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At least 19 recordsLinked to original sources

PubMed1992

Modified polytetrafluoroethylene: indium 111-labeled platelet deposition on carbon-lined and high-porosity polytetrafluoroethylene grafts.

Platelet accumulation on carbon-lined (CL) and high-porosity (HP) polytetrafluoroethylene (PTFE) grafts was investigated in vivo. In experiment 1, 20 CL grafts and 20 control PTFE grafts, each 5 cm in length and 4 mm in diameter, were interposed into both carotid and femoral arteries of 10 dogs. In experiment 2, 12 HP grafts (90 microns mean internodal distance) and 12 control PTFE grafts were implanted in six dogs. Indium 111-labeled platelets were injected intravenously and the grafts were retrieved 48 hours later. Radioactivity of the grafts and a control segment of the carotid artery was counted. A graft platelet accumulation index (GPAI) was calculated as the ratio of emission from the graft compared to that from the control segment. The GPAI of the CL graft was significantly less than the GPAI of the control graft in both the carotid (control 29.7 +/- 5.46, CL 22.3 +/- 6.55; n = 9 [p < 0.05]) and the femoral arteries (control 30.7 +/- 9.65, CL 22.0 +/- 6.59; n = 9 [p < 0.05]). There was no significant difference in GPAI between the control and HP grafts in the carotid arteries (control 30.6 +/- 11.8, HP 31.5 +/- 9.71; n = 6) and in the femoral arteries (control 31.5 +/- 7.88, HP 34.0 +/- 4.97; n = 6). Carbon lining decreases platelet accumulation on PTFE grafts in the early postoperative period, and HP grafts do not exhibit increased platelet uptake.

Animals↗

PubMed1979

Extra-anatomic bypass with expanded polytetrafluoroethylene.

Expanded polytetrafluoroethylene has been used successfully for femoropopliteal bypass, aortopulmonary bypass and as a venous substitute. Thirteen patients with impending limb loss had extra-anatomic bypasses with expanded polytetrafluoroethylene. Five patients with unilateral iliac disease had femorofemoral bypass for impending limb loss, and five debilitated patients underwent axillofemoral and bifemoral bypass for limb salvage. Nine of ten patients had salvage of the extremities. Three patients had extended profundoplasty, two combined with polytetrafluoroethylene femoropopliteal bypass to isolated popliteal artery segments. Two of these patients had limb salvage. The patency rate is 92 per cent, and the limb salvage rate is 85 per cent in this difficult group of patients. The follow-up period extends to 28 months, and 12 patients are beyond one year. In six patients, polytetrafluoroethylene carotid subclavian bypass was performed for the subclavian steal syndrome; all patients had relief of the symptoms. One patient underwent axillary-axillary bypass with excellent results. Expanded microporous polytetrafluoroethylene with its high patency, shortened operating time, biocompatibility and excellent tissue incorporation is an excellent arterial substitute. The pliability and no requirement for preclotting make polytetrafluoroethylene ideally suited for patch angioplasty and suturing in areas difficult to expose.

Adult↗

PubMed1992

Comparison of the peritoneal cells elicited by oxidized regenerated cellulose (Interceed) and expanded polytetrafluoroethylene (Gore-Tex Surgical Membrane) in a murine model.

OBJECTIVE: The peritoneal fluid cell responses to the available barriers used to prevent postoperative adhesions, oxidized regenerated cellulose (interceed) and expanded polytetrafluoroethylene (Gore-Tex Surgical Membrane), were compared. STUDY DESIGN: Oxidized regenerated cellulose and expanded polytetrafluoroethylene were inserted into the peritoneal cavity of mice and the peritoneal fluid cell number, differential cell count, morphologic type, adherence to plastic, and phorbol-12,13-myristate acetate-stimulated hydrogen peroxide production evaluated. Peritoneal fluid cell attachment to oxidized regenerated cellulose and expanded polytetrafluoroethylene was evaluated by electron microscopy. RESULTS: Oxidized regenerated cellulose promptly elicited increased numbers of large, morphologically activated peritoneal fluid macrophages that adhered more rapidly and produced more hydrogen peroxide than controls. Expanded polytetrafluoroethylene gradually increased the number of normal-appearing peritoneal fluid macrophages with increased hydrogen peroxide production but normal adherence. Macrophages rapidly attached to both materials in vivo, with oxidized regenerated cellulose being rapidly degraded. CONCLUSION: Oxidized regenerated cellulose, to a greater extent than expanded polytetrafluoroethylene, elicits an acute peritoneal fluid inflammatory exudate in the mouse, which may contribute to the oxidized regenerated cellulose-induced peritoneal injury and de novo adhesions observed in this model.

