Small intestinal submucosa sandwich Zilver stent-grafts for TIPS: experimental pilot study in swine.

The aim of this study was the evaluation of preliminary suitability of the piglet small intestinal submucosa ( SIS) sandwich Zilver endograft for experimental transjugular intrahepatic portosystemic shunt ( TIPS) creation. TIPS was created in six swine. The five surviving animals underwent the follow- up portogram and were sacrificed at four weeks after TIPS creation. Gross and histologic examination was performed in all animals. TIPS creation was successful in all animals. One animal died four days after TIPS creation. In the five surviving animals, one shunt was occluded and four shunts were stenosed on the follow- up portogram. The mean percentage narrowing of the most advanced stenoses was 72% ( range, 60% - 100%). The most advanced stenosis was located in the parenchymal tract in three shunts and in the hepatic vein portion in one shunt. Gross and histologic examination showed abundant neointimal formation composed mainly of fibroblasts leading to the significant shunt stenoses. The piglet SIS sandwich Zilver stent- graft was found to offer only limited TIPS patency and should not be used for the definitive long-term TIPS study.