Polytetrafluoroethylene (PTFE), polyurethane (PU) and silicone are widely known biocompatible polymers which are commonly used for vascular grafts. However, in vitro and in vivo calcifications of these polymers have been found to seriously compromise their quality as biomaterials. In consideration of this problem, the present study compared the calcification rate and extent of PTFE, PU and silicone. Using the in vitro flow-type method, PTFE, PU and silicone films were tested for 1, 4, 7, 10, 14 and 21 days. After 21 days of in vitro calcification test, the calcium levels on PTFE, PU and silicone were 35.89 5.01 microgram /cm2, 23.73 0.68 microgram/cm2 and 19.86 5.28 microgram/cm2, respectively. The higher observed calcium level for PTFE may be due to the effect of the rough surface of PTFE in accumulating calcium ions on the polymer surface. From the 7th day of test, the [Ca]/[P] molar ratio started to decrease over time, and PTFE showed a faster calcification process. This decreasing [Ca]/[P] molar ratio demonstrated the typical calcification mechanism consisting of phosphorus ion accumulation following calcium ion accumulation. This study concluded that PU and silicone are less calcified than PTFE film, a finding in good agreement with previously published studies.
Biocompatible Materials/*adverse effects ; *Blood Vessel Prosthesis ; Calcinosis/*etiology ; Comparative Study ; Microscopy, Electron, Scanning ; Polytetrafluoroethylene/*adverse effects ; Polyurethanes/*adverse effects ; Silicones/*adverse effects

Aged ; Angioplasty, Balloon, Coronary ; adverse effects ; Coronary Vessels ; injuries ; Drug-Eluting Stents ; Humans ; Male ; Polytetrafluoroethylene ; chemistry ; therapeutic use

Expanded polytetrafluoroethylene(ePTFE) grafts 4mm long and 1mm in diameter were implanted into the iliac artery of 100-150g male rats using standard microvascular technique. Prior to clamp removal, the cremaster muscle was isolated as an island flap based on the iliac artery and observed using intravital fluorescence microscopy. Fields which contained a bifurcation of a first order arteriole(80-100 microns diameter) into second order arteriole(50-80 microns) were chosen for observation. Platelets were labeled in vivo with acridine red to visualize and quantify the aggregates. Images of microemboli were counted manually and the area was measured by computerized planimetry. Six control grafts were implanted with no further processing, six were irrigated with heparin, and six were coated with tridodecylmethylammonium chloride(TDMAC) and heparin. Most thrombi appeared within the first five minutes after implantation in all groups. The total number of emboli observed in the control group was 91 pr animal, in the heparin irrigation group it was 84, and in the TDMAC-heparin group it was 22. The total thrombus area observed per animal was 137,660 +/- 29,467 microns 2 in the control group, 79,040 +/- 10,893 microns 2 in the heparin irrigation group, and 17,498 +/- 6,059 microns 2 in the TDMAC-heparin group (p<.01 vs control or heparin irrigation group). With this results we could find that heparin irrigation and TDMAC-heparin coating appear to reduce the number, size, and total amount of microemboli generated by ePTFE graft implantation and apparent thromboresistant property of TDMAC-heparin coating may have widespread application in many clinical and research areas and this experimental model can be used for evaluation of other graft matrials.
Ammonium Compounds/pharmacology ; Animal ; Blood Vessel Prosthesis/*adverse effects ; Heparin/pharmacology ; Male ; Microcirculation/surgery ; Polytetrafluoroethylene/adverse effects ; Rats ; Thrombosis/*etiology/prevention & control

PURPOSE: Augmentation rhinoplasty using alloplastic materials is a relatively common procedure among Asians. Silicon, expanded polytetrafluoroethylene (Gore-tex(R)), and porous high density polyethylene (Medpor(R)) are most frequently used materials. This study was conducted to analyze revisional rhinoplasty cases with alloplastic materials, and to investigate the usage of alloplastic materials and their complications. We also reviewed complications caused by various materials used in plastic surgery while operating rhinoplasty. MATERIALS AND METHODS: We report 581 cases of complications rhinoplasty with alloplastic implants and review of the literature available to offer plastic surgeons an overview on alloplastic implant-related complications. RESULTS: Among a total 581 revisional rhinoplasty cases reviewed, the alloplastic materials used were silicone implants in 376, Gore-tex(R) in 183, and Medpor(R) in 22 cases. Revision cases and complications differed according to each alloplastic implant. CONCLUSION: Optimal alloplastic implants should be used in nasal structure by taking into account the properties of the materials for the goal of minimizing their complications and revision rates. A thorough understanding of the mechanism involved in alloplastic material interaction and wound healing is the top priority in successfully overcoming alloplastic-related complications.
Asian Continental Ancestry Group ; *Biocompatible Materials/adverse effects ; Humans ; Polyethylene ; Polyethylenes ; *Polytetrafluoroethylene ; Postoperative Complications ; Prosthesis Implantation/*methods ; Rhinoplasty/*methods ; Silicones ; Treatment Outcome

