Use Of Silicone Stents Research Articles

Evaluation and Comparison of the Outcomes of Endoscopic Dacryocystorhinostomy with and without Silicone Stent

Introduction Endoscopic dacryocystorhinostomy aims to establish a patent nasolacrimal fistula. Use of silicone stent is a preferred modification to achieve long term patency of neo-ostium, though it has been blamed for granulations, synechia and punctal erosion. Present study was done to evaluate and compare the outcomes of Endoscopic dacryocystorhinostomy with and without stent. Materials and Methods 40 patients of with chronic dacryocystitis and nasolacrimal duct blockage were selected for the study. Nasal endoscopy was done for suitability of surgical access and to detect any nasal pathology. Sac syringing was done to assess the site of blockage and Dacryoscintigraphy to confirm it. 20 patients in Group A underwent Endoscopic dacryocystorhinostomy without stent and remaining 20 in Group B with silicone stent. Success rates were determined by subjective relief from epiphora and by endoscopic visualization of rhinostomy opening, granulation tissues/ synechiae at rhinostomy site and by result of sac syringing. Results In Group A, complete relief was obtained in 75% patients, significant relief in 10% and no relief in 15% patients thus recording overall success rate of 85%; whereas in Group B complete relief of symptom was obtained in 70% patients, significant relief in 10% and no symptom relief in 20% patients thus recording the overall success rate of 80%. Cases in Group B were also found to have persistent epiphora (17.5%), stenosis of ostium (25%), granulation (35%) and synechia (37.5%). Conclusion Stenting does not significantly improve the success of Endoscopic dacryocystorhinostomy but is associated with more complications.

Is Stenting Really Necessary in Primary Endonasal DCR-Our Experience.

To Know the relevance of silicone intubation in Endoscopic DCR. A prospective randomized controlled trial study was conducted in the Department of ENT at Dr. Babasaheb Ambedkar Memorial Central Railway Hospital, Byculla, Mumbai. Duration of study was from March 2015 to November 2018. 100 patients in the age group ranging from 20 to 70years, with acquired Nasolacrimal duct obstruction with epiphora and recurrent dacryocystitis were evaluated and managed. These patients were randomized into two groups based on using table of random numbers into two Group A: DCR without stent (n = 50) and Group B: DCR with stent (n = 50). Every patient was subjected to detailed history and examination. The overall success rate in our study with silicone stent was 92% and without stent was 88%. There was no statistically significant (p > 0.05) difference between the two groups. According to our experience silicone stent is really not needed in Endoscopic DCR and if at all used it should be used up to 7days to prevent restenosis and to prevent mucosal flaps to cover stoma again. Use of silicone stent should be restricted to following cases like post traumatic, revision, fibrosed small contracted sac and suspected canalicular block cases.

Adjunctive techniques to dacryocystorhinostomy: an evidence-based review with recommendations.

Many adjunctive techniques exist for dacryocystorhinostomy (DCR), with varying levels of supportive evidence. Literature from PubMed, EMBASE, and Cochrane Databases was reviewed between January 1990 and January 2020 to examine evidence regarding the utility of adjunctive techniques to DCR, including mucosal flap preservation, concurrent septoplasty, stenting, topical mitomycin C (MMC), and 5-fluorouracil (5-FU), as well as perioperative antibiotics and steroids. Recommendations were made based on the evidence found. Seven adjunctive techniques used in DCR were examined. The literature supported concurrent septoplasty when septal deviation is present. Silicone stents are recommended for external DCR approaches. MMC use is optional in external DCR and revision cases. The literature does not support the routine use of silicone stents or MMC in primary endoscopic DCR. Mucosal flap preservation is optional, with evidence showing comparable results with or without utilization. The level of evidence is limited for topical 5-FU, as well as perioperative antibiotic and steroid use. Recommendations for adjunctive techniques to external and endoscopic DCR surgeries can be made based on the current literature. Higher-level studies are needed to better optimize perioperative approaches to DCR.

Assessment of Rhinostomy Parameters in Endonasal Dacryocystorhinostomy.

