Coaxial Double PTFE-Silicone Graft

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Abstract
The performance of a new dialysis prosthesis designed to self-seal after puncture was tested ex vivo and in vivo. It consists of two coaxial polytetrafluoroethylene tubes (PTFE), the space between them filled with silicone rubber sealant (PTFE-sil). (1) Ex vivo: Three PTFE-sil, three double PTFE (without silicone), and three single PTFE grafts were placed sequentially between scribner shunts in the hind limb of four dogs. Bleeding on puncturing with an 18-gauge needle was measured for 30 seconds. PTFE-sil bled less than the controls (g): PTFE-sil; 16 ± 18; double PTFE: 32 ± 10; single PTFE: 52 ± 19 (p lt; 0.001). (2) In vivo: Six PTFE-sil and five single PTFE grafts were interposed between the carotid artery and jugular vein of dogs and were punctured with a 16-gauge needle on days 1, 3, and 7. Bleeding was measured through an incision over the puncture site at 5 minutes. In 11 punctures of PTFE-sil, there was no bleeding; three bled less than 20 g. In 13 control punctures, none bled less than 70 g. (3) Patency: Grafts were studied for patency in arteriovenous (AV) fistulas in 34 dogs. Each dog received a PTFE-sil graft in one groin and a single PTFE control graft in the other. At 4 months, patency rates were: PTFE-sil, 84%; single PTFE, 87% (NS). Four months after implantation, hemostasis after puncture in PTFE-sil grafts required 70 ± 49 seconds versus 207 ± 48 seconds for PTFE grafts (p lt; 0.005). In conclusion, PTFE-sil grafts are self-sealing, can be used immediately after implantation, and need minimal compression after needle removal.