Animals↗

PubMed1992

Polytetrafluoroethylene interposition grafts for carotid reconstruction.

Polytetrafluoroethylene interposition grafts were used for carotid reconstruction in 26 operations performed in 23 patients during a 7-year period. There were 10 men and 13 women with a mean age of 66 years. The indication for interposition graft placement was recurrent stenosis with inability to perform endarterectomy in nine operations, a severe kink or technical problem during endarterectomy in nine, aneurysmal changes of the artery in six, and thrombosis of the endarterectomy site segment with stroke in two. There were no perioperative deaths and no further perioperative neurologic complications. Follow-up with performance of yearly duplex scans was obtained in all patients, and the mean duration of follow-up was 36 months. One patient (4%) died of end-stage pulmonary disease during the study interval. Occlusion of the polytetrafluoroethylene graft occurred at 12 months in one patient (4%). Hemodynamically significant restenosis developed in two patients (8%), and two patients (8%) had mild restenosis. Evidence of a second restenosis developed in three of the nine patients who underwent polytetrafluoroethylene interposition graft placement for carotid restenosis. On the basis of our study results, we conclude that polytetrafluoroethylene can be used effectively for carotid reconstruction when an interposition graft is required. However, recurrent stenosis occurs. Patients who undergo polytetrafluoroethylene interposition graft placement for carotid restenosis appear to be at high risk for a second restenosis.

Aged↗

PubMed1992

Implantation of in vitro endothelialized polytetrafluoroethylene grafts in human beings. A preliminary report.

To assess the impact of in vitro endothelialization on prosthetic graft patency, we performed femorotibial reconstruction in four patients. Polytetrafluoroethylene grafts (6 mm), lined with cultivated autologous endothelial cells, harvested from the veins of the forearm, were used. Autologous endothelial cells were harvested enzymatically and characterized by morphology and factor VII staining. After a cultivation period of 17 to 23 days, the cell count increased from 27 +/- 3 x 10(4) endothelial cells to 5.4 +/- 1.1 x 10(6). Endothelial cell seeding on polytetrafluoroethylene prostheses was then performed. To improve endothelial cell attachment to the graft surface, polytetrafluoroethylene grafts (60 to 70 cm; 6 mm diameter) were precoated with fibrin glue containing fibrin and fibronectin and the fibrinolysis inhibitor aprotinin. Seeding density of 49 +/- 10 x 10(3) endothelial cells per square centimeter yielded a preconfluent monolayer immediately after seeding, as demonstrated by scanning electron microscopy. A second cultivation period of 6 days, after seeding and before implantation, was necessary for establishment of a confluent monolayer and to allow for maturation of the endothelial cell cytoskeleton as well as production and excretion of extracellular matrix. Grafts endothelialized in vitro were implanted in four patients requiring femorotibial reconstruction. Scintigraphic studies with indium 111-labeled platelets demonstrated little or no platelet deposition, indicating persistent endothelialization. All grafts remained patent at 3 months after implantation.

Aged↗

PubMed1992

Epiglottic augmentation by use of polytetrafluoroethylene to correct dorsal displacement of the soft palate in a standardbred horse.

