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At least 19 recordsLinked to original sources
PubMed1997

Polytetrafluoroethylene giant granuloma and adenopathy: long-term complications following subureteral polytetrafluoroethylene injection for the treatment of vesicoureteral reflux in children.

PURPOSE: The use of polytetrafluoroethylene as bulking agent for the endoscopic treatment of vesicoureteral reflux in children has raised many concerns about the implant histocompatibility and the risk of migration of polytetrafluoroethylene particles. We report on 3 cases of long-term complications following subureteral polytetrafluoroethylene injection (STING) and an extensive review of the literature is presented. MATERIALS AND METHODS: Between January 1993 and December 1995, 3 children (2 males, 1 female; 4, 7 and 6 years old), previously submitted to STING, underwent open surgery for recurrent vesicoureteral reflux. RESULTS: In 1 case a hard nodular mass, strictly adherent to the ureteral wall, was a foreign body giant granuloma. All patients demonstrated a heavy multinucleated foreign body reaction around polytetrafluoroethylene particles in the pelvic nodes. CONCLUSIONS: Many experimental studies and some clinical observations have demonstrated that polytetrafluoroethylene particles elicit a foreign body granulomatous reaction and have the tendency to migrate. Until the long-term effects of their presence are well known, STING should be carefully evaluated in children and young patients.

Child↗
PubMed2003

A polyurethane vascular access graft and a hybrid polytetrafluoroethylene graft as an arteriovenous fistula for hemodialysis: comparison with an expanded polytetrafluoroethylene graft.

AIM: We evaluated a polyurethane vascular access graft (TVAG), a hybrid polytetrafluoroethylene graft (hPTFEG), and an expanded polytetrafluoroethylene graft (ePTFEG) for postoperative complications and graft patency in their use as prosthetic devices of vascular access for hemodialysis. METHODS: Between August 1993 and October 2001, we treated 200 patients in whom A-V fistulas were placed by the same surgeon. These were divided into the following four groups according to the type of blood access: 27 cases of ePTFEG, 23 cases of TVAG, 22 cases of hPTFEG, and 128 cases of an autogenous A-V fistula. We calculated the cumulative patency rates by the Kaplan-Meier method, including primary (problem-free) and secondary (revised or functional) patency rates. RESULTS: The hPTFEG group experienced few thromboses. The absence of perigraft edema in the TVAG group permitted the early use of the TVAG within a few postoperative days for hemodialysis. Among the three graft groups, the primary patency was the best in the hPTFEG group (94.7% at 1 year and 86.1% at 2 years), with a significant difference versus the ePTFEG group. In regard to secondary patency, hPTFEG had an excellent patency of 100% at 1 year and 90.9% at 2 years, and TVAG had a comparable patency with that of ePTFEG. CONCLUSION: The hPTFEG was considered superior to ePTFEG in terms of being complication-free and had the excellent 2 year secondary patency of 90.9%. TVAG, with a patency equal to that of ePTFEG, could be used immediately after implantation due to the absence of limb edema.

Arteriovenous Shunt, Surgical↗
PubMed2003

Randomized evaluation of polytetrafluoroethylene-covered stent in saphenous vein grafts: the Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts (RECOVERS) Trial.

BACKGROUND: Treatment of lesions located in saphenous vein grafts (SVGs) is associated with increased procedural risk and a high rate of restenosis. METHODS AND RESULTS: We conducted a randomized, multicenter trial to evaluate the usefulness of a polytetrafluoroethylene (PTFE)-covered stent compared with a bare stainless steel (SS) stent for prevention of restenosis and major adverse cardiac events (MACE) in patients undergoing SVG treatment. The primary end point was angiographic restenosis at 6 months. Secondary end points were 30-day and 6-month MACE rates, defined as the cumulative of death, myocardial infarction (MI), and target lesion revascularization. Between September 1999 and January 2002, 301 patients with SVG lesions were randomized to either the PTFE-covered JoStent coronary stent graft (PTFE group, n=156) or the SS JoFlex stent (control group, n=145). Angiographic and procedural success rates were similar between the 2 groups (97.4% versus 97.9% and 87.3% versus 93.8%, respectively). The incidence of 30-day MACE was higher in the PTFE group (10.9% versus 4.1%, P=0.047) and was mainly attributed to MI (10.3% versus 3.4%, P=0.037). The primary end point, the restenosis rate at 6-month follow-up, was similar between the 2 groups (24.2% versus 24.8%, P=0.237). Although the 6-month non-Q-wave MI rate was higher in the PTFE group (12.8% versus 4.1%, P=0.013), the cumulative MACE rate was not different (23.1% versus 15.9%, P=0.153). CONCLUSIONS: The study did not demonstrate a difference in restenosis rate and 6-month clinical outcome between the PTFE-covered stent and the SS stent for treatment of SVG lesions. However, a higher incidence of nonfatal myocardial infarctions was found in patients treated with the PTFE-covered stent.

