covering material in retrievable metallic stents covered with polycarbonate polyurethane.
Materials and methods: Using a peristaltic pump at a constant rate of 1 ml/min, bile was recirculated from a reservoir through a long tube containing four stents. Each of these was removed from the system every two weeks and a radial tensile strength test and scanning electron microscopy (SEM) were performed. Each stent, removed at 2, 4, 6 and 8 weeks, was compared with a control stent not exposed to bile juice.
Results: Gross examination showed that stents were intact at 2 weeks, but at 4, 6 and 8 weeks cracks were observed. The size of these increased gradually in accordance with the duration of exposure, and at 8 weeks several large holes in the polyurethane membrane were evident. With regard to radial tensile strength, extension and peak load at break were 84.47% and 10.030 N/mm, 54.90% and 6.769 N/mm, 16.55% and 2.452 N/mm, 11.21% and 1.373 N/mm at 0, 2, 4 and 6 weeks, respectively. Scanning electron microscopy at 2 weeks revealed intermittent pitting and cracking, and examination at 4, 6 and 8 weeks showed that the size of these defects was gradually increasing.
Conclusion: When the polyurethane membrane was exposed to bile, biodegradation was first observed at week two and increased gradually according to the duration of exposure.
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KEYWORD
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Biliary stent, Biodegradation, Polyurethane membrane,
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