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

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

[Glutaraldehyde - fixed human umbilical cord vein as a small diameter arterial substitute. Experimentation on the monkey].

Autologous saphenous veins, the preferred substitute material for aorto-coronary, femoro-popliteal and femoro-tibial by-pass, are usable in only 70% of individuals in need of such procedures. The development of small diameter substitute arteries is therefore essential to broaden the pool of patients who could benefit from this class of cardiovascular surgery. Existing substitutes, however, present major difficulties and have had limited success. In this laboratory, an attempt has been made to develop a vessel of 3 millimetres or less in diameter derived from human umbilical cord processed in glutaraldehyde. This substitute can be stored in 45% ethanol or dessicated by critical point drying. This device had been implanted as a segment of abdominal aorta in eight primates (Macaca fascicularis). Preliminary results are disappointing. The indicate that retention of a patency for more than a year post-implantation is difficultly achievable and that connective tissue hyperplasia leading to occlusion at the anastomoses is a major problem. Similar but larger diameter by-passes in the order of 6-8 millimetres should be investigated in greater detail, in order to better establish the "in-vivo" behavior of this class of tissue prosthesis. This would address the more fundamental issues pertaining to the clinical usefulness of fixed biological tissue by-pass devices.

Animals↗