In an attempt to find an alternative procedure to the preclotting of porous textile vascular prostheses, the feasibility of an albumin coating and ethanol preservation technique has been evaluated by implanting albuminated polyester prostheses as substitutes in the thoracic aorta of dogs. Nine different grafts representing woven, knitted, and velour constructions were implanted for periods ranging from 4 h to 6 months. At the sacrifice, the grafts were excized for measurement of the thrombogenicity of the flow surface, for pathological examination by light microscopy and SEM, and for quantifying the changes in the textile structure during implantation. Also the kidneys were removed and examined for infarcts caused by trapped circulating emboli. The healing characteristics of the nine different grafts proved similar and followed the same sequence of events as preclotted control grafts. The albumin coating and ethanol preservation resulted in a somewhat slower rate of healing. Yet, given sufficient time, a more completely healed graft was achieved as evidenced by the presence of endothelial-like cells throughout the length of the graft. In addition, the albumin is believed to reinforce the textile structure by reducing the tendency to stretch and dilate in vivo.

Albumins↗

PubMedDate not supplied

Histopathologic findings in synthetic and biologic explanted grafts used in peripheral arterial reconstruction.

Surgically explanted vascular grafts, including 47 autografts, 14 allografts, 103 chemically processed human umbilical vein (HUV) grafts, and 406 polytetrafluoroethylene (PTFE) grafts, were studied histopathologically. Autografts, HUV, and PTFE grafts were implanted mostly in the femoropopliteal position, whereas allografts were used as a blood access for hemodialysis. The main cause for explantation in autografts (53.6%), HUV (74.8%), and PTFE (61.3%) was thrombosis, whereas allograft failure was usually related to aneurysmal degeneration (72.7%). The infection rates of HUV (20.9%) and PTFE (25%) grafts were higher than those of autografts (4.8%) and allografts (9.1%). Furthermore, bacterial colonization occurred more frequently in HUV (63.9%) and PTFE (64.7%) than in autografts (6.7%) and allografts (0%). Leukocyte infiltration was detected mostly in HUV (39.4%) and PTFE (27%) explants. Autografts and allografts both showed a 7.1% rate of lipid uptake, whereas lipid retention was observed in 84.9% of HUV and 79.8% of PTFE grafts. These results suggest that biologic vascular grafts are to be used preferentially in small diameter arterial reconstruction because of their resistance to bacterial colonization and lipid uptake.

Adult↗

PubMedDate not supplied

Can collagen impregnated polyester arterial prostheses be recommended as small diameter blood conduits?

A collagen impregnated graft and its parent preclotted prosthesis were implanted as thoraco-abdominal bypasses in dogs for periods ranging from 4 hr to 6 months and evaluated for their ease of handling, imperviousness, and healing behavior in terms of luminal surface thrombogenicity using labeled platelets and fibrinogen, prostacyclin (PGI2) secretion, histomorphometric determination of internal capsule thickness, and histopathologic and scanning electron microscopic studies. The collagen impregnated graft was impervious to blood and both grafts showed excellent handling characteristics. Fibrin uptake was negligible on both grafts; however, platelet uptake was higher on the collagen impregnated graft than on the control graft at 4 and 24 hr. The healing behavior of the collagen impregnated graft was also found to be different than that of the control graft between 1 and 6 months post implantation. The development of a host collagenous internal capsule at the anastomoses, and a confluent endothelial lining, was observed in both grafts at 1 month; in later implantation periods, the healing of the medial region was found to be more irregular in the collagen impregnated grafts, showing a lower mean PGI2 secretion than the preclotted control grafts. Histomorphometric analysis showed the internal capsule on the collagen impregnated grafts to be thicker than on the control grafts for most periods of implantation. The current study illustrates that the healing process of collagen impregnated grafts is delayed and that bovine collagen has a stimulating effect on tissue encapsulation. Current impregnated polyester arterial prostheses therefore cannot be recommended as small diameter blood conduits.

Animals↗

PubMedDate not supplied

[Demonstration of the specificity of relaxin].

Explore the source record for details and available documents.

Relaxin↗

PubMedDate not supplied

Chemically processed bovine heterografts of the second generation as arterial substitutes: a comparative evaluation of three commercial prostheses.

The use of chemically processed bovine heterografts is primarily confined to the construction of arterio-venous blood accesses in those patients requiring hemodialysis, plasmapheresis or chemotherapy. The grafts of the first generation i.e. Artegraft and Solcograft are now being supplanted by those of the second generation i.e. Reinforced Artegraft, Solco P and NCGT. We have investigated these three types of arterial prostheses as a biomaterial in terms of sterility, inflammatory response and cytocompatibility and as a blood conduit in dogs in terms of patency and healing. For each type of graft, two implantations were carried out for durations of 4 hours, 24 hours, 48 hours, one week, two weeks, one month, three months, and six months. Therefore a total of 48 grafts were implanted. All grafts but five were patent at sacrifice: thromboses were observed in two Reinforced Artegraft (after two weeks and after one month) and in three NCGT (after 24 hours, after 48 hours, and after one month). Therefore the following patencies were observed: Reinforced Artegraft 14/16, Solco P 16/16 and NCGT 13/16. In all the patent grafts, the healing was reduced to the formation of a pannus along both anastomoses; thrombotic accumulations were observed on the surface defects of the grafts, particularly the NCGT graft. The Reinforced Artegraft presents only minor advantages over the previous Artegraft; the Solco P, somewhat more acceptable is no longer commercially available since the manufacturer withdrew it after early clinical failures. The improvements noted in the bovine heterografts of the second generation appear to be marginal as compared to those of the first generation.

Anastomosis, Surgical↗

PubMedDate not supplied