PDF(Pubmed)
Abstract：
Inflammation of the bile ducts and surrounding tissues can impede bile flow from the liver into the intestines. If this occurs, a plastic or self-expanding metal (SEM) stent is placed to restore bile drainage. United States (US) Food and Drug Administration (FDA)-approved plastic biliary stents are less expensive than SEMs but have limited patency and can occlude bile flow if placed spanning a duct juncture. Recently, we investigated the effects of variations to post-processing and autoclaving on a commercially available stereolithography (SLA) resin in an effort to produce a suitable material for use in a biliary stent, an FDA Class II medical device. We tested six variations from the manufacturer\'s recommended post-processing and found that tripling the isopropanol (IPA) wash time to 60 min and reducing the time and temperature of the UV cure to 10 min at 40 °C, followed by a 30 min gravity autoclave cycle, yielded a polymer that was flexible and non-cytotoxic. In turn, we designed and fabricated customizable, SLA 3D-printed polymeric biliary stents that permit bile flow at a duct juncture and can be deployed via catheter. Next, we generated an in silico stent 3-point bend test to predict displacements and peak stresses in the stent designs. We confirmed our simulation accuracy with experimental data from 3-point bend tests on SLA 3D-printed stents. Unfortunately, our 3-point bend test simulation indicates that, when bent to the degree needed for placement via catheter (~30°), the peak stress the stents are predicted to experience would exceed the yield stress of the polymer. Thus, the risk of permanent deformation or damage during placement via catheter to a stent printed and post-processed as we have described would be significant. Moving forward, we will test alternative resins and post-processing parameters that have increased elasticity but would still be compatible with use in a Class II medical device.
摘要：
胆管和周围组织的炎症可以阻碍胆汁从肝脏流入肠道。如果发生这种情况,放置塑料或自膨胀金属（SEM）支架以恢复胆汁引流。美国（US）食品药品监督管理局（FDA）批准的塑料胆道支架比SEM便宜，但通畅性有限，如果跨导管接合处放置，则会阻塞胆汁流。最近,我们研究了对市售立体光刻（SLA）树脂的后处理和高压灭菌变化的影响，以努力生产适用于胆道支架的合适材料。FDAII类医疗器械。我们测试了制造商推荐的后处理的六种变化，发现将异丙醇（IPA）洗涤时间增加到60分钟，并将紫外线固化的时间和温度在40°C下降低到10分钟，然后是30分钟的重力高压釜循环，产生了一种柔性和非细胞毒性的聚合物。反过来,我们设计和制造可定制，SLA3D打印的聚合物胆道支架，允许胆管接合处的胆汁流动，并且可以通过导管展开。接下来,我们生成了一个硅胶支架3点弯曲测试来预测支架设计中的位移和峰值应力。我们通过对SLA3D打印支架进行三点弯曲测试的实验数据证实了我们的模拟准确性。不幸的是,我们的三点弯曲测试模拟表明，当弯曲到通过导管放置所需的程度时(~30°),预测支架经历的峰值应力将超过聚合物的屈服应力。因此，如我们所描述的,在通过导管放置到打印和后处理的支架期间,永久变形或损坏的风险将是显著的.往前走,我们将测试替代树脂和后处理参数，这些参数增加了弹性，但仍与II类医疗器械的使用兼容。