A 2-year-old 400-kg Standardbred colt with a history of exercise intolerance was determined to have dorsal displacement of the soft palate (DDSP). Standing endoscopy revealed a soft, flaccid, and hypoplastic epiglottis and arytenoid cartilages that moved symmetrically and abducted fully. Lateral laryngeal radiography was used to calculate a corrected thyroepiglottic length of 6.48 cm. Videoendoscopy during exercise on a high-speed treadmill at standardized treadmill speeds was performed weekly for 3 consecutive weeks. The soft palate dorsally displaced at each examination. A sternohyoideus/sternothyroideus myectomy was followed by 2 weeks of stall rest and 2 weeks of treadmill training. Because endoscopy during exercise at standardized treadmill speeds caused the horse to dorsally displace the soft palate once a week for 3 weeks after the myectomy, this surgery was deemed ineffective in this horse. Epiglottic augmentation was performed by injecting 7 ml of polytetrafluoroethylene into the ventral submucosal space of the epiglottis. After 21 days of stall rest and 5 weeks of pasture rest, the horse was placed on a 2-month treadmill conditioning program. Using endoscopy at standardized treadmill speeds, exercise efforts to encourage DDSP were unsuccessful, which suggested that epiglottic augmentation by use of polytetrafluoroethylene was an effective surgical treatment to correct dorsal displacement of the soft palate in this horse. It is believed that polytetrafluoroethylene increases the rigidity of the epiglottis, allowing it to maintain the ventral position of the soft palate.

Animals↗

PubMed1992

Injectable bioglass as a potential substitute for injectable polytetrafluoroethylene.

Injectable polytetrafluoroethylene (Teflon) and collagen have inherent problems that may prevent their long-term success. In search of a different injectable biomaterial we confirmed in rabbits the safety of injected Bioglass particles suspended in sodium hyaluronate. A second study was performed testing the ability of the Bioglass suspension to increase urethral resistance in pigs. Bioglass particles in suspension have the potential to substitute for polytetrafluoroethylene or collagen in the treatment of urinary incontinence or vesicoureteral reflux.

Animals↗

PubMed1992

Delayed postoperative bleeding from polytetrafluoroethylene carotid artery patches.

Patch angioplasty of the internal carotid artery after endarterectomy has been advocated as a means of decreasing early postoperative carotid artery thrombosis, as well as reducing the incidence of recurrent carotid artery stenosis. Noninfectious rupture of saphenous vein patches in the early postoperative period has been reported by several authors, leading others to advocate the use of prosthetic patches. This report describes three patients in whom delayed bleeding through needle holes along the suture lines in polytetrafluoroethylene cardiovascular patches occurred between 1.5 and 4 days after operation. All patients required reexploration to control bleeding, and acute respiratory distress from tracheal compression developed in one patient. Although delayed bleeding through needle holes in polytetrafluoroethylene cardiovascular patches appears to be rare, a word of caution may be in order before advocating routine patching of the carotid artery with this particular type of patch.

Aged↗

PubMed1992

Conventional versus high-porosity polytetrafluoroethylene grafts: clinical evaluation.

In baboons, nonreinforced (unwrapped) 60 microns internodal distance polytetrafluoroethylene grafts form a complete endothelial lining within 2 weeks by capillary ingrowth through the wall. Smooth muscle cells then grow under the endothelium and proliferate to form a complete neointima. To determine if spontaneous endothelialization of these grafts can also occur in humans, 10 above-knee femoropopliteal grafts composed of equal lengths of 60 and 30 microns polytetrafluoroethylene were placed in eight patients. These grafts were reinforced (wrapped) for human use. Because biopsy of the grafts was not possible, endothelialization was assessed noninvasively by 111In-labeled platelet imaging 1 week and 3 months after surgery. There was no difference in indium uptake between 60 and 30 microns segments at either time. Histologic sections were available from 60 microns segments of two patients who underwent operation for graft thrombosis. Capillary ingrowth was seen in these grafts, but it rarely extended more than half the distance from the outside of the graft to the lumen. Smooth muscle cells were not seen on the flow surface, indicating that a neointima had not formed. These findings demonstrate that capillary ingrowth can occur in 60 microns grafts in humans but does not produce an endothelial lining. The failure to endothelialize is perhaps a result of inadequacy of angiogenesis in adult humans or retardation of capillary ingrowth by the reinforcing wrap.

