Patency and Healing of Polymeric Microvenous Prostheses Implanted into the Rat Femoral Vein by Means of the Sleeve Anastomotic Technique

Abstract

The sleeve anastomotic technique was used to enhance the longer term patency and healing of polyurethane-based (PU) microvenous prostheses (ID: 1 mm, length: 5 mm, wall thickness: 0.2 mm; n = 34) in the rat femoral vein. In the control group, PU prostheses (n = 12) were implanted by means of the conventional end-to-end technique, and all were found to be occluded after one day (n = 6) and three weeks (n = 6). In the other experimental groups, the prostheses were evaluated after one day (n = 6), three weeks (n = 10), and six weeks (n = 18) of implantation by means of routine light- and scanning-electron microscopy. The occluded prostheses in the control group demonstrated a firmly attached mural thrombus at the anastomoses at one day and a completely organized thrombus at three weeks after implantation. Thirty-one of the 34 PU prostheses implanted by means of the sleeve technique were patent. At one day, all patent PU prostheses (five out of six) demonstrated minimal thrombus accumulation and a smooth transition at the anastomotic sites. At three and six weeks, all patent PU prostheses (16 out of 18) were covered by a complete endothelial layer. Underneath the endothelial layer, a subendothelial layer, composed of two to four layers of smooth muscle cells, could be observed. The wall of the prostheses were penetrated by fibrohistiocytic tissue. Stenosis was not observed. These results demonstrate that the sleeve anastomotic technique not only improves the short-term patency of PU microvenous conduits, but also the longer-term patency rate.(ABSTRACT TRUNCATED AT 250 WORDS)

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.…”

“…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.…”

Prosthetic microvenous grafting in the rat femoral vein

“…(From van der Lei et al, 1991a, with permission. ) prostheses (Robinson et al, 1989;1990;van der Lei et al, 1991a;1991b). Our earlier experience had shown the rat can provide a good experimental model (Bartels & van der Lei, 1988) and the aim of this report is to describe our experiences with prosthetic microvenous grafting techniques and microvenous prostheses in the rat femoral vein.…”