Comparison of covered and uncovered self-expandable stents in the treatment of malignant biliary obstruction

Background and objective: Drainage with metallic stents is the treatment of choice in malignant obstructive jaundice. Technical and clinical success with metallic stents is obtained in over 90% and 80% of cases, respectively. There are self-expandable metallic stents designed to increase permeability. The aim of this study was to describe the results obtained with totally covered self-expandable and uncovered self-expandable metallic stents in the palliative treatment of malignant biliary obstruction. Patients and methods: Sixty eight patients with malignant obstructive jaundice secondary to pancreatobiliary or metastatic disease not amenable to surgery were retrospectively included. Two groups were created: group A (covered self-expandable metallic stents) (n = 22) and group B (uncovered self-expandable metallic stents) (n = 46). Results: Serum total bilirubin, direct bilirubin, alkaline phosphatase and gamma glutamyl transferase levels decreased in both groups and no statistically significant difference was detected (p = 0.800, p = 0.190, p = 0.743, p = 0.521). Migration was greater with covered stents but it was not statistically significant either (p = 0.101). Obstruction was greater in the group with uncovered stents but it was not statistically significant either (p = 0.476). Conclusion: There are no differences when using covered self-expandable stents or uncovered self-expandable stents in terms of technical and clinical success or complications in the palliative treatment of malignant obstructive jaundice.

Oversizing and Restenosis with Self-Expanding Stents in Iliofemoral Arteries

Uncoated self-expanding nitinol stents (NS) are commonly oversized in peripheral arteries. In current practice, 1-mm oversizing is recommended. Yet, oversizing of NS may be associated with increased restenosis. To provide further evidence, NS were implanted in porcine iliofemoral arteries with a stent-to-artery-ratio between 1.0 and 2.3. Besides conventional uncoated NS, a novel self-expanding NS with an antiproliferative titanium-nitride-oxide (TiNOX) coating was tested for safety and efficacy.

Use of nitinol self-expandable stents in 26 dogs with tracheal collapse

A study was designed to describe a novel approach to the treatment of tracheal collapse (TC) in dogs using self-expandable nitinol stents. Medical records were reviewed retrospectively for 26 client owned dogs in which nitinol stents were deployed. The entire length of trachea was supported independently of the extent of TC. Two overlapping stents were used instead of one in cases where one stent was not spanning the entire trachea adequately. The diameter of the cranial radiolucent portion of trachea, just behind the cricoid cartilage, was measured as a specific landmark to select the appropriate size of the stent. Two self-expandable nitinol stents were inserted in 9 of 26 dogs; the trachea in the rest of the cases was supported with only one stent. A follow up tracheoscopy was performed in 10 of 26 cases with recurrent clinical signs. Secondary tracheal stenosis in these cases was caused by stent fracture, granuloma or excessive stent shortening. Additional stents were placed successfully to expand the stenotic lumen. A support of the entire trachea may decrease risk of nitinol fracture at the end of the implant. Long term clinical improvement (25 of 26 dogs, 96 %) is comparable with the results of other studies.

Simulation of a mechanical thrombectomy device based in the use of self-expandable stents for the blood clots extraction

Recently, we have presented some studies concerning the analysis, design and optimization of one experimental device developed in the UK - GPTAD - which has been designed to remove blood clots without the need to make contact with the clot itself, thereby potentially reducing the risk of problems such as downstream embolisation. Based on the idea of a modification of the previous device, in this work, we present a model based in the use of stents like the SolitaireTM FR, which is in contact with the clot itself. In the case of such devices, the stent is self-expandable and the extraction of the blood clot is faciliatated by the stent, which must be inside the clot. Such stents are generally inserted in position by using the guidewire inserted into the catheter. This type of modeling could potentially be useful in showing how the blood clot is moved by the various different forces involved. The modelling has been undertaken by analyzing the resistances, compliances and inertances effects. We model an artery and blood clot for range of forces for the guidewire. In each case we determine the interaction between blood clot, stent and artery.

Future trials of endovascular mechanical recanalisation therapy in acute ischemic stroke patients: a position paper endorsed by ESMINT and ESNR : Part I: Current situation and major research questions

A new era of stroke treatment may have begun with mechanical thrombectomy (MT) by fully deployed closed-cell self-expanding stents (stent-triever). Multiple case series and the first randomised controlled trials (RCTs) have now been published. More studies are under way involving large numbers of patients, which in turn has resulted in less strict "pragmatic" study protocols. Problems with current trials include a lack of standardisation in the conduct of the recanalisation procedure, the definition of primary endpoints such as the grade of arterial recanalisation and tissue reperfusion, and the post-surgical care provided. In Part 1 of this two part series, we outline the current situation and the major research questions.