Epiphora is a bothersome condition seen in chronic dacryocystitis. The mainstay of treatment is surgical, that is creating an opening to establish a drainage pathway. With the advent of endoscope, endonasal DCR has gained popularity. Use of silicone stent in endonasal DCR has added advantage in improving the surgical outcome. And the use of DOS system in improving the success rates of endonasal DCR: (Mohammad et al. in Clin Ophthalmol 8:2491-2499, 2014) a total of 35 patients with chronic dacryocystitis were subjected for endonasal DCR with silicone bicanalicular stent. Patients were followed up at an interval of 1week, 3weeks, 6weeks and 6months post surgery. DCR ostium parameters were evaluated using DOS system. Silicone stent removal was done at sixth week and evaluated for success. The success rate in our study was 89%. The DOS score of the patient with successful surgery had a score of more than 30 and in the failed cases the score was between 22 and 28. The success rate of the procedure primarily depends on the ostium parameters and the position of the silicone stent. The DOS scoring system can be suitable tool in evaluating the same.

Role of silicone stenting in endoscopic dacryocystorhinostomy

<p class="abstract"><strong>Background:</strong> Dacryocystorhinostomy (DCR) is a surgical procedure performed to relief nasolacrimal duct obstruction, which involves the creation of ostium at the lacrimal bone to form a shunt in the nasolacrimal pathway. Closure of the rhinostomy opening was considered a major factor for surgical failure. Use of silicone stent in endoscopic DCR to improve the success rate of the operation have been tried by many surgeons. In this study we assess the success rates of endoscopic DCR with and without silicone stents.</p><p class="abstract"><strong>Methods:</strong> Prospective study includes 30 patients were operated in the Department of ENT, Misrata Medical Center, from April 2017 to March 2018. They underwent endonasal endoscopic DCR for primary acquired nasolacrimal duct obstruction.<strong> </strong>These patients were randomly divided in two groups: A and B with 15 patients in each group. The group A patients underwent endoscopic DCR with silicone stent and group B patients underwent endoscopic DCR without stent. The results were statistically analyzed by chi-square test. </p><p class="abstract"><strong>Results:</strong> 30 patients were included in this study, their age ranged from 17 to 60 years, complaining of epiphora, 24 (80%) were females and 6 (20%) were males. The success rate was higher in patients with silicone stent (93.33%) as compared to patients without silicone stent (86.67%) but this difference in the results is not statistically significant (As p value is 0.542 which is >0.05).</p><p><strong>Conclusions:</strong> Endoscopic DCR is safe, successful procedure for treatment of nasolacrimal duct obstruction and there was no significant difference in the success rates of performing endonasal DCR with silicone or without silicone stents.</p>

A comparative study of the results of endoscopic dacryocystorhinostomy with and without stent placement

Background: Nasolacrimal duct (NLD) obstruction is a common clinical entity encountered both by ophthalmologists as well as otorhinolaryngologists. Endoscopic dacryocystorhinostomy (DCR) has emerged as a gold standard surgery for treatment of this disorder. Silicone stents are often promoted as agents to maintain patency of surgically created fistula during postoperative period in this surgery. Aim: The aim of this study is to evaluate and compare the outcomes of endoscopic DCR with and without silicone stenting. Materials and Methods: A prospective observational study was conducted. Totally 50 patients with acquired NLD obstruction were enrolled in the study and were randomly assigned to two groups: Group I underwent the surgery with silicone stent placement while the Group II underwent the surgery without stent placement. The patients were evaluated in terms of relief of symptoms and postoperative complications. Results: The overall success rate for endoscopic DCR in this study was 90% which is comparable with the reports in the literature. Success rate for patients with placement of stent was 92% and without stenting was 88%. However, there was no significant statistical difference between the two groups. Conclusion: Use of silicone stents does not influence results of Endoscopic DCR.

