Polyester Vascular Prostheses Research Articles

An arterial prosthesis from Argentina: the Barone Microvelour arterial graft.

The manufacture of a polyester vascular prosthesis in the southern hemisphere is a new development in the global dissemination of this maturing technology. Hence the recent introduction of the Barone Microvelour arterial graft from Argentina has highlighted the need for a comparative in vitro and in vivo study to compare its structure and performance with that of existing commercial products. Following a series of laboratory tests and implantations as a thoracoabdominal bypass in dogs, the Barone Microvelour has been identified as a strong graft constructed after the style of early weft-knitted designs. It provides an equivalent sequence and rate of healing to that of other polyester knitted grafts.

Radiosterilization of albuminated polyester prostheses

The study reported here is concerned with the radiosterilization of Dacron ® vascular prostheses coated with crosslinked albumin. γ-Radiations have no effect on the mechanical properties of the polyester fibres or on their crystallinity, whether irradiated in a dry state or immersed in saline. Special attention has been paid to the release of the albumin, or protein fragments from the reticulum using 125I-labelled albumin as a radiotracer. The albumin leakage depends upon the type of Dacron ® fabrics considered but the values derived from radioactivity measurements are always greater than those directly measured, which indicates a radioinduced break of the bond between iodine and albumin; this has nothing to do with the break of the association between albumin and Dacron ®. Moreover no cytotoxicity of the irradiated immersion medium has been observed using a test based on organotypic culture in liquid medium. Thus radiosterilization of an albuminated polyester vascular prosthesis immersed in saline appears to be a suitable procedure.

Albumin-coated polyester arterial prostheses: is xenogenic albumin safe?

This paper adds a new dimension to the series of studies concerned with the development of an albumin-coated polyester vascular prosthesis by addressing the question of the origin of the albumin. Previous experiments in dogs have used canine albumin-coated polyester arterial grafts. This study evaluated the biocompatibility of xenogenic material by implanting in dogs prostheses coated with bovine albumin and cross-linked with glutaraldehyde. Two series of albuminated grafts, one gamma radiation sterilized, the other ethylene oxide sterilized, as well as a preclotted control series were undertaken. The origin of the albumin did not appear to be significant. In fact, the healing pattern of the xenogenic albumin coated grafts was identical to that found previously with isogenic albumin. Nor did the method of sterilization produce significantly different pathological results. However, a slower rate of healing with the coated grafts compared to the preclotted controls did appear to be related to the slow rate of albumin erosion and the potentially cytotoxic effect of the glutaraldehyde cross-linking agent.

The cytocompatibility of compound polyester-protein surfaces using an in vitro technique.

To avoid the need to preclot porous polyester (Dacron) vascular prostheses, we have proposed the use of a protein coating that will promote the growth and adhesion of endothelial cells. This study assessed the relative advantages of coating woven, knitted, and velour polyester fabrics with albumin, collagen, and a albumin-collagen mixture after preservation in saline or drying by a commercial dehydration process. Preclotted fabrics were used as controls. The cytocompatibility of these biopolymers was measured by an organotypic culture technique which relies on the migration of chick embryonic endothelial cells. After 7 d of culture the cytocompatibility was quantified by counting the cells in the area of migration and the morphology of the endothelial cells was observed by scanning electron microscopy. In general, the knitted and velour fabrics showed superior compatibility than the woven one. The results confirmed that collagen, either alone or combined with albumin, provides in most cases a more cytocompatible surface than albumin alone. A cell morphology most closely resembling that of natural arterial endothelial cells was observed on the albumin-collagen substrate.

Radiation crosslinked hydrogels as sustained release drug delivery systems

Radiation methods have been used for: i/ modification of vascular prostheses, ii/ obtaining burn dressing materials enabling controlled drug release, iii/ the preparation of polymer ocular insert discs. The surface of polyester vascular prostheses, has been modified by deposition of acrylamide and inducing its polymerization in the solid state by j  -radiation. As a result of this treatment, tightness of the prosthesis walls and its surface hydrophilicity have been improved. Toxicological examinations and blood hemolysis studies of modified prostheses showed its good biocompatibility. Various burn dressings have been prepared and the most promising of all investigated turned to be composition consisting of a cotton gauze base and an active polyacrylamide hydrogel layer with addition of glycerin and immobilized Provital /protein preparation/. Preliminary clinical evaluations of this particular dressing showed that the process of burn healing is indeed fast and fully satisfactory. Ocular insert discs made of polymer and containing pilocarpin hydrochloride which is released at controlled rate have been prepared. It has been found that high hydrophilicity and good swelling properties of the ocular insert discs made possible to incorporate pilocarpin hydrochloride into the hydrogel matrix. This work has been carried out under IAEA research contract RB 3379/R-1 POL.

Pathological changes of anastomotic false aneurysms.

Anastomotic parts of polyester vascular prostheses implanted in thoracic aortae of 270 dogs were examined. Anastomotic false aneurysms were seen with 3 cases (1.2%), in which disruption did not occur, however, the grafts which have no aneurysm showed the following features, i.e., suture migration, degenerative changes of the host arterial wall sustaining a suture and dissection between the host arterial wall and a prosthesis. From the results of an analysis of the arrangement pattern of smooth muscle cells in neointima, it was clarified that a suture had been subjected to continuous tensile stress. So that, the host arterial wall sustaining a suture is clinched and pulled toward prosthesis by the suture at every pulsation during implantation. These results indicate that the features mentioned above are phenomena of the developing into anastomotic false aneurysms.

Analytic research of biomedical responce to polyester vascular prosthesis

Analytic research of biomedical responce to polyester vascular prosthesis