A Novel Microporous Polyurethane Vascular Graft: In Vivo Evaluation of the UTA Prosthesis Implanted as Infra-Renal Aortic Substitute in Dogs

Abstract

A novel microporous polyurethane blood conduit developed at the University of Texas at Arlington was implanted as an infra-renal substitute in dogs. The prosthesis was fabricated by precipitating a solution of the polymer with dry nitrogen onto a rotating mandrel. The grafts were sterilized either by gamma radiation (series I) or ethylene oxide (series II); they were implanted for the following prescheduled periods: 4, 24, 48 hours, and 1 week (short-term) and 2, 4 weeks, 3 and 6 months (medium-term). The thrombohematological characteristics of each animal were evaluated prior to implantation and confirmed that the index of blood coagulability was normal. In the short-term group, five out of eight grafts were patent and three were partially occluded; four grafts in the medium-term group were patent; one was partially occluded; and three were thrombosed at retrieval. One week after implantation, the prostheses were surrounded by an external capsule, which was present mainly at the two anastomoses. The external capsule covered the entire graft at 3 months. No kinking of the grafts was observed and the presence of a mild yellow stain related to bilirubin uptake was detected at 2 weeks, 1, 3, and 6 months. Histological studies have revealed the formation of a thin internal capsule at both anastomoses, 2 weeks postimplantation, which was not anchored to the graft wall. In the medium-term group, the thrombosed grafts failed to develop an internal capsule, whereas the patent graft exhibited a thick internal capsule made of neocollagenous tissue over the entire graft. This new microporous polyurethane prosthesis did not perform satisfactorily as an infra-renal substitute in dogs and its in vivo stability requires further assessment. Thus, the concept of a polyurethane with closed pores does not achieve what was anticipated.

Selection of a Polyurethane Membrane for the Manufacture of Ventricles for a Totally Implantable Artificial Heart: Blood Compatibility and Biocompatibility Studies

“…On the other hand, this study showed that both PEU membranes demonstrated good hemocompatibility and low levels of complement activation. However, these results must be interpreted with caution as Tecoflex‐based and PEU Mitrathane (Biomer‐like) arterial grafts were shown to be highly thrombogenic (19,20). The authors of these studies recognized, as have others, that the type of graft wall structure and topography also contribute to the thrombogenic behavior of these prostheses.…”

Influence of weft‐knitted tubular fabric on radial mechanical property of coaxial three‐layer small‐diameter vascular graft

“…Because of its excellent elasticity and biocompatibility,15–22 polyurethane has been widely regarded as the best candidate to solve the compliance problem. Many polyurethane vascular grafts have been fabricated using different methods 23.…”

Small diameter Polyurethane vascular graft reinforced by elastic weft-knitted tubular fabric of polyester/spandex

“…However, graft thrombosis is still a serious clinical problem in spite of continuous improvements in graft development [14]. Polyurethane has been used to solve the thrombus problem due to its excellent elasticity and biocompatibility, and a microporous structure can be successfully fabricated in the wall using different methods [15][16][17][18][19][20][21][22]. The porosity of commercially available polyester (Dacron) knitted vascular grafts can be reduced by coating or sealing with a novel ionic urethane, to improve their blood-proof property.…”