Polyester prostheses as substitutes in the thoracic aorta of dogs. I. Evaluation of commercial prostheses

Abstract

Using canine models, a representative selection of polyester or Dacron vascular prostheses, including woven, knitted, and velour types, were evaluated for their relative healing characteristics and for their structural changes during implantation. Following residence periods ranging from 4 h to 6 months at the site of the thoracic aorta, the dogs were sacraficed, and the grafts were excized for measurement of the thrombogenicity of the flow surface and for pathological examination by light microscopy and SEM. The kidneys were also removed and examined for infarcts caused by any trapped circulating emboli. The extent of healing, the presence of embolizing nuclei, and the thrombogenicity and morphology of the lumen surface were also assessed. The healing characteristics of each type of device proved similar. Velour fabrics exhibited more extensive encapsulation, but frequently their internal capsules failed to incorporate all the fibers. In all cases, cellular development on the lumen was limited to areas contiguous to the anastomoses. The initial porosity of the devices as measured by water permeability did not appear to influence the healing sequence to a significant extent. The grafts did exhibit differences in structural stability depending on whether they were of a knitted or woven construction. We suggest that users consider these different mechanical and structural properties when making their choice of a graft. Despite these differences, we believe that the healing process is far more host dependent than graft dependent.

Polyester Arterial Grafts Impregnated with Cross-Linked Albumin: The Rate of Degradation of the Coating in vivo

“…Both scries involved implanting an 8-to 10-cm-long segment of the prosthesis impregnated with marked albumin in the thoracic aorta according to a standardized labora-tory protocol [5]. In addition, a 5-cm-long segment of the same prosthesis was inserted in the peritoneal cavity o f the same animal and sutured to the abdom inal wall.…”

“…Ideally, the albu min should prevent acute thrombotic accu mulations within the first few hours follow ing implantation and should prevent blood oozing through the graft wall during the pe riod of fibrinolytic response by the host, i.e., 24-72 h after implantation [11]. However, it should begin to degrade after a week in vivo and, through progressive exposure of the po lyester substrate, should promote the gradual accumulation of a thrombotic matrix on the luminal and external surfaces which in turn leads to encapsulation of the graft by a ho mogeneous tissue layer [5], Should the albu min coating degrade in vivo at either too fast or too slow a rate, then this desirable healing sequence will not be achieved. The objective of this study therefore was to determine the relative rates of biodegradation of albumin cross-linked with either glutaraldehyde or carbodiimide by implanting coated grafts in the thoracic aorta and in the peritoneal cav ity of dogs for prescheduled periods of up to 4 weeks.…”

In vivo Evaluation of Polyester Arterial Grafts Coated with Albumin: The Role and Importance of Cross-Linking Agents

“…The implantation procedure for inserting the 8-mm-diameter, 8-cm-long sections into the canine tho racic aortas followed the standardized laboratory pro tocol that has been described elsewhere [14]. The albuminated grafts were rehydrated in saline prior to implantation for one of eight preselected periods, namely 4 h, 24 h, 48 h, I week, 2 weeks, 1 month, 3 months and 6 months.…”

“…A standardized protocol, reported previously [ 14], was followed for the sacrifice of the animals and for the collection of the explanted grafts and the kidneys. The following sequence of tests and examinations were made on each specimen [19], (a) The pathology was studied by light and scan ning electron microscopy [12], The explanted grafts were fixed in GTA, rinsed in distilled water postfixed in osmium tetraxide (1%), rinsed again and dehy drated in a series of aqueous ethanol solutions (70 and 90%) and pure ethanol (100%).…”

“…The quality of the staining was judged by its specificity and the lack of background stain. The control samples were also systematically stained for comparison [6], (c) The pathology of the kidneys was evaluated by light microscopy [14].…”