Endonasal dacryocystorhinostomy without stents: our experience

<p class="abstract"><strong>Background:</strong> <span lang="EN-IN">Dacryocystorhinostomy (DCR) for the treatment of nasolacrimal duct obstruction. The aims of the study were to assess the patency rate of endoscopic (ED DCR) using a technique similar to that described by McDonogh and Meiring but without the use of nasolacrimal silicone stents. </span></p><p class="abstract"><strong>Methods:</strong> <span lang="EN-IN">Endonasal dacryocysto-rhinostomies (ED DCRs) were performed without the use of silicone stents in 46 patients (20 male, 26 female). These patients were followed up for an average of eight months. </span></p><p class="abstract"><strong>Results:</strong> <span lang="EN-IN">The procedure was successful in 86.95% of cases as measured by patient’s relief of symptoms and endoscopic visualization of a middle meatal ostium draining the lacrimal sac. </span></p><p class="abstract"><strong>Conclusions:</strong> <span lang="EN-IN">In our study ED DCR without stents had less complications and also a success rate of 86.95% achieved when compared with DCR with stents.</span></p>

Die Behandlung von Tränenwegsstenosen aus HNO‑ärztlicher Sicht

Epiphora is the classic symptom of nasolacrimal duct obstruction, particularly among elderly people. Dacryocystorhinostomy (DCR) via external (Toti) and endonasal (West) approaches are well-established surgical treatments. The aim of the present article is to describe the etiology and diagnostics of nasolacrimal duct obstruction. Furthermore, treatment modalities are discussed according to the current literature, with particular consideration of the otorhinolaryngologist's perspective. A search of the current literature focused on the past 5years was performed in PubMed. Several retrospective and prospective randomized studies describe the external and endonasal DCR approaches as safe surgical procedures, with high success rates of around 90 %. The endoscope is standardly used for visualization during the endonasal approach. Powered instruments such as diamond drills enable generation of alarge rhinostomy, even in very hard bone. The application of silicone stents does not confer a significant additional advantage in terms of postoperative success rates. DCR is asafe surgical procedure with high success rates. It can be strongly recommended for patients suffering from intra- or post-saccular nasolacrimal duct obstruction. Furthermore, the external and endonasal approaches (according to Toti and West, respectively) are comparable techniques. The use of silicone stents is indicated only in special cases.

The Learning Curve in Endoscopic Dacryocystorhinostomy: Outcomes in Surgery Performed by Trainee Oculoplastic Surgeons

Purpose: To report outcomes of endoscopic DCR (En-DCR) performed by oculoplastic trainees and describe factors to improve success rates for trainees.Methods: Retrospective, single-centre audit of En-DCR procedures performed by three consecutive trainee oculoplastic surgeons, over a 3-year period. Trainees also completed a reflective-learning questionnaire highlighting challenging and technically difficult aspects of En-DCR surgery, with relevant tips.Results: Thirty-eight consecutive independently-performed en-DCR procedures on 38 patients (mean age 58.6 ± 21.4 years) were studied. Mean time spent in the operating-theatre was 95.7 ± 27.3 minutes. Success rate for each year was 15/17(88%), 8/8(100%) and 7/13(54%), respectively, at mean follow-up 12.5 ± 12 months. The lowest success rate year coincided with use of silicone stents in 31% cases compared to 94% and 100% in the previous 2 years. In cases that failed, video-analysis highlighted inadequate superior bony rhinostomy (2 cases), incomplete retroplacement of posterior-nasal mucosal-flaps (3 cases), significant bleeding (1 case). Those who underwent revision surgery (n = 6), were found to have soft-tissue ostium and sac closure requiring flap revision. Two-cases required further bone removal supero-posterior to the lacrimal sac. Trainees-tips that helped improve their surgery related to patient positioning, instrument handling, bone removal and posture.Conclusion: Good surgical outcomes are achievable training in en-DCR surgery. Adequate operating time needs to be planned. Failure was primarily due to closure of the soft-tissue ostium, either secondary to inadequate osteotomy and sac-marsupialisation or postoperative scarring. Intra-operative mucosal trauma is higher amongst trainees and adjuvant silicone stenting during the training period may be of value where mucosal adhesions are anticipated.