Influence of stent type on hemodynamic depression after carotid artery stent placement

PURPOSE: To assess the effect of stent type on hypotension and bradycardia after carotid artery stent placement. MATERIALS AND METHODS: A retrospective analysis on a prospectively maintained database was conducted in 256 patients (126 men; mean age, 71.8 years +/- 8.6; 194 de novo lesions) undergoing carotid artery stent placement between January 1996 and January 2007 by using self-expanding stents. Braided Elgiloy stents (Wallstents) were used in 44 of the 256 patients (17.2%) and slotted-tube nitinol stents were deployed in 212 (82.8%). Bivariate and multivariable logistic regression models were used to determine the influence of stent design on procedural and 24-hour hypotension and bradycardia. RESULTS: Procedural hemodynamic depression (HD) was encountered in 73 of the 256 patients (28.5%) due to hypotension in 24 (9.4%), bradycardia in 12 (4.7%), or both in 37 (14.5%) patients. Rates of procedural hypotension were 11.3% with nitinol stents and 0% with braided Elgiloy stents (P = .0188). Persistent postprocedural HD occurred in 91 of the 256 patients (35.5%) due to hypotension in 40 patients (15.6%), bradycardia in 23 (9.0%), or both in 28 (10.9%). Within a multivariable analysis adjusted for clinically relevant factors affecting rates of HD, the use of braided Elgiloy stents was associated with a decreased rate of procedural hypotension (odds ratio: 0.165; 95% confidence interval: 0.038, 0.721; P = .017). Procedural hypotension and bradycardia were not correlated to incidence of major adverse events but were associated with an increased duration of hospital stay (P = .0059 and P = .0335, respectively). CONCLUSIONS: Nitinol stents are associated with a higher risk of hypotension as compared to braided Elgiloy stents during carotid artery stent placement.

Self-expanding metal stents in postoperative esophageal leaks

Background: Postoperative esophageal leaks have a high morbidity and mortality. Self-expanding metal stents (SEMS) have been used as an alternative to re-operation. Aim: Evaluating predictors of success of SEMS in postoperative esophageal leaks. Methods: Retrospective study of patients with postoperative esophageal leaks referred for SEMS placement in a reference center during a period of 3 years. Technical success was defined as closure of the leak in barium swallow at 15 days. Clinical success was considered as endoscopic and/or radiographic confirmation of closure after stent removal. Results: Thirteen patients placed SEMS. Median follow-up was 58 days. Leaks had a median size of 20 mm. Time between surgery and SEMS placement was 20 days. One patient died 2 days after SEMS placement and one had worsening of the fistula after SEMS expansion. Time till stent migration was 9 days. Technical success was achieved in 9 of 11 patients, with clinical success without recurrence in 5 patients. All leaks with less than 20 mm were solved endoscopically. Technical and clinical success was higher when time between surgery and SEMS placement was lower, even though without statistical significance (respectively, p = 0.228 and 0.374). In the 8 patients who died during follow-up, median survival was 59 days. Conclusions: Technical success of SEMS was higher than 80%; however, due to high morbidity and mortality, only 45% of patients had their stent removed. Lower time from diagnosis to SEMS placement and leak size less than 20 mm may be associated with better results.

Stimuli-responsive weak polyelectrolyte multilayer films: A thin film platform for self triggered multi-drug delivery

Polyelectrolyte multilayer (PEM) thin film composed of weak polyelectrolytes was designed by layer-by-layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) for multi-drug delivery applications. Environmental stimuli such as pH and ionic strength showed significant influence in changing the film morphology from pore-free smooth structure to porous structure and favored triggered release of loaded molecules. The film was successfully loaded with bovine serum albumin (BSA) and ciprofloxacin hydrochloride (CH) by modulating the porous polymeric network of the film. Release studies showed that the amount of release could be easily controlled by changing the environmental conditions such as pH and ionic strength. Sustained release of loaded molecules was observed up to 8 h. The fabricated films were found to be biocompatible with epithelial cells during in-vitro cell culture studies. PEM film reported here not only has the potential to be used as self-responding thin film platform for transdermal drug delivery, but also has the potential for further development in antimicrobial or anti-inflammatory coatings on implants and drug-releasing coatings for stents. (C) 2015 Elsevier B.V. All rights reserved.

