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Biomedical subjects

C Gosselin

Publications and source records attributed to C Gosselin.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Venous homografts as femoro-popliteal bypasses or as vascular access routes in chronic hemodialysis].

Saphenous vein homografts preserved by freezing at 40 degrees C in the presence of antibiotics for periods of as much as six months were implanted as part of a clinical evaluation program. Candidates included one requiring femoro-popliteal reconstruction with two separate bypass procedure and reoperations for thrombosis and false aneurysm in the left limb as well as 23 maintenance hemodialysis patients (32 arteriovenous blood access shunts for a total of 424 patient-months). Explanted veins used as femoro-popliteal bypasses were examined after collection incidental to reoperations and autopsy. In-vivo dwell time varied between 7 and 51 months. The femoro-popliteal by-passes exhibited calcification and sclerosis. The dialysis access shunts had average service lives of about a year; 21 were replaced because of thrombosis, 10 were stenosed, 7 had aneurysms and necrosis was present in six. Although this implant provides a workable alternative approach to vascular reconstruction, the rapid degeneration of such veins in vivo is a limitation.

Aged↗
PubMed1983

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

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.

Angiography↗
PubMed1983

Designing polyester vascular prostheses for the future.

For 30 years polyester textile materials in tubular form have been used in vascular surgery for the replacement and by-pass of arteries. Initially such medical devices were implanted to maintain the distal blood flow of atherosclerotic patients for a number of months. Today, with prognoses in excess of 10 or 15 years, and with implantation in younger and younger patients, this particular end use is possibly one of the most demanding applications for a textile product. The paper describes the current manufacturing techniques and provides detailed information about the wide variety of filaments, yarns and fabrics used in the production of current commercial devices. By reviewing the mechanical and clinical performance of available designs against the criteria of an 'ideal' prosthesis, the objective of this paper is to assist surgeons in making clinical decisions, to provide the textile and medical products industries with directions for future design improvements, and to support standards writers in their formidable task of establishing a rational standard for vascular repair devices.

Blood Vessel Prosthesis↗
PubMed1982

New alternatives in the preparation of chemically fixed human umbilical veins as arterial substitutes.

Following reports of the successful use of chemically processed human umbilical veins as medium and small diameter arterial substitutes, the development of new and improved techniques for the preparation, fixation and storage of these bioprostheses has been attempted. A series of physical and "in vitro" tests was undertaken to predict the "in vivo" performance of these devices. The results indicate that the new techniques are not only technically feasible but may provide a more convenient, versatile and effective surgical product.

Arteries↗
PubMed1982

[Analysis of silicone testicular implants after explantation].

Two juvenile size silicone testicular prostheses were analyzed following replacement by adult size devices after 72 and 99 months in situ. Scanning electron microscopy and electron microprobe studies were carried out on the explanted silicone prostheses and their attached tissue capsules. The material at the surface of the prostheses gave no evidence of biodeterioration. However, localized sites of calcification were observed. The adjacent tissue capsule consisted of two distinct concentric layers with different morphologies; the one adjacent to the prosthesis consisted of dense arrays of collagen fibres oriented parallel to the silicone surface and extending outward to a thickness of 100-120 microns. The outer layer was less dense, more disordered and was uneven in thickness. It contained numerous discrete particles of silicon-rich material. Technical and clinical implications of these results are discussed.

Adolescent↗
PubMed1982

[The use of jugular veins as carotid artery substitutes in dogs: a comparison between cryopreservation techniques and the tanning process of vein preservation (author's transl)].

Improved surgical techniques and an aging population have allowed surgeons the opportunity to implant vascular prostheses in patients where the run-off bed is somewhat compromised. We have considered the possibility of homograft venous preservation either by tanning or cryopreservation and now report our preliminary experience in the canine model jugular veins of large mongrel dogs were excised and treated in one of two manners. These veins were preserved for either seven or thirty days and inserted as functional segments in the carotid vessels: each dog received a tanned vein on one side and one which has been cryopreserved on the other side, as either an autograft or allograft. After three months the twenty one dogs were sacrified and the grafts recovered and examined for patency and histology. There appeared to be no difference in patency between the autograft and the allograft groups but there were striking differences in patency between the tanned grafts (8/21) and the cryopreserved grafts (19/21). Tanned grafts showed a fibrous hyperplasia at the anastomotic suture line that seemed to be the causative factor for graft thrombosis. Cryopreserved grafts showed sclerotic degeneration in the midportion of the graft: it was found to be more pronounced in the 30 day preservation specimens. The relatively good results, regarding patency, in the cryopreserved group has sparked our interest to investigate further into this process.