Aged↗

PubMed1992

Permanent lip augmentation employing polytetrafluoroethylene grafts.

There is a paucity of literature regarding aesthetic enhancement of the lips. This is due to the lack of reliable techniques employing autogenous tissue and the reluctance on the part of surgeons to use an alloplastic implant in this anatomic region, which is superficial, subject to trauma, and must conform to innumerable geometric shapes. The ideal lip augmentation procedure should provide for a predictable, permanent enlargement without visible scars or donor-site deformity, can be customized to the particular patient's anatomy, and can be reversed if so desired. A series of 21 alloplastic lip implants employing polytetrafluoroethylene with a mean follow-up of 14.33 months is presented. The overall complication rate was 9.52 percent. Permanent lip augmentation can be achieved with alloplastic sheet grafts of polytetrafluoroethylene in a safe and predictable fashion. Stiffness of the lips develops with progressive thickness of the grafts. Grafts exceeding 3 mm in thickness should be avoided.

Adolescent↗

PubMed1992

Prospective clinical study with in vitro endothelial cell lining of expanded polytetrafluoroethylene grafts in crural repeat reconstruction.

A nonrandomized prospective clinical study was undertaken to evaluate the technique and efficacy of in vitro endothelial cell lining of synthetic grafts. Twenty-six patients (10 men and 16 women with a mean age of 68.4 years; range, 49 to 80 years) with end stage chronic peripheral vascular disease requiring reoperation were entered into the study. In 13 patients venous endothelial cells were harvested 4 to 7 weeks before operation, grown to confluency in culture flasks, and seeded onto the inner surface of expanded polytetrafluoroethylene grafts. Thirteen patients received untreated expanded polytetrafluoroethylene grafts and served as a control. A scoring system with use of intraarterial angiography was used to assess disease severity. No statistically significant differences in angiographic score were seen between the two groups, indicating comparable severity of disease. Early secondary graft patency (0 to 30 days) was 92% for the in vitro endothelial cell lining group and 53% for control patients. The amputation rate after 18 months for the in vitro endothelial cell lining group was 15%, with a 31% rate in the control group. The functional performance of the in vitro endothelial cell lining bypasses was superior to that of untreated bypass grafts during the observed follow-up period. These early results suggest that in vitro endothelial cell lining is a method that can reduce the early occlusion rate now seen after repeat reconstruction of crural vessels.

Aged↗

PubMed1979

Expanded microporous polytetrafluoroethylene as a vascular substitute: a two year follow-up.

Since 1974, 131 femoropopliteal, distal popliteal, and tibial bypasses have been performed using expanded microporous polytetrafluoroethylene (PTFE). Forty patients were operated on for limb salvage, and 21 had had previous bypass procedures. The overall patency rate was 82%. Early occlusions possibly were related to technical error, but most probably were due to severity of disease and poor runoff. Late occlusions were related to progressive atherosclerosis in the proximal or distal arterial tree. A 75.7% cumulative patency rate was noted at 28 months. In man the PTFE prosthesis demonstrates a smooth intimal lining with fibroblastic ingrowth into the interstices of the graft. These results are considered to be excellent in this high-risk patient population. The patency rates achieved with PTFE are better than those accomplished with alternative conduits and approach the patency rates reported with autogenous saphenous vein. Expanded microporous polytetrafluoroethylene with its high patency, pliability, and tissue incorporation is an excellent arterial substitute. Only with continued use of this material and a more uniform patient selection can more equitable comparisons be made between expanded PTFE and the autogenous vein.

Adult↗

PubMed1978

Evaluation of polytetrafluoroethylene-graphite-coated total hip prostheses in goats.

This study was designed to determine if a porous polytetrafluoroethylene-graphite coating could furnish long-term stabilization of total hip prostheses. Prostheses were surgically implanted in 12 mature goats, which were observed postoperatively for as long as 1 year. Effective stabilization occurred in only 4 animals. Poor results in the other animals were attributed to lack of stabilization of the prostheses following initial implantation, which allowed movement at the interface between bone and polytetrafluoroethylene-graphite.