Treatment of malignant gastroduodenal obstruction with a nitinol self-expanding metal stent: An international prospective multicentre registry

Background: Duodenal stenting has become a broadly accepted first line of treatment for patients with advanced malignant gastroduodenal obstruction as these patients are difficult to treat and are poor surgical candidates. Aims: To document duodenal stent performance for palliative management of malignant gastroduodenal obstruction. Methods: Multicentre, single arm, prospective registry documenting peroral endoscopic duodenal stenting procedures in 202 patients. Results: Technical success achieved in 98% (CI. 95%, 99%) of stent placements. Increase of Gastric Outlet Obstruction Score by at least 1 point compared to baseline was achieved in 91% (CI, 86%, 95%) of patients persisting for a median of 184 days (CI, 109, 266). By day 5 (CI, 4,6) after stent placement, 50% of patients experienced a score increase of at least 1 point. Improvement from 14% of patients at baseline tolerating soft solids or low residue/normal diet to 84% at 15 days, 86% at 30 days, 81% at 90 days, 79% at 180 days, and 70% at 270 days. Complications included stent ingrowth and/or overgrowth (12.4%), transient periprocedural symptoms (3%), bleeding (3%), stent migration (1.5%), and perforation (0.5%). Conclusions: Safety and effectiveness of duodenal stenting for palliation of malignant gastroduodenal obstruction was confirmed in the largest international prospective series to date. (C) 2011 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Stent placement in acute cerebral artery occlusion: use of a self-expandable intracranial stent for acute stroke treatment

Stent placement has been applied in small case series as a rescue therapy in combination with different thrombolytic agents, percutaneous balloon angioplasty (PTA), and mechanical thromboembolectomy (MT) in acute stroke treatment. These studies report a considerable mortality and a high rate of intracranial hemorrhages when balloon-mounted stents were used. This study was performed to evaluate feasibility, efficacy, and safety of intracranial artery recanalization for acute ischemic stroke using a self-expandable stent.

Incidence and clinical implications of stent fractures of the Xpert self-expanding nitinol stent in infrainguinal arteries

BACKGROUND: Different stents in infrainguinal arteries have recently been associated with stent fractures and unfavorable clinical outcome, although data is limited regarding fractures of the Xpert selfexpanding nitinol stent. Thus, purpose of the present investigation was to evaluate its incidence and clinical implications in lower limb arteries. PATIENTS AND METHODS: Fifty-three consecutive patients (53 limbs) with peripheral arterial disease underwent secondary Xpert stent implantation due to suboptimal primary balloon angioplasty (PTA). Median age was 76 years. Stent fractures were evaluated by plain X-ray at median follow-up of 16 months. Stent patency was assessed by duplex ultrasound and sustained clinical improvement was defined as improvement of the ABI of > or = 0.10 together with improvement of at least one Rutherford class above the baseline finding throughout follow-up. RESULTS: Median length of femoropopliteal and infrapopliteal lesion was 3.0 and 2.3 cm, respectively. Sixtyfive stents were implanted in 43 limbs with femoropopliteal and 10 stents in 10 limbs with infrapopliteal lesion, respectively. Stent fractures occurred in 3 of 43 limbs (7.0%) of patients with femoropopliteal lesion with stent-based fracture rate of 4.6%. All fractured stents showed multiple struts fractures and occurred in the distal and middle superficial femoral artery. No stent fracture was observed in infrapopliteal lesions. The fractured stents were not associated with any clinical deterioration. Sustained clinical improvement was 71.0% and 54.6% for femoropopliteal and infrapopliteal lesions, respectively. Stent patency assessed by duplex was 65.2 and 63.9% for femoropopliteal and infrapopliteal lesions, respectively. CONCLUSIONS: Fractures of the Xpert stent were seldom and not associated with unfavorable clinical outcome at midterm follow-up.

Toward Self-Organising Service Communities

This paper discusses a framework in which catalog service communities are built, linked for interaction, and constantly monitored and adapted over time. A catalog service community (represented as a peer node in a peer-to-peer network) in our system can be viewed as domain specific data integration mediators representing the domain knowledge and the registry information. The query routing among communities is performed to identify a set of data sources that are relevant to answering a given query. The system monitors the interactions between the communities to discover patterns that may lead to restructuring of the network (e.g., irrelevant peers removed, new relationships created, etc.).