Adult↗
PubMed2004

Patency rates and complications of Exxcel yarn-wrapped polytetrafluoroethylene grafts versus Gore-tex stretch polytetrafluoroethylene grafts: a prospective study.

PURPOSE: Polytetrafluoroethylene (PTFE) has long been used for hemodialysis access when there is no suitable superficial vein. We conducted a prospective randomized study to compare two PTFE grafts; the stretch Gore-tex graft and the Exxcel graft. METHODS: Between May 2000 and February 2001, PTFE grafts were implanted for hemodialysis access in the upper extremities of 94 consecutive patients with end-stage renal disease. Graft selection was randomized, with patients receiving either a Gore-tex or an Exxcel graft. All grafts were monitored for signs of thrombosis or other complications. Graft survival was analyzed using a life-table analysis and the log-rank test was applied to compare graft patency. RESULTS: The primary patency rates 1 and 2 years after implantation were 51% and 36% for the Exxcel grafts, and 71% and 45% for the Gore-tex grafts, respectively. The difference between the two groups was not significant at any time. The incidence of complications needing further surgical management was 8.2% in the Exxcel group and 6.7% in the Gore-tex group, without a significant difference. CONCLUSION: Exxcel grafts or Gore-tex stretch grafts can be used for dialysis access with similar expected outcomes for up to 2 years, despite the differences in their outer surface design. The yarn-wrapped design does not appear to enhance the graft patency and we found no remarkable difference.

Arteriovenous Shunt, Surgical↗
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↗
PubMed1999

Permanent implantation of expanded polytetrafluoroethylene is safe for pelvic surgery. United States Expanded Polytetrafluoroethylene Reproductive Surgery Study Group.

Clinical trials have shown the expanded polytetrafluoroethylene (ePTFE) membrane to be a highly effective adhesion barrier in gynaecological reconstructive surgery, but the material has not gained wide acceptance because of uncertainty about long-term safety. We conducted a prospective, observational multicentre study to determine if permanent implantation of the ePTFE membrane in the pelvis caused any adverse effects. The subjects were 146 women in whom the membrane was implanted permanently during peritoneal reconstruction in 1991-1996. Postoperatively, patients were examined at regular intervals. The mean postoperative observation time was 3.5 years. No long-term complications occurred. There were 10 births by Caesarean section and 12 by vaginal delivery. All of the pregnancies before these 22 births were uneventful, including 10 in which the women had uterine implantation sites. There were two ectopic pregnancies and three spontaneous abortions. Since the primary purpose of the study was to evaluate the long-term safety of ePTFE, early second-look laparoscopy was not performed routinely. Nevertheless, 24 women had a subsequent operation. Adhesions were present at 8/21 of the membrane sites in these women, a significant decrease compared with adhesions at 17/21 sites during the initial procedure (P = 0.005). This large, multicentre study confirmed the long-term safety of the ePTFE membrane in pelvic reconstruction. Removal of the barrier is not necessary.

Adult↗
PubMed1996

Comparison of survival of an expanded polytetrafluoroethylene graft designed for early cannulation to standard wall polytetrafluoroethylene grafts.

BACKGROUND: Placement and maintenance of a well-functioning vascular access are essential for delivery of adequate hemodialysis. Newly placed polytetrafluoroethylene (PTFE) arteriovenous grafts require a period of wound healing and incorporation of fibrous tissue before use, a period typically lasting two to three weeks. An ideal PTFE graft would be one that can be used for vascular access immediately, obviating the need for temporary dialysis catheters. Recently an expanded PTFE (ePTFE) graft with a mesh cannulation segment (Diastat graft) has been proposed for early cannulation. STUDY DESIGN: This is a retrospective single-center study comparing ePTFE graft survival to contemporaneously placed standard wall PTFE (GORE-TEX) grafts. RESULTS: Forty-seven consecutive new or established patients receiving chronic hemodialysis had grafts (25 ePTFE, 22 standard PTFE) placed between November 1994 and July 1995. There were no significant differences between the groups in age, race, gender, incidence of diabetes mellitus, or peripheral vascular disease. By the end of the study, 21 of 25 ePTFE grafts had clotted, compared with 11 of the 22 patients receiving a standard PTFE graft. Median time to first clotting was 53 days for the ePTFE grafts and 164 days for the standard PTFE grafts (p < 0.0001). Nine patients with ePTFE grafts required a temporary catheter after their first clotting episode. CONCLUSIONS: The ePTFE grafts thrombosed at a significantly higher rate than standard wall PTFE grafts. Further experience with the Diastat graft might improve graft survival. However, early experience does not suggest that the avoidance of short-term temporary access outweighs the problem of high clotting rate, and its attendant morbidity.

Arteriovenous Shunt, Surgical↗
PubMed2004

Multicenter randomized prospective trial comparing a pre-cuffed polytetrafluoroethylene graft to a vein cuffed polytetrafluoroethylene graft for infragenicular arterial bypass.

Poor patency of synthetic grafts for infragenicular revascularization has led to use of distal vein patches or cuffs. The aim of this study was to compare the distally widened Distaflo PTFE graft, which mimics a vein cuff, with a PTFE graft with distal vein modification. In this prospective, randomized, multicenter trial we compared use of a precuffed PTFE graft wit that of PTFE grafts with distal vein modification for infragenicular revascularization in patients with critical limb ischemia without saphenous vein. Study end points were primary and secondary patency and limb salvage rates at 2 years. From January 28,1999 to November 1, 2000, 104 patients were enrolled in 10 North American centers. Thirteen were excluded for protocol violation. Ninety-one bypasses were performed in 89 patients with a mean age of 73 years (range 47-90). By randomization, 47 bypasses were done with the precuffed graft and 44 with PTFE graft with vein cuff. Both groups were comparable for comorbidities and operative variables, except for a higher incidence of acute ischemia in the precuffed group (19% vs. 4.5%, p = 0.03). Bypass was a redo procedure in 53% and was performed at the infrapopliteal vessels in 79%. Operative mortality was 2.2% (2/91). Mean follow-up was 14 months (range 1-30). At 1 and 2 years, primary patency was 52% and 49% for the precuffed group and 62% and 44% for the vein cuffed group, respectively (p = 0.53). At 1 year and 2 years, the limb salvage rate was 72% and 65% for the precuffed group and 75% and 62% in the vein cuffed group (p = 0.88). Although numbers are small and follow-up short, this midterm analysis shows similar results for the Distaflo precuffed grafts and PTFE grafts with vein cuff. A precuffed graft is a reasonable alternative conduit for infragenicular reconstruction in the absence of saphenous vein and provides favorable limb salvage.

Aged↗
PubMed1991

Prospective, randomized comparison of ringed and nonringed polytetrafluoroethylene femoropopliteal bypass grafts: a preliminary report.

Kinking and compression with knee flexion are thought to be one cause of failure of below-knee polytetrafluoroethylene femoropopliteal bypass. To prevent this problem polytetrafluoroethylene grafts externally supported with rigid rings have been developed. The present randomized, prospective study compared ringed and nonringed polytetrafluoroethylene grafts in 122 patients who underwent femoropopliteal bypass for severe limb ischemia. Patients were well matched for surgical indications and risk factors. There was no significant difference in the 3-year graft patency rate of ringed versus nonringed polytetrafluoroethylene femoropopliteal bypasses (74% vs 68%, p = 0.5). Similarly, no significant differences were found in the 3-year graft patency rates of ringed versus non-ringed above-knee (82% vs 74%, p = 0.5) or below-knee polytetrafluoroethylene femoropopliteal bypasses (68% vs 59%, p = 0.5). The 3-year graft patency rate of all above-knee polytetrafluoroethylene femoropopliteal bypasses was slightly greater than that of below-knee polytetrafluoroethylene femoropopliteal bypasses (76% vs 62%), but this difference was not statistically significant (p = 0.25). The 3-year limb salvage rate with ringed polytetrafluoroethylene grafts was 92% compared with 79% for nonringed polytetrafluoroethylene grafts, but this difference was not statistically significant (p = 0.25). Data to date from this study fail to support the recommendation that ringed polytetrafluoroethylene grafts be used preferentially over conventional polytetrafluoroethylene grafts in patients who require femoropopliteal bypass with a synthetic graft.

