Experimental microvenous reconstructions with Gore‐Tex polytetrafluoroethylene prostheses implanted by means of the sleeve anastomotic technique

Abstract

Polytetrafluoroethylene (PTFE) prostheses (Gore-Tex; ID, 1 mm; length, 5-7 mm; wall thickness, 0.2 mm; fibril length, 30 microns, n = 28) were implanted into the rat femoral vein by means of the sleeve anastomotic technique to enhance the patency rate. In the control group, PTFE prostheses (n = 8) were implanted by means of the end-to-end technique. In the experimental group patency and healing of the PTFE prostheses were evaluated at 1 day (n = 4), 1 week (n = 6), 3 weeks (n = 6), 6 weeks (n = 6), and 12 weeks (n = 6) after implantation by means of macroscopic inspection and routine light and scanning electron microscopy. All prostheses, except one at 1 week after implantation, were patent at the time of removal. All of the microvenous prostheses were completely covered by an endothelial layer at 3, 6, and 12 weeks after implantation. Occasionally some smooth muscle-like cells could be found underneath this endothelial layer, but stenosis was never observed at the anastomotic sites. Only scarce tissue ingrowth was observed in the wall of the PTFE prostheses. In the control group, all prostheses, except one prosthesis after 3 weeks, were found to be occluded. An occlusive mural thrombus was found firmly attached at the anastomoses at 1 day, and an organized thrombus at 3 weeks after implantation. The patent prosthesis demonstrated complete endothelial healing. These results demonstrate the importance of the sleeve anastomotic technique and the potential of PTFE prostheses as a microvenous conduit when implanted by means of the sleeve anastomotic technique in experimental reconstructive microvascular procedures.

Hyaluronan‐based scaffold for in vivo regeneration of the rat vena cava: Preliminary results in an animal model

“…The most important novel finding is represented by the ability of proposed vascular prostheses to sequentially orchestrate vascular regeneration events needed for small vein reconstruction. The development of reconstructive venous surgery has been hampered by the lack of suitable graft materials 1–12. There are only few evidences in the literature about the possibility to substitute a vein tract with prosthesis 1–12.…”

“…As preliminary results have been very discouraging, a minimal number of studies have been carried out and much more research is needed in this area. small‐diameter prostheses have not left the laboratory, as they have been disappointing in their high rate of thrombosis, and are still considered unreliable 1–12. Several factors are thought to play an important role in prosthetic microvenous occlusion, such as the low‐flow state combined with the thrombogenity of the graft material.…”

“…Harvesting such grafts prolongs the operation time and may compromise free tissue transfers or replantations, and so it would be advantageous to have reliable synthetic microvascular prostheses of various sizes readily available 1–3. Synthetic vascular prostheses, such as Dacron fabric grafts and Polytetrafluoroethylene (ePTFE), have been developed to supplement the limited supply of native graft materials 4–12. They perform satisfactorily in high‐flow, low‐resistance conditions in peripheral arteries larger than 5 mm, but they are not bioactive and suitable for small caliber arterial and venous reconstructions.…”

“…Thus far, both clinical and experimental replacements of microvenous segments with prosthetic conduits have been largely unsuccessful due to thrombosis. Several factors are thought to be responsible such as the thrombogenicity of the graft material and the low‐flow‐rate 4–12. At present, microvascular prostheses have proved highly unsatisfactory once inserted in the venous system, and small‐diameter prostheses have not left the laboratory, as they have been disappointing in their high rate of thrombosis, and are still considered unreliable 4–12.…”

“…Several factors are thought to be responsible such as the thrombogenicity of the graft material and the low‐flow‐rate 4–12. At present, microvascular prostheses have proved highly unsatisfactory once inserted in the venous system, and small‐diameter prostheses have not left the laboratory, as they have been disappointing in their high rate of thrombosis, and are still considered unreliable 4–12. Recent studies have focused on ECM‐based biomaterials, such as proteoglycans and glycosaminoglycans (GAGs), which could be useful as scaffolds for vascular endothelial cell (EC) regeneration, due to their presence in the vascular intima and media, and their frequent amenability to chemical stabilization with little biological alteration 13–15.…”