Animals↗
PubMed1981

Effects of traumatic manipulations on grafts, sutures, and host arteries during vascular surgery procedures. Experiments on dogs.

Scanning electron microscopy was used to diagnose incidents of trauma and the pattern of healing following surgical implantation of microporous blood vessel substitutes. Vascular reconstruction procedures using autogenous or synthetic prosthetic material inflict damage to the adjacent tissues as well as the prosthesis. This affects the thrombotic behavior and healing pattern of the area. The prognosis for long-term success are, as a consequence, directly influenced. Various vessel-occluding devices were evaluated in canine models with respect to their ability to damage blood vessels at the clamped site. The impact of suture needles on tissues and prosthetic materials was also considered. Of the various vessel-clamping devices which are commercially available, those which have elastomeric shields on the clamping components were found to be most satisfactory. The development of less traumatic surgical devices is discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1981

Thoraco-abdominal bypass as a method of evaluating vascular grafts in the dog.

Seven Vasculour d grafts, five Gore-Tex grafts and seven Solco-graft, 8 mm by 30 cm, implanted as thoraco-abdominal bypasses in dogs. Sixteen were retrieve at two months. Graft size was assessed angiographically in representative dogs of each group prior to sacrifice. Initial examination of the retrieved specimens revealed pannus extensions at both anastomoses on all graft types, and a variable midgraft appearance from smooth and glistening to partially thrombus coated. Histological assessment of graft segments revealed widely differing healing responses on the three graft types. Tissue attachment to both graft surfaces and varying degrees of tissue incorporation were observed in the Vasculour D and Gore-Tex prostheses. The Solco-graft specimens showed no evidence of tissue incorporation of the wall at two months. Tissue on the graft surfaces remains loosely attached and unincorporated. Pannus extensions were thickest on the Solco-graft. Variably thin fibrin is scattered over the luminal surface of the three graft types. Vascularization of the wall particularly the internal capsulae was noted in the Vasculour D grafts. Although biological responses in the dog are difficult to extrapolate to man, the types of comparison testing allowed by the use of the thoraco-abdominal by-pass procedure can provide valuable information of degree of dilation, relative tissue attachment, tissue incorporation into various types of prostheses and kidney infarcts study. The greatest value of the thoraco-abdominal by-pass lies in graft sizes and length without special regard for patency: assessment of graft size post-implantation and structural changes is then made possible.

Abdomen↗
PubMed1981

[Aneurysm formation on dacron prosthesis after 84 months of use. Pathology, structural and chemical evaluation of the explanted device (author's transl)].

A 56 year old patient fitted with a femoro-popliteal Dacron prosthesis (Weavenit-Meadox Medical) 84 months earlier, presented with a severe palpable dilation in the middle part of the graft. The dilated segment of the prosthesis was resected locally and spliced to a new fabric device. The explanted section of prosthesis was analyzed; the dilation was found to extend only over several centimeters near the centre of the prosthesis. The degree of "healing" was found to be satisfactory except in the part which was most distended; this area also revealed mild bacterial colonization. Physico-chemical analysis of the fabric revealed that the dilation had taken place subsequently to hydrolytic degradation of the polyester fibres. Manufacturing conditions may have contributed to predisposing parts of the prosthesis to accelerated biodeterioration in vivo.

Biodegradation, Environmental↗
PubMed1981

[Liquid storage media for vascular prosthesis of biological origins : their impact on biocompatibility (author's transl)].

Unlike synthetic arterial substitutes which are supplied as presterilized, dry-packaged products with potentially indefinite shelf lives, arterial prosthesis of modified biological origin must stored in less convenient liquid preservative media. These preservatives can affect the post-implantation performance and the biocompatibility of the devices. In order to identify the most suitable media, a modified "in vitro" cell culture test method was developed. It makes use of endothelial cells prepared from the aorta of chick embryo. In general, the prosthesis stored in liquid media had a disappointing performance from the point of view of neo-endothelium development and adhesion. Residual cytotoxicity was also noted for most of these currently used prosthesis storage and pre-surgical preparation protocols. Although devices stored in physiologic media showed adequate biocompatibility according to this cell culture test, it appears that neo endothelialization does not proceed concurrently with healing. Cellular development where present, adheres poorly to the substrate and cannot resist the shear forces of normal blood flow. Pre-implantation treatment of such prosthesis with cellular growth-promoting substances may enhance cell-prosthesis adhesion.