Long-term functional reconstruction of segmental tracheal defect by pedicled tissue-engineered trachea in rabbits

Due to lack of satisfactory tracheal substitutes, reconstruction of long segmental tracheal defects (>6 cm) is always a major challenge in trachea surgery. Tissue-engineered trachea (TET) provides a promising approach to address this challenge, but no breakthrough has been achieved yet in repairing segmental tracheal defect. The longest survival time only reached 60 days. The leading reasons for the failure of segmental tracheal defect reconstruction were mainly related to airway stenosis (caused by the overgrowth of granulation tissue), airway collapse (caused by cartilage softening) and mucous impaction (mainly caused by lack of epithelium). To address these problems, the current study proposed an improved strategy, which involved in vitro pre-culture, in vivo maturation, and pre-vascularization of TET grafts as well as the use of silicone stent. The results demonstrated that the two-step strategy of in vitro pre-culture plus in vivo implantation could successfully regenerate tubular cartilage with a mechanical strength similar to native trachea in immunocompetent animals. The use of silicone stents effectively depressed granulation overgrowth, prevented airway stenosis, and thus dramatically enhanced the survival rate at the early stage post-operation. Most importantly, through intramuscular implantation and transplantation with pedicled muscular flap, the TET grafts established stable blood supply, which guaranteed maintenance of tubular cartilage structure and function, accelerated epithelialization of TET grafts, and thus realized long-term functional reconstruction of segmental tracheal defects. The integration of all these improved strategies finally realized long-term survival of animals: 60% of rabbits survived over 6 months. The current improved strategy provided a promising approach for long-term functional reconstruction of long segmental tracheal defect.

Temporary Use of Silicone Stents for Severe Airway Stenosis in Untreated Malignant Lymphoma

Airway stenting has become a popular method for palliation of airway stenosis; however, little has been reported about their use for patients with malignant lymphoma that occasionally causes a life-threatening condition. The aim of the study was to evaluate the efficacy and safety of airway stenting in chemoradiotherapy naive patients with severe airway stenosis due to malignant lymphoma. Patients who underwent airway stent placement from April 2007 to July 2011 in a single center were retrospectively reviewed. All stenting procedures were performed using rigid and flexible bronchoscopes under general anesthesia. We performed 174 airway stenting procedures (silicone stents in 154 procedures and metallic in 20 procedures) for 150 patients during the study period. Of the patients, 7 had untreated malignant lymphomas (4 diffuse large B-cell lymphomas, 2 lymphoblastic lymphomas, 1 mucosa-associated lymphoid tissue lymphoma). All patients underwent stenting using the silicone Y-stent (6 on the main carina and 1 on the primary right carina). Dyspnea was relieved immediately in 6 of 7 patients including the mechanically ventilated patient. Stents could be removed in all patients (median 90 d after stenting; range, 32 to 245 d) because of the tumor response to tumor-specific therapy. One granuloma formation and 1 mucus retention triggered the decision to remove the stents. Airway stenting using silicone stents is safe and effective in palliation of airway stenosis in patients with untreated malignant lymphoma, and permits postprocedural tumor-specific therapy. The response to tumor-specific therapy can be expected, and so removable stents should be selected.

Primary Endoscopic Dacryocystorhinostomy with or without Silicone Tubing: A Prospective Randomized Study

Endoscopic dacryocystorhinostomy (DCR) is an effective surgical procedure to treat saccal and postsaccal stenosis or nasolacrimal duct obstruction. The use of silicone tube after endoscopic DCR is still controversial. A prospective randomized study was conducted to compare the success rate between the use of silicone stent and no use of silicone stent in endoscopic DCR. A prospective randomized study was conducted at Aseer Central Hospital and Abha Private Hospital, Abha, Kingdom of Saudi Arabia, on all patients undergoing endoscopic DCR between July 1, 2006 and 30 June 30, 2010. Patients were allocated randomly for endoscopic DCR with or without stent. The data collection included age, sex, diagnosis, method, and duration of surgery. Patients were followed up postoperatively at 1 week, 1 month, and then every 3 months for 1 year. During the period of the study a total of 173 cases of postsaccal stenosis underwent endoscopic DCR (67 male and 106 female subjects). The mean age was 51.8 years (range, 18-72 years). A stent was used in 92 patients (53.2%) and not used in 81 patients (46.8%). With silicone tubing the success rate was 96%, and without silicone tubing it was 91%, an overall success rate of 94%. The odds ratio of failure without a silicone tube was 3.25 but confidence interval was from 0.84 to 12.60 and the difference between these two groups was statistically not significant (p = 0.117). In this study, there was no statistically significant advantage of using endoscopic DCR with stent over the endoscopic DCR without stent.