Adult↗
PubMed1991

Adhesion of endothelial cells and adsorption of serum proteins on gas plasma-treated polytetrafluoroethylene.

From in vitro experiments it is known that human endothelial cells show poor adhesion to hydrophobic polymers. The hydrophobicity of vascular prostheses manufactured from Teflon or Dacron may be the reason why endothelialization of these grafts does not occur after implantation in humans. We modified films of polytetrafluoroethylene (Teflon) by nitrogen plasma and oxygen plasma treatments to make the surfaces more hydrophilic. Depending on the plasma exposure time, modified polytetrafluoroethylene surfaces showed water-contact angles of 15-58 degrees, versus 96 degrees for unmodified polytetrafluoroethylene. ESCA measurements revealed incorporation of both nitrogen- and oxygen-containing groups into the polytetrafluoroethylene surfaces, dependent on the plasma composition and exposure time. The thickness of the modified surface layer was approximately 1 nm. The adhesion of cultured human endothelial cells from 20% human serum-containing culture medium to modified polytetrafluoroethylene surfaces with contact angles of 20-45 degrees led to the formation of a monolayer of cells, which was similar to the one formed on tissue culture polystyrene, the reference surface. This was not the case when endothelial cells were seeded upon unmodified polytetrafluoroethylene. Surface-modified expanded polytetrafluoroethylene prosthesis material (GORE TEX soft tissue) also showed adhesion of endothelial cells comparable to cell adhesion to the reference surface. The amounts of serum proteins, including fibronectin, adsorbed from serum-containing medium to modified polytetrafluoroethylene surfaces were larger than those adsorbed to unmodified polytetrafluoroethylene. Moreover, the modified surfaces probably allow the exchange of adsorbed serum proteins with cellular fibronectin.

Adsorption↗
PubMed1994

Particles found in lung and brain following subureteral injection of polytetrafluoroethylene paste are not teflon particles.

We injected 0.3 ml. of polytetrafluoroethylene paste (Polytef) behind the left submucosal ureter in 4 mini-pigs and 4 dogs, and 2 dogs and 2 mini-pigs underwent sham operation and acted as controls. Two mini-pigs were injected with 0.5 ml. polytetrafluoroethylene (Teflon) suspended in 50 ml. of normal saline into a peripheral vein and 2 dogs were injected with 0.5 ml. polytetrafluoroethylene into a bladder vein. In addition, 4 dogs were injected with 0.1 ml. polytetrafluoroethylene paste suspended in 20 ml. saline into the right carotid artery. The lungs and brain from half of the animals who had subureteral and intravascular injection of polytetrafluoroethylene paste as well as sham operated animals were dissolved in sodium hypochlorite solution. The resulting organ suspensions were then centrifuged and the smear preparations of the precipitate were examined by polarized light microscopy, scanning electron microscopy and x-ray microanalysis. Polytetrafluoroethylene paste suspended in saline acted as positive control for polytetrafluoroethylene particles. Lungs and brain from the remaining animals were fixed in formalin solution. The brain and lungs of animals who underwent subureteral injection with a minimal amount of polytetrafluoroethylene paste carefully placed in the submucosal plane showed no evidence of polytetrafluoroethylene on histological examination, polarized light microscopy, scanning electron microscopy and x-ray microanalysis.

Animals↗
PubMed2000

A prospective randomized trial comparing vein with polytetrafluoroethylene in above-knee femoropopliteal bypass grafting.

OBJECTIVE: Despite many clinical studies, there is still uncertainty as to whether venous material is superior to polytetrafluoroethylene for femoropopliteal reconstruction proximal to the knee joint. Supported by early satisfactory results with thin-walled, stretched polytetrafluoroethylene for suprageniculate bypass grafts, a prospectively randomized clinical trial was designed to evaluate the effectiveness of reversed saphenous vein in comparison with that of polytetrafluoroethylene in above-knee arterial reconstruction. METHODS: In a 3-year period, 151 above-knee femoropopliteal bypass graft operations were performed in 136 patients (77 male, 59 female). The indication for operation was severe claudication in 120 cases, rest pain in 20 cases, and ulceration in 11 cases. For the bypass graft, a reversed saphenous vein was used in each of 75 cases, and a polytetrafluoroethylene prosthesis was used in each of 76 cases. Preoperative risk factors were diabetes (24%), a history of myocardial infarction (23%), and current status with respect to smoking (74%). There was no hospital mortality; 5% of patients had minor postoperative complications. RESULTS: After 2 years, the primary patency was 83% for saphenous vein and 67% for polytetrafluoroethylene (P =.065); the secondary patency was 83% for saphenous vein and 77% for polytetrafluoroethylene (P =.298). During a follow-up period of 2 years, we found no statistically significant difference in primary and secondary patency between saphenous vein and polytetrafluoroethylene. We found no predictive factor for occlusion of either bypass graft. CONCLUSION: The use of polytetrafluoroethylene above the knee is a reasonable alternative in femoropopliteal bypass grafting that is associated with acceptable short-term patency rates.