OBJECTIVE: To investigate the safety, efficacy and long-term patency of parallel shunts (PS) in the management of the transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. MATERIALS AND METHODS: Between March 2007 and October 2010, 18 patients (13 men and 5 women) who underwent TIPS revision with the creation of PS were evaluated retrospectively. In the first 10 patients, a 10-mm-diameter Wallgraft endoprosthesis was deployed; in the latter 8 patients, an 8-mm-diameter Fluency endoprosthesis was deployed. RESULTS: The creation of PS was technically successful in all patients. The mean +/- standard deviation portosystemic pressure gradient before and after the procedure was 25.5 +/- 7.3 mm Hg (range, 16-37 mm Hg) and 10.9 +/- 2.3 mm Hg (range, 7-16 mm Hg), respectively. The duration of follow-up was 16.7 +/- 10.8 months (range, 6-42 months). The primary shunt patency rates at 12 months after the creation of PS was 70% with Wallgraft endoprostheses and 87.5% with Fluency endoprostheses. CONCLUSION: TIPS revision with the creation of PS is a safe, effective and durable method for treating shunt dysfunction.
Adult ; Aged ; Blood Pressure Determination ; Female ; Humans ; Male ; Middle Aged ; Polytetrafluoroethylene ; Portasystemic Shunt, Transjugular Intrahepatic/adverse effects/*methods ; Prosthesis Design ; Reoperation/methods ; Retrospective Studies ; Stents

OBJECTIVE: To evaluate the safety and efficacy of unilateral covered stent placement in patients with malignant superior vena cava (SVC) syndrome. MATERIALS AND METHODS: Between October 2008 and November 2012, expanded polytetrafluoroethylene-covered stent placement for malignant SVC syndrome was performed in 40 consecutive patients (35 men and five women; mean age, 61.4 years; range, 35-81 years). All covered stents were unilaterally placed within the SVC or across the venous confluence when needed to relieve venous obstruction and prevent tumor overgrowth, regardless of patency of contralateral brachiocephalic veins. RESULTS: Stent placement was technically successful in all patients. There were no major complications. Of the 37 patients symptomatic prior to stent placement, 34 (92%) experienced complete symptomatic relief 1-8 days after stent placement. Of the 29 patients who underwent covered stent placement across the venous confluence, nine patients had patent contralateral brachiocephalic veins prior to stent placement. However, no sign of SVC obstruction or contralateral upper extremity venous thrombosis was observed during the follow-up period. Kaplan-Meier analysis revealed median patient survival of 163 days. Stent occlusion occurred in four (10%) of 40 patents. Cumulative stent patency rates at 1, 3, 6, and 12 months were 95%, 92%, 86%, and 86%, respectively. CONCLUSION: Unilateral covered stent placement appears to be a safe and effective method for treating malignant SVC syndrome, despite the location of SVC occlusion.
Adult ; Aged ; Aged, 80 and over ; Female ; Humans ; Kaplan-Meier Estimate ; Male ; Middle Aged ; *Polytetrafluoroethylene ; Retrospective Studies ; *Stents/adverse effects ; Superior Vena Cava Syndrome/etiology/mortality/*therapy ; Treatment Outcome

OBJECTIVETo assess the patency and complications of the polytetrafluoroethylene (PTFE) graft for hemodialysis access and to summarize the experiences in the treatment of graft occlusions.

METHODSThe clinical data of 30 patients who underwent forearm PTFE graft for hemodialysis access from March 2003 to December 2008 in our hospital were retrospectively analyzed.

RESULTSPatients were followed up for (28.7+/-17.6) months (range: 8-78 months).The peri-operative mortality was zero. Primary patency rate was 70.0% at Year 1 and 56.7% at Year 2. Accumulative secondary patency rate was 90.0% and 80.0%, respectively at Year 1 and Year 2. Postoperative complications included graft thrombosis (n=13, 43.3%), venous anastomosis stenosis (n=1, 3.3%), graft infection (n=2, 6.7%), and edema of the forearm (n=10, 33.3%). Totally 24 graft revisions were performed, including thrombectomy (12 times), thrombectomy and venous anastomosis plasty with artificial patch (4 times), arterial and venous anastomosis plasty with patch (2 times), venous anastomosis angioplasty with a balloon (2 times), new graft hemodialysis access construction in the contralateral arm (1 case), and graft removal (3 cases).

CONCLUSIONSPTFE graft is an important backup hemodialysis access in uremic patients. Proper revision according to different cause of graft occlusions can prolong the service time of the graft.

Adult ; Aged ; Aged, 80 and over ; Arteriovenous Shunt, Surgical ; adverse effects ; Blood Vessel Prosthesis ; Female ; Graft Occlusion, Vascular ; etiology ; therapy ; Humans ; Male ; Middle Aged ; Polytetrafluoroethylene ; Renal Dialysis ; Retrospective Studies

No abstract available.
Coated Materials, Biocompatible ; Esophageal and Gastric Varices/etiology/*surgery ; Humans ; Hypertension, Portal/etiology/*surgery ; Liver Cirrhosis/complications ; Polyesters ; Polytetrafluoroethylene ; Portasystemic Shunt, Transjugular Intrahepatic/*adverse effects ; Reoperation ; Stents/adverse effects ; Vascular Patency

OBJECTIVE: We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. MATERIALS AND METHODS: Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents. These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50-80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis. The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was 27.9 weeks (range: 2-81 weeks). RESULTS: Placement was successful in all cases. Seventy-six percent of the patients (28/37) experienced adequate palliative drainage for the remainder of their lives. There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD (percutaneous transhepatic biliary drainage) irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively. Stent insertion resulted in acute elevations of the amylase and lipase levels one day after stent insertion in 11 patients in spite of performing endoscopic sphincterotomy (4/6). The bilirubin levels were significantly reduced one week after stent insertion (p < 0.01). The 30-day mortality rate was 8% (3/37), and the survival rates were 49% and 27% at 20 and 50 weeks, respectively. The primary stent patency rates were 85%, and 78% at 20 and 50 weeks, respectively. CONCLUSION: The PTFE-covered self-expandable nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates.
Adenocarcinoma/*complications ; Aged ; Aged, 80 and over ; Alloys/adverse effects/*therapeutic use ; Cholestasis, Extrahepatic/etiology/*surgery ; Coated Materials, Biocompatible/*therapeutic use ; Common Bile Duct/radiography/surgery ; Digestive System Neoplasms/*complications ; Equipment Design ; Female ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Palliative Care/methods ; Pilot Projects ; Polytetrafluoroethylene/adverse effects/*therapeutic use ; Postoperative Complications/diagnosis/epidemiology ; Prospective Studies ; *Stents/adverse effects ; Survival Analysis ; Treatment Outcome

BACKGROUNDBalanced adjustment of the portal vein shunt volume during a transjugular intrahepatic portosystemic shunt (TIPS) is critical for maintaining liver perfusion and decreasing the incidence of liver insufficiency. A stent-graft is proved to be superior to a bare metal stent (BMS) for the construction of a TIPS. However, the clinical results of the combination application of stents and stent-grafts have not been determined. This study aimed to compare the technique of using a combination of stents and stent-grafts with using a single stent-graft to construct a TIPS.

METHODSFrom April 2011 to November 2014, a total of fifty patients were randomly assigned to a stents-combination group (Group I, n = 28) or a stent-graft group (Group II, n = 22). Primary patency rates were calculated. Clinical data, including the technical success rate, bleeding control results, incidence of encephalopathy, liver function preservation, and survival rate, were assessed.

RESULTSTechnically, the success rate was 100% for both groups. The primary patency rates at 1, 2, and 3 years for Group I were 96%, 84%, and 77%, respectively; for Group II, they were 90%, 90%, and 78%, respectively. The survival rates at 1, 2, and 3 years for Group I were 79%, 74%, and 68%, respectively; for Group II, they were 82%, 82%, and 74%, respectively. The incidence of hepatic encephalopathy was 14.3% for Group I and 13.6% for Group II. The Child-Pugh score in Group I was stable at the end of the follow-up but had significantly increased in Group II (t = -2.474, P = 0.022).

CONCLUSIONSThe construction of a TIPS with either the single stent-graft or BMS/stent-graft combination is effective for controlling variceal bleeding. The BMS/stent-graft combination technique is superior to the stent-graft technique in terms of hepatic function preservation indicated by the Child-Pugh score. However, considering the clinical results of the TIPS, the two techniques are comparable in their primary shunt patency, incidence of encephalopathy and patient survival during the long-term follow-up.

Aged ; Female ; Hepatic Encephalopathy ; diagnosis ; etiology ; Humans ; Hypertension, Portal ; complications ; mortality ; surgery ; Male ; Middle Aged ; Polytetrafluoroethylene ; Portal Vein ; surgery ; Portasystemic Shunt, Transjugular Intrahepatic ; adverse effects ; methods ; Postoperative Complications ; Prospective Studies ; Stents ; Treatment Outcome