Short-term Patency and Safety of an Expanded Polytetrafluoroethylene Encapsulated Endoluminal Device at the Venous Anastomosis of a Canine Arteriovenous Graft Model

Abstract

To determine the safety and short-term patency of a polytetrafluoroethylene (PTFE)-encapsulated carbon-lined endoluminal device (ED) deployed across the venous anastomosis of arteriovenous conduits. Arteriovenous grafts (n = 16) were created between femoral arteries and veins in eight female canines and allowed to mature 30 days +/- 5 (SD). Five were excluded before implantation because of thrombosis or intragraft stenosis. Deployment was conducted in the remaining 11 anastomoses. Fistulography and intravascular ultrasound (IVUS) were performed before and after the procedure and 1 month postimplantation. Stent migration, apposition, and stenosis were evaluated. The angle of the anastomosis was compared before and after deployment and at follow-up. Mural thrombus thickness, percentage of surface covering, and percentage of endothelialization within the device were measured histologically. There was no significant migration. By explant, all devices were completely apposed. Stenosis occurred in three of nine grafts. The angle of the venous anastomosis decreased by 29.5 degrees (posteroanterior) and 32.4 degrees (oblique) after ED deployment. There was a further decrease of 6.1 degrees (posteroanterior) and 3.2 degrees (oblique) during the 4-week follow-up period. Hemostasis was difficult to achieve in this animal model. Five required more than 1 hour to achieve hemostasis manually. Six in three animals were closed with a Perclose device, achieving immediate hemostasis; however, three (one in each animal) re-bled intermittently 2 weeks after implantation for an average of 9.3 days. The puncture site of each graft that bled was radiographically shown abnormal. The ED can be deployed without stent migration and is completely apposed and patent after 4 weeks. Although bleeding was a problem with this animal model, delayed bleeding complications associated with puncture site abnormalities were seen only in grafts closed with a percutaneous suturing device.