Reply to Dutau et al.

We thank Dr Dutau et al. [1] for their comments regarding our article ‘Novel biodegradable stents in the treatment of bronchial stenosis after lung transplantation’ [2]. In our previous experience, there was a place for both metal and silastic stents in tracheal and bronchial stenosis management, as the authors suggest. Silicone stents were used at our institution in the era before biodegradable stenting. Between January 1997 and January 2005, we performed 98 lung transplants in 67 patients (36 single-lung transplants and 31 bilateral-lung transplants). Four bronchial anastomotic complications requiring stenting (4.1%) occurred in four patients (6.0%). All were successfully treated with silicone–Dumon stents, which were removed at the end of the treatment. Due to our close cooperation with general surgeons, we were confronted with excellent results of biodegradable oesophageal stenting. After the appreciation of laboratory and ongoing animal studies [3], we decided to switch from silicone stents to biodegradable stents. We strongly believe that controlled biodegradation of stents is the future of any stenting, not only in airways. As our study was the very pilot study, we were limited in resources, patient population and of course experience. Currently, more biodegradable stents are available and the period of time for which the stents keeps its sufficient resistive radial forces could be chosen. We do not know if a multiple stent placement for a short period of time is superior to the single stent placement for a longer period of time with all concomitant risks (necrosis, granulation, displacement and complicated removal). This is an issue, which should be addressed in a multicentre trial, which is indeed inevitably needed. Currently, at our institution, we cannot justify the use of silicone stents in benign airway stenosis. Hence, we do not plan to conduct a prospective comparative study. Nevertheless, we feel that more evaluation is needed in designing, manufacturing and in vitro testing of polydioxanone biodegradable stents. Meanwhile, the use of these stents (currently not European Conformity marked) remains highly specifically indicated, although the recent results show high safety, efficacy and biocompatibility. First reports of biodegradable stenting in children (another challenging population with growing airways) were published by our colleagues from Great Ormond Street Hospital in London [4] and one prospective study is conducted in Hannover. To summarize, Dutau et al. are kind in their comments on the place of our work in the development of this field. We agree that future phase III trials of absorbable, and other new stents such as drug-eluting devices, should be compared with both metal and silastic stents, the gold standard comparator carefully chosen depending on the clinical setting. International collaboration in the design and conduct of these trials is essential, and for this reason, we fully welcome this debate and interest.

A retrospective study of silicone stent placement for management of anastomotic airway complications in lung transplant recipients: Short- and long-term outcomes

Airway anastomotic complications remain a major cause of morbidity and mortality after lung transplantation (LT). Few data are available with regard to the use of silicone stents for these airway disorders. The aim of this retrospective study was to evaluate the clinical efficacy and safety of silicone stents for such an indication. Data of adult lung transplant recipients who had procedures performed between January 1997 and December 2007 at our institution were reviewed retrospectively. We included patients with post-transplant airway complications who required bronchoscopic intervention with a silicone stent. In 17 of 117 (14.5%) LT recipients, silicone stents were inserted at a mean time of 165 (range 5 to 360) days after surgery in order to palliate 23 anastomotic airway stenoses. Symptomatic improvement was noted in all patients, and mean forced expiratory volume in 1 second (FEV(1)) increased by 672 +/- 496 ml (p < 0.001) after stent insertion. The stent-related complication rate was 0.13/patient per month. The latter consisted of obstructive granulomas (n = 10), mucus plugging (n = 7) and migration (n = 7), which were of mild to moderate severity and were successfully managed endoscopically. Mean stent duration was 266 days (range 24 to 1,407 days). Successful stent removal was achieved in 16 of 23 cases (69.5%) without recurrence of stenosis. Overall survival was similar in patients with and without airway complications (p = 0.36). Silicone stents allow clinical and lung function improvement in patients with LT-related airway complications. Stent-related complications were of mild to moderate severity, and were appropriately managed endoscopically. Permanent resolution of airway stenosis was obtained in most patients, allowing definitive stent removal without recurrence.