Anastomosis, Surgical↗
PubMedDate not supplied

Healing characteristics of hybrid and conventional polytetrafluoroethylene vascular grafts.

The concepts of porosity and healing in vascular grafts are interrelated. The initial phase of healing includes cellular infiltration into the prosthesis followed by tissue ingrowth from perigraft sources. This provides a framework for development of a pseudointima. The microstructure of conventional expanded polytetrafluoroethylene grafts with an average internodal distance of 20 microns or less results in hindered cellular penetration and tissue ingrowth. A new microstructure hybrid polytetrafluoroethylene graft is described that has a high porosity 60 microns average internodal distance on the adventitial surface combined with a fine pore 20 microns average internodal distance on the luminal surface. In addition, tapered through-pore channels provide a direct channel from the adventitia and lumen that allow biologic communication to occur where cells and tissue can penetrate and vaginate. Canine carotid and femoral implant studies were performed to elucidate healing effects of polytetrafluoroethylene graft structure on cellular penetration and tissue ingrowth. Enhanced cellularity and tissue ingrowth were observed in hybrid polytetrafluoroethylene implants compared to implants of conventional expanded polytetrafluoroethylene. Human explants also demonstrate enhanced initial cellular penetration and capillary formation in the hybrid polytetrafluoroethylene graft wall. It is postulated that hybrid polytetrafluoroethylene will result in improved clinical performance as a result of removal of the healing restrictions associated with random microstructure conventional expanded polytetrafluoroethylene vascular grafts.

Aged↗
PubMed1998

Multicenter survey of endoscopic treatment of vesicoureteral reflux using polytetrafluoroethylene.

PURPOSE: Endoscopic subureteral polytetrafluoroethylene (Teflon) injection has been used successfully to treat primary and secondary vesicoureteral reflux in children. We review the results of subureteral polytetrafluoroethylene injection in terms of its effectiveness, long-term followup and morbidity. MATERIALS AND METHODS: A total of 53 pediatric urologists and/or pediatric surgeons at 41 centers worldwide answered an inquiry regarding experience with subureteral polytetrafluoroethylene injection in vesicoureteral reflux. Data were collected from a completed standard questionnaire. From 1984 to 1996, 1,921 boys and 6,411 girls with a mean age of 4.5 years (12,251 refluxing ureters) were treated endoscopically with subureteral polytetrafluoroethylene injection. Reflux was grades I to V in 407 (3.3%), 3,832 (31.2%), 5,213 (42.5%), 2,218 (18.1%) and 581 (4.7%) ureters, respectively. In the majority of patients subureteral polytetrafluoroethylene injection was performed on an outpatient basis. Most urologists monitored patients with voiding cystourethrography and renal ultrasound at 3 months, 1 year and 3 years. All patients were followed 1 to 13 years. RESULTS: Reflux resolved in 9,226 ureters (75.3%) after 1 polytetrafluoroethylene injection, in 1,478 (12%) after 2 and in 250 (2%) after 3 or 4. Vesicoureteral reflux improved to grade I after 1 or 2 injections in 743 (6%) ureters, which needed no further treatment. Subureteral injection failed to correct reflux in 554 ureters (4.5%), which were then treated with ureteral reimplantation. Vesicoureteral junction obstruction requiring ureteral reimplantation developed in 41 ureters (0.33%). More than 90% of patients have been followed for more than 2 years. At followup reflux recurred in 326 (2.8%) endoscopically corrected refluxing ureters. No clinically untoward effects were reported in any patient due to the use of polytetrafluoroethylene as an injectable material. CONCLUSIONS: The results of this multicenter survey confirm that endoscopic subureteral polytetrafluoroethylene injection is a simple, safe and effective outpatient procedure for treating all grades of vesicoureteral reflux.