Animals↗
PubMed1980

Another look at the Sparks-Mandril arterial graft precursor for vascular repair. - Pathology by scanning electron microscopy.

The Sparks-Mandril blood vessel precursor system, an autogenous tissue growth-promoting device, in spite of its ingenuity and its surgical elegance, has received only limited usage. At technique for peripheral blood vessels by several authors. In the latter period, this laboratory also undertook similar work. The results of seven implantations in dogs and two in patients are reported here in the context of a program on the evaluation of blood vessel substitutes, their mode of operation and their long term performance. The clinical status and the pathology of the grafts at time of failure were investigated using techniques of scanning electron microscopy. This work confirms the findings of other centres regarding the generally unsatisfactory performance of the Sparks-Mandril system. Possible causes for failure in mandril-formed blood vessels are discussed.

Adult↗
PubMed1980

[Polyethylene terephtalate (Dacron) prostheses as arterial substitutes. Value of commercial grafts as abdominal aorta substitutes in the dog (author's transl)].

Most of the presently available Dacron fabric grafts are either woven or knitted; some are velours. Whereas the various configurations and textures can be easily recognized and classified with respect to morphology, structure, porosity and fabric tenacity, it is also necessary to establish their post-implantation healing characteristics. Canine models have been used to investigate the healing characteristics of 18 types of prostheses over implantation periods from one to six months using techniques of scanning electron microscopy and conventional light microscopy. Velours exhibit superiar tissue ingrowth but the internal tissue lining does seldom embeds all of the fibres. Complete neoendothelialization is not achieved; the process appears more closely linked to haemodynamic factors such as shear forces acting postfacto on blood deposits as opposed to graft porosity facilitating ingrowth. More meaningful criteria of performance must be found to allow a closer matching between the available products and the individual clinical needs of each situation.

Animals↗
PubMed1980

Cardiovascular sutures as assessed by scanning electron microscopy.

Nine types of commercial sutures were investigated with respect to their suitability in cardiovascular surgery involving anastomosis of arterial prostheses. Polyester, nylon, silk and polypropylene in the form of multifilaments and monofilaments with or without coatings were included. The gross structure of the suture and the needle, the uniformity of the fibres and the coatings, the mechanical properties, before and after surgical use and the quality of the resulting anastomoses in canine models were evaluated. Although all surveyed products were potentially usable for the purpose intended, some appeared more suitable. Intraoperative damage to the sutures was found to be extensive and may play an important part in the long-term security of the anastomoses.

Cardiac Surgical Procedures↗
PubMed1980

A SEM investigation of the trauma to prostheses and arteries during vascular reconstruction procedures.

Scanning electron microscopy was used to diagnose incidents of trauma and the pattern of healing following surgical implantation of microporous blood vessel substitutes. Vascular reconstruction procedures using autogenous or synthetic prosthetic materials inflict damage to the adjacent tissues as well as the prosthesis. This effects the thrombotic behavior and healing pattern of the area. The prognoses for long term success are, as a consequence, directly influenced. Various vessel occluding devices were evaluated on canine models with respect to their ability to damage blood vessels at the clamped site. The impact of suture needles on tissues and prosthetic materials was also considered. Of the various vessel clamping devices which are commercially available, those which have elastomeric shields on the clamping components were found to be the most satisfactory. The development of less traumatic surgical devices and possible modifications in the surgical protocols are discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1980

[Evaluation of two commercial bovine vascular heterografts (author's transl)].

Two commercially available grafts made from chemically modified bovine carotif arteries, Artegraft (Surgikos Corp. U.S.A.) and Solcograft (Solco A.G. Switzerland), were evaluated. Preliminary evaluation indicates that these products compare favorably with other more common chemically treated grafts of biological origin. Morphological characteristics, inflammatory response and thrombogenic potential were measured. Their structure suggest that each of the processes conserve the collagen morphology of the media and the adventitia originally present in the precursor arteries. Test implantations in dogs reveal a tendency to undergo stenosis near the anastomoses within a few months. After six months of in-vivo function, these grafts are not invaded with the expected neo-formed cells and new collagen in their central portion; this process takes place only near the anastomoses.

Animals↗