Animals↗

PubMed1976

Small vessel replacement with gore-tex (expanded polytetrafluoroethylene).

Conduits of expanded, fibrillated polytetrafluoroethylene (PTFE [Gore-tex]) have been evaluated as small vessel prostheses in dogs during a 6-month period. A configuration of high porosity and low density, long fibril Gore-tex was found to yield the best patency in canine arteries (femoral and carotid) and veins (femoral) as compared with more dense, less porous PTFE with shorter fibrils. Host tissue reaction showed minimal inflammation, excellent infiltration, and formation of a smooth neointima, which suggested satisfactory acceptance of the prosthesis.

Animals↗

PubMed1978

Expanded microporous polytetrafluoroethylene as canine arterial bypass or replacement graft.

Expanded microporous polytetrafluoroethylene (PTFE) has been used experimentally and clinically for small-vessel bypass or replacement grafting; the results vary widely. This study assessed short (4--cm) femoral and carotid artery replacement PTFE grafts and longer (12--cm) femoral artery bypass PTFE grafts that crossed a flexion crease. Pore size at the blood-graft interface ranged from 10 to 30 mu. At the end of three months, overall patency rate was 22%. No long bypass grafts remained patent. The pore size and type of anastomosis did not affect patency. The occlusion was always thrombotic, associated with fibrin at the suture line. Nine of the 20 short carotid grafts (45%) and five of 22 short femoral grafts (22%) remained patent. These poor results indicate that further experimental studies are needed before PTFE is used clinically when an alternative exists.

Animals↗

PubMed1979

The expanded polytetrafluoroethylene graft. Three years' experience with 362 grafts.

A total of 362 polytetrafluoroethylene (PTFE) grafts were implanted in patients as vascular substitutes in a variety of vascular reconstructive procedures. A total of 184 were used in femoropopliteal bypass operations. Cumulative patency rates showed 74% patency at the end of the first year of observation and 58% after two and three years. Seventeen grafts were used for femorotibial bypasses, with a cumulative patency rate of 40.4% after one year. Ninety-eight grafts were implanted in the upper or lower extremity to serve as vascular access for hemodialysis. For this group, the cumulative one-year patency rate was 83%. Sixty-three additional grafts were implanted in various other anatomic locations. Based on this experience, the PTFE graft seems to be a promising and versatile vascular prosthesis, although it should be used cautiously.

Aged↗

PubMed1979

Physical characteristics of implanted polytetrafluoroethylene grafts: a preliminary report.

Despite the widespread clinical use of polytetrafluoroethylene (PTFE) grafts, few reports dealing with their physical properties have appeared in the literature. In the past 20 months, 17 such grafts have been implanted into 15 patients threatened with limb loss, with an 88% immediate graft patency. Postoperatively, all patients underwent periodic evaluations; arteriograms were obtained in four. The effect of knee flexion on graft function was also studied. All grafts were found capable of withstanding cuff pressures in excess of 300 mm Hg without occlusion. With 90 degrees flexion, the grafts kinked crossing the knee joint but a pressure gradient or decrease in pulsatile blood flow did not develop. This remarkable resistance to external compression should render these grafts especially valuable for extra-anatomic bypass.

Aged↗

PubMed1979

Early failure of expanded polytetrafluoroethylene in femoral vein replacement.

Grafts of expanded 30-mu fibril length polytetrafluoroethylene (PTFE) were inserted as segmental femoral vein replacements in nine dogs. The contralateral femoral vein served as a control, receiving a graft from each dog's right external jugular vein. Graft patency was monitored for 24 weeks postoperatively with serial venograms and venous pressures of the operated limbs. All expanded PTFE grafts and one autogenous graft thrombosed within 24 to 48 hours. Significant venous hypertension in the extremities receiving the PTFE grafts persisted for six months.

Animals↗