Adolescent↗
PubMedDate not supplied

Comparison of the polyvinyl alcohol sponge and expanded polytetrafluoroethylene subcutaneous implants as models to evaluate wound healing potential in human beings.

Our current understanding of the complex processes involved in wound healing is based mainly on studies of animal models. Although this information has been useful, it may not totally reflect the response found in human beings. For example, human beings have a tendency to either "overheal," as seen in keloids and hypertrophic scar formation, or have deficient healing, as seen in chronic ulcer formation. No animal models are available to analyze these human clinical pathologic conditions. Therefore the objective of this study was to analyze the wound healing response in a large population (n = 40) of normal healthy human beings as a first step to begin studies of abnormal human wound healing. Simultaneously, a comparison was made between the polyvinyl alcohol implant and the expanded polytetrafluoroethylene implant model. Under sterile conditions with the use of local anesthesia, two preweighed polyvinyl alcohol implants and two standard 6 cm expanded polytetrafluoroethylene implants were placed subcutaneously in the upper arm of each subject. High-performance liquid chromatography was used to quantitate isoleucine and hydroxy-l-proline in acid hydrolysates of each implant. Isoleucine was used as an indicator of protein content in the tissue sample, whereas hydroxyproline reflected collagen content. No infectious or hemorrhagic complications were found in the 40 volunteers included in the study. No significant difference was found in isoleucine or hydroxy-l-proline content between postoperative day 7 polyvinyl alcohol implants and day 14 polyvinyl alcohol implants. In contrast, both isoleucine and hydroxy-l-proline content were significantly increased in day 14 expanded polytetrafluoroethylene implants compared with day 7 implants (p < 0.005 and p < 0.001, respectively). In addition, the ratio of hydroxy-l-proline to isoleucine was significantly increased in day 14 expanded polytetrafluoroethylene implants compared with day 7 expanded polytetrafluoroethylene and both day 7 and day 14 polyvinyl alcohol implants (p < 0.001). This observation suggests that by 14 days implantation of expanded polytetrafluoroethylene stimulated an increased deposition of collagen. No significant differences were found in the hydroxy-l-proline to isoleucine ratios among day 7 expanded polytetrafluoroethylene, day 7 polyvinyl alcohol, and day 14 polyvinyl alcohol implants. Histologic analyses correlated with the biochemical findings. These results suggest that expanded polytetrafluoroethylene may be the preferred implant for studies designed to examine pathologic processes associated with retarded wound healing. In contrast, the polyvinyl alcohol implant may be better suited for studies where a low background response is required. Moreover, the extreme variability in normal healthy volunteers seen in this study correlates clinically with the finding that, among the normal adult human population, there is a heterogeneous wound healing response.

Journal Article↗
PubMed2000

Clinical experience with autologous endothelial cell-seeded polytetrafluoroethylene coronary artery bypass grafts.

OBJECTIVE: Autologous endothelial cell seeding was used to improve the patency of 4-mm polytetrafluoroethylene vascular prostheses. METHODS: Since 1995, 14 patients with coronary artery disease received 21 autologous endothelial cell-seeded polytetrafluoroethylene vascular bypass grafts for coronary artery revascularization. The polytetrafluoroethylene grafts were seeded with the endothelial cells in a multiple step procedure, including cell culture techniques before coronary bypass operation. With the use of extracorporal circulation and cardioplegic arrest, a bypass operation was performed by means of conventional surgical techniques. RESULTS: After a mean postoperative follow-up of 27.7 months (range, 7.5-48 months), the graft patency rate is 90.5%. Follow-up angiograms of the aorta-coronary polytetrafluoroethylene bypass grafts showed patent bypasses in all cases except two. Angiograms of all 19 patent endothelial cell-seeded polytetrafluoroethylene bypass grafts showed a smooth luminal borderline without stenotic regions. The percutaneous transluminal angioscopic evaluation showed a glossy white and smooth endoluminal graft surface without any fibrin, platelet, or erythrocyte deposits. Intravascular ultrasonographic examinations confirmed the results. CONCLUSION: Patency of autologous endothelial cell-seeded 4-mm polytetrafluoroethylene vascular prostheses as coronary artery bypass grafts was much better than that of unseeded polytetrafluoroethylene grafts. Further evaluations and a larger population of patients will prove whether the encouraging patency will last.