A Systematic Review of Outcomes after Dacryocystorhinostomy in Adults

This study was designed to systematically review the clinical outcomes of dacryocystorhinostomy (DCR) surgery. Data sources included PubMed for English language literature from January 1966 to December 2008 combined with a manual review of citations within article bibliographies. Citations acquired from the targeted search were filtered independently by two researchers. Relevant articles were reviewed to obtain information including interventions and outcome measures. The surgical techniques were categorized into external DCR (EX-DCR), endonasal laser-assisted DCR (LA-DCR), and nonlaser endoscopic endonasal DCR techniques (EN-DCR). Articles were then assigned level-of-evidence grades as defined by the Oxford Center for Evidence-Based Medicine. A total of 73 studies that fulfilled the inclusion criteria were analyzed. Of these, 68 were graded as level 4, 11 were graded as level 3b, and 1 was graded at level 2b evidence. A total of 4800 patients were pooled, from which 4921 DCRs were performed. All studies reported success during the follow-up period, although the outcome measures used were not consistent in the studies. Success varied between 65 and 100% after EX-DCR compared with EN-DCR, which varied from 84 to 94%. The success rate of LA-DCR varied widely between 47 and 100%. There was low evidence base to support the use of silicone stent to improve surgical success. Most studies did not show significantly improved outcomes with an antimetabolite. The overall intra- and postoperative complication rates were 1.0 and 6%, respectively. DCR is an effective and safe method for the treatment of nasolacrimal obstruction. Meta-analysis of outcomes was not feasible because of the heterogenous patient groups and outcome measures used. Nonetheless, the literature provides considerable levels 3 and 4 evidence to support DCR surgery in adults. Outcomes after EN-DCR and EX-DCR were comparable. The failure rate for LA-DCR was higher.

Use of silicone stents for the management of post-tuberculosis tracheobronchial stenosis

The role of bronchoscopic management in post-tuberculosis tracheobronchial stenosis is not well defined. To investigate the role of bronchoscopic intervention, including silicone stenting, in the management of post-tuberculosis tracheobronchial stenosis, the current retrospective study was conducted at a tertiary referral hospital. Under rigid bronchoscopy, 80 patients underwent ballooning, neodymium-yttrium aluminium garnet laser resection and/or bougienation as first-line methods of airway dilatation between January 2000 and December 2003 inclusive, and were followed for a median of 41 months. Silicone stents were required in 75 out of 80 (94%) patients to maintain airway patency. Bronchoscopic intervention provided immediate symptomatic relief and improved lung function in 88% of the patients. After airway stabilisation, stents were removed successfully in 49 out of 75 (65%) patients at a median of 14 months post-insertion. Three patients out of 75 (4%) eventually underwent surgical management. Acute complications included: excessive bleeding (n = 1); pneumothorax (n = 5); and pneumomediastinum without mortality (n = 2). Stent-related late complications, such as migration (51%), granuloma formation (49%), mucostasis (19%) and re-stenosis (40%), were controllable during a median follow-up of 41 months. In conclusion, bronchoscopic intervention, including silicone stenting, could be a useful and safe method for treating post-tuberculosis tracheobronchial stenosis.

Novel management of a large chronic bronchocutaneous fistula after lobectomy

We describe the successful use of silicone stent for the treatment of chronic bronchocutaneous fistula in a patient with a large stump opening of 20 mm in diameter. A literature review of bronchoscopic treatment of bronchopleural fistula (BPF) is also discussed here.

Prevention of Prolapsed Silicone Stents in Lacrimal Intubation Using an Intrasac Fixation Suture

Silicone stents are routinely used for the maintenance of patent mucosal passages in patients with nasolacrimal disorders. A common complication associated with the use of silicone stents is lateral migration or displacement of the tubes, which can be difficult to correct. This report describes a modified Quickert-Dryden approach with fixation of the tubes by an intrasac suture. From 1990 to 1996, 53 patients had silicone stents placed by this method with no complications related to tube displacement. The intrasac fixation suture has distinct advantages over other fixation methods.

Use of Silicone Stents in the Management of Subglