Median Patency Duration Research Articles

Metallic Stents for Treatment of Benign Biliary Obstruction: A Long-term Study Comparing Different Stents

To investigate the role of metallic stents in the treatment of benign biliary strictures and analyze the differences in primary patency associated with the various types of stents deployed. Between 1990 and 1997, 21 patients with benign obstructive jaundice were treated with transhepatic placement of metallic stents (11 Wallstents in 10 patients, nine Palmaz stents in seven patients, and four tantalum Strecker stents in four patients). Nineteen patients presented with strictures not responding to balloon angioplasty (postsurgical, n = 13; cholangitis, n = 5; unknown, n = 1). Estimates for cumulative patency, patency rate in the different stent groups, and survival were calculated with use of life-table analysis; the log-rank test was used to compare the different stent groups. The prognostic relevance of the selected variables-stent type, stent length, etiology, and location-were modeled with respect to patency according to Weibull distribution. The median follow-up time was 80.5 months (range, 2-116 months). The median survival time was 91 months. One patient was lost to follow-up after 3 months. Repeat intervention for recurrent obstructive jaundice was necessary in 11 patients (55%), and the median patency rate was 26 months (range, 2-96 months). The Palmaz stent was the most effective in achieving long-term patency, with a median patency duration of 36 months (range, 22-96 months), versus 9 months (range, 3-67 months) for the Wallstent and 6 months (range, 2-15 months) for the tantalum Strecker stent. The cumulative patency rate with the Palmaz stent was significantly higher than for the tantalum Strecker stent (log-rank test, P = .017) and nonsignificantly higher compared with the Wallstent (log-rank test, P = .07). Multivariate analysis showed that the type of stent (Wald test, P = .003) and stent length (Wald test, P < .0001) influenced the patency rate. These results suggest that the type of stent and the stent length have a significant influence on the patency rate. In this series, the Palmaz stent was most effective in achieving long-term patency in benign biliary strictures.

Long Term Outcome of Biliary and Duodenal Stenting in Palliative Treatment of Patients with Unresectable Pancreatic Adenocarcinoma

Biliary stents are an effective method for palliation management of malignant biliary strictures. More recently, some studies have shown that duodenal stents provide safe and efficacious palliative options in duodenal stenosis. Currently, patients with unresectable pancreatic cancer have improved survival but the long term outcome of stents in such patients is not well-known. Aim : Evaluate the necessity, the feasibility and the long term effectiveness of stents in palliative treatment of biliary and duodenal obstruction. Patients and Methods : All consecutive patients with unresectable pancreatic cancer, seen between 01/99 and 09/03 were retrospectively studied. Patients with surgical bypass were excluded. All biliary and duodenal obstruction were reviewed. Evaluated outcomes included technical stent success,reobstruction and survival. Results : 144 patients (78 M, 66 F), median age 64 years (32-90)had unresectable pancreatic cancer - locally advanced (60%) or metastatic (40%)-. The actuarial median survival was 10 months (0,7-29,3) (metastatic : 8 months, locally advanced : 12 months). Biliary and duodenal stenosis occurred in 89% of patients with cancer of the pancreatic head and 19%, respectively after a median delay following diagnosis of 0,1 months (0-24,1) and 2,1 months (0-37,9), respectively. Biliary endoprosthesis were successfully placed in 74 patients (90%); remaining patients underwent a percutaneous procedure. When a self-expandable metallic stent was first inserted (n=59), a single stent was sufficient in 69% of cases (median duration of patency : 6,2 months (0,4-21,1). Duodenal stenting was successful in 26 patients (96%) and 92% of them required only one stent (median duration of patency : 5,7 months (0,5-15,7). Twenty one patients (15%) had either concomitant or metachronous development of biliary and duodenal obstruction. Combined stenting was successful in 89% of cases. No major complication or death occurred related to endoscopic treatment. Conclusion : With improved survival of patients with unresectable pancreatic cancer, about 90% and 20% of patients presented biliary and duodenal obstruction, respectively. The feasibility of biliary and duodenal stenting was excellent. During follow-up, 69% and 90% of patients required a single self-expandable metallic biliary and duodenal stents, respectively.

Malignant Biliary Obstruction: Treatment with ePTFE-FEP– covered Endoprostheses—Initial Technical and Clinical Experiences in a Multicenter Trial

To determine and present the initial technical and clinical results of using an expanded polytetrafluoroethylene-fluorinated ethylene propylene (ePTFE-FEP)-covered biliary endoprosthesis to treat malignant biliary obstruction. This prospective nonrandomized study included 42 patients with malignant obstruction of the common bile duct, common hepatic duct, and hilar confluence. Unilateral (n = 38) or bilateral (n = 4) bile duct drainage was performed by using fully covered endoprostheses with anchoring fins. To avoid branch duct blockage, endoprostheses with drainage holes at the proximal end were available. Procedure- and device-related complications were recorded. Patient survival and stent patency rates were calculated with Kaplan-Meier survival analysis. Mean follow-up bilirubin and alkaline phosphatase levels were calculated, and differences in means were evaluated with a paired t test. Successful deployment, correct positioning, and patency of the device were achieved in all patients. Procedure-related complications occurred in two (5%) patients. Thirty-day mortality rate was 20% (eight of 41 patients), and median survival time was 146 days. Laboratory values decreased significantly after the procedure (P <.001). Recurrent obstructive jaundice occurred in six (15%) patients. Primary patency rates at 3, 6, and 12 months were 90%, 76%, and 76%, respectively. Calculation of the composite end point of death or obstruction revealed a median patency duration of 138 days. No endoprosthesis migration was observed. Branch duct obstruction was observed in four (10%) patients. Postmortem examination of one stent revealed a widely patent endoprosthesis with intact covering. Initial results of percutaneous treatment of malignant biliary obstructions with fully covered ePTFE-FEP endoprostheses suggest that they are safe and potentially clinically effective.

Nonsurgically Placed Nasolacrimal Stents for Epiphora: Long-term Results and Factors Favoring Stent Patency

To evaluate long-term effectiveness of a polyurethane stent in lacrimal system treatment. Fluoroscopically guided placement of a polyurethane lacrimal stent was evaluated in 727 obstructed lacrimal systems in 588 patients with a mean follow-up period of 77 weeks (range, 1-277 wk), from which the technical and initial success rates and long-term patency were calculated. The impact of factors affecting long-term patency, including symptom duration, previous probing, presence of pus or eye discharge, lesion multiplicity, and site of obstruction were evaluated. Changes in 295 patients' lacrimal sac configuration after stent removal were analyzed and classified into three categories: contraction, widening, and no change. The overall technical success rate in this study was 95.9%, with a 90.8% initial clinical success rate. The median primary patency duration was 504.33 days plus minus 23.17; secondary median patency duration was 642.87 days plus minus 24.68. Most favorable factors such as symptom duration, previous probing, presence of pus, or eye discharge showed no significant difference; however, site of obstruction and lesion multiplicity influenced mean patency. Lesions below the junction and single lesions showed longer patency periods. Common canalicular obstruction after stent removal occurred in 50 (17%) lacrimal systems. Irregular sac configuration appeared in 171 (58%) lacrimal systems after stent removal. Sac configuration was the same in 185 (62.7%) lacrimal systems, contracted in 105 (35.6%), and widened in five (1.7%). In 151 eyes of 295, epiphora recurred 121.6 days (range, 1-1,182 d) after stent removal. Fluoroscopic lacrimal stent placement is a simple and safe outpatient procedure, but high recurrence and sac irregularities after stent removal are not encouraging.

Hydrostatic pressure reduces thrombogenicity of polytetrafluoroethylene vascular grafts.

A prime factor in the thrombogenicity of synthetic materials in contact with blood is the blood-gas interface. Small pockets of gas, known as gas nuclei, are trapped within surface interstices. The resulting blood-gas interface denatures plasma proteins and activates clotting factors and platelets. Expanded polytetrafluoroethylene (ePTFE) vascular prostheses 1 mm in internal diameter were placed in saline under 6,000 psig hydrostatic pressure for 2 h in an attempt to dissolve all gas nuclei (i.e., to denucleate). Carotid-carotid bypasses were performed in rats using 280-mm lengths of ePTFE. All 10 control grafts lost patency in 5 min, whereas the 14 denucleated grafts had a median patency duration of 300 min (P less than 0.01). In 15-mm-long rat femoral artery interpositional ePTFE grafts, 90% of controls thrombosed within 10 min, whereas only 7% of denucleated grafts thrombosed over the duration of the 7-day observation period (P less than 0.001). Denucleation also resulted in a significant reduction (P less than 0.02) in 111In-labeled platelet adhesion to 36% of control. Scanning electron microscopy confirmed the reduced accumulation of platelets on denucleated grafts. These data suggest that the removal of trapped air with hydrostatic pressure significantly reduces the thrombogenicity of ePTFE microvascular prostheses and may have application to other clinical (catheters, valves, tubing, etc.) or experimental (micropipettes, electrodes, etc.) materials that interface with blood.

Regional infusion of urokinase into occluded lower-extremity bypass grafts: long-term clinical results.

The initial outcome, long-term patency rate, and rate of limb salvage were studied in patients after regional urokinase infusion for treatment of thrombosed lower-extremity grafts. Seventy-one infusions were performed in 53 patients. Complete clot lysis occurred in 75% of grafts, with establishment of antegrade blood flow in 66%. Variables that favorably influenced clot lysis and the reestablishment of antegrade blood flow through the graft were a short duration of occlusion and a suprainguinal graft position. The median duration of patency after infusion and adjunctive therapy was 162 days, with 75% limb salvage at 301 days. No statistically significant variables that influenced the length of patency were identified. These long-term patency results are inferior to the reported results in suprainguinal grafts after reoperation. They appear similar to reported results for occluded infrainguinal grafts treated with thrombectomy and patch grafting.