Aged↗
PubMed2003

Vein versus polytetrafluoroethylene in above-knee femoropopliteal bypass grafting: five-year results of a randomized controlled trial.

OBJECTIVE: Controversy still exists whether polytetrafluoroethylene is equivalent to vein as bypass graft material for the above-knee femoropopliteal bypass. Therefore, a prospective randomized trial was performed to compare vein with polytetrafluoroethylene for femoropopliteal bypasses with the distal anastomosis above the knee. METHODS: Between January 1993 and December 1996, 151 above-knee femoropopliteal bypasses were performed. The indications for operation were severe claudication in 120 cases, rest pain in 20 cases, and ulceration in 11 cases. After randomization, 75 reversed saphenous venous bypasses and 76 polytetrafluoroethylene bypasses were performed. RESULTS: No perioperative mortality was seen, and 5% of the patients had minor infections of the wound, not resulting in loss of the bypass, the limb, or life. After 5 years, 38% of the patients had died and 7% were lost to follow-up. Only once was the saphenous vein necessary for coronary artery bypass grafting. Primary patency rates after 5 years were 75.6% for venous bypass grafts and 51.9% for polytetrafluoroethylene grafts (P =.035). Secondary patency rates were 79.7% for vein and 57.2% for polytetrafluoroethylene bypasses (P =.036). In the venous group, 14 bypasses failed, leading to five new bypasses. In the polytetrafluoroethylene group, 29 bypasses failed, leading to 16 reinterventions. For these 16 new bypasses, in four cases, the ipsilateral preserved saphenous vein was used. In both groups, one above-knee amputation and one below-knee amputation had to be performed. CONCLUSION: We conclude after 5 years of follow-up of this randomized controlled trial that a bypass with saphenous vein has better patency rates at all intervals and needs fewer reoperations. Saphenous vein should be the graft material of choice for above-knee femoropopliteal bypasses and should not be preserved for reinterventions. Polytetrafluoroethylene is an acceptable alternative if the saphenous vein is not available.

Arterial Occlusive Diseases↗
PubMed1985

Externally stented polytetrafluoroethylene valved conduits for right heart reconstruction. An experimental comparison with Dacron valved conduits.

Valve-containing conduits have made possible the repair of many congenital anomalies that involve right ventricular-pulmonary arterial discontinuity. The distressing problem of neointimal peel formation with eventual conduit obstruction in patients with Dacron valved conduits has led to the need for premature replacement in many patients. Externally stented polytetrafluorethylene has demonstrated superior patency in the venous system experimentally and clinically and was believed to have potential advantages over Dacron for conduit construction. This study compares the transconduit resistance and the thickness of the neointimal peel in right ventricular-pulmonary arterial conduits constructed of externally stented polytetrafluoroethylene with those of woven Dacron. The 19 mm externally stented polytetrafluoroethylene conduits (Impra, Inc.) containing a Hancock porcine valve (Extracorporeal Inc.) were implanted in six adult mongrel dogs followed by proximal occlusion of the pulmonary artery. In six additional animals, a Dacron valved conduit of similar size and length was inserted. Cardiac output, transconduit gradient, and resistance were measured at operation and at 3 months. All conduits were subsequently explanted, opened longitudinally, and the thickness of the neointimal peel (excluding suture lines) measured. No hemodynamic differences were noted during the 3 month follow-up. However, the thickness of the neointimal peel was fourfold greater in Dacron conduits (609 +/- 144 mu) than in the conduits constructed of externally stented polytetrafluoroethylene (156 +/- 50 mu) (p less than 0.01). The thick peel in Dacron conduits extended into the outflow portion of the porcine valve cusps and prevented their full excision. The neointima in externally stented polytetrafluoroethylene conduits was thin and uniform and did not extend onto the leaflets or limit their mobility. This study demonstrated that the early hemodynamic performance of externally stented polytetrafluoroethylene conduits was comparable to that of Dacron conduits; Dacron conduits were subject to an accelerated rate of peel formation that affected leaflet mobility and may be a factor in early valve degeneration; a thin neointima formed in externally stented polytetrafluoroethylene conduits and valve leaflet motion was preserved. This study showed that externally stented polytetrafluoroethylene conduits offer advantages over Dacron valved conduits and warrant clinical application.

Animals↗