Covered stents in transjugular portosystemic shunt: healing response to non-porous ePTFE covered stent grafts with and without intraluminal irradiation

Abstract

The aim of this study was to evaluate the healing response to a new commercially available ePTFE-covered stent graft used to create transjugular intrahepatic portosystemic shunts (TIPS) in an animal model with and without intraluminal irradiation. The study was designed for ten domestic normotensive pigs. The TIPS was created using a ePTFE-covered stent graft (Viatorr, Gore, Flagstaff, Ariz.). Five animals were scheduled for intraluminal irradiation with iridium 192 immediately after TIPS creation with a dosage of 18 Gy. Shunt venograms were performed every 2 weeks. Animals from the irradiated and non-irradiated group were killed at 2-week intervals. Maximum follow-up was planned for 8 weeks in each group, with two animals in reserve. Gross specimen evaluation and histological examination, including scanning electron microscopy, was performed. Two animals died from interventional complications. In the irradiation group, one shunt occlusion and one stenosis occurred after 2 weeks. The stenosis regressed until the end of the 8-week follow-up period and probably was caused by a resolving thrombus. In the non-irradiated group, no shunt dysfunction was observed. One animal died early due to encephalopathy. Histology revealed an increased inflammatory reaction in the irradiation group, a lesser degree of incorporation of the stent graft, and a lesser degree of endothelialization of the inner surface compared with the non-irradiated group. No significant foreign body reaction was found at any time in any of the animals. The Viatorr stent graft was well tolerated in the pig model. Intraluminal irradiation seemed to have an adverse effect on the healing response. The TIPS patency was prolonged in both the irradiated and non-irradiated group compared with data from the literature; however, seemingly better results were observed in the non-irradiated group.

Patency and clinical outcomes of transjugular intrahepatic portosystemic shunt with polytetrafluoroethylene‐covered stents versus bare stents: A meta‐analysis

“…The high rate of shunt insufficiency (40–60% at 1 year and 70–85% at 2 years after the TIPS procedure) made close surveillance and frequent costly revisions mandatory, thus rendering TIPS creation a multistage procedure in the majority of cases when bare stents were used 2,6 . Animal experiments 25–28 and preliminary clinical studies 29–34 suggested that the use of stents covered with PTFE could improve shunt patency by avoiding the pseudointimal and intimal hyperplasia. The expandable PTFE‐covered stent‐graft designed for TIPS comprises two portions: a 2‐cm‐long noncovered segment in the portal vein allows free blood flow to side branches of the portal vein through the bare nitinol stent wires; and the expandable PTFE portion covers the inside of the stent and is placed from the portal vein entry site along the length of the parenchymal tract as far as the hepatic vein ostium.…”

Transjugular Intrahepatic Portosystemic Shunt

“…Late shunt malfunction occurs in up to 80% of cases during follow-up. Recently, the use of expanded polytetrafl uoroethylene (ePTFE)-covered stents resulted in a primary patency rate of 84% at 1 year by Kaplan-Meier analysis [41][42][43][44][45] . Broad application is currently hampered by high costs.…”

Early and long-term clinical and radiological follow-up results of expanded-polytetrafluoroethylene-covered stent-grafts for transjugular intrahepatic portosystemic shunt procedures

“…Gore and Associates, Flagstaff, AZ) has been tested on its safety and feasibility to be implanted in a TIPS both in an animal model and in humans [6,7,10]. The findings of the two published human pilot series demonstrate a high primary and secondary patency rate over 6 months to 1 year: Cejna et al described a 90% primary patency rate at 6 months, a 50% primary patency rate at 9 months and a secondary patency rate of 100% throughout the study in a mean follow-up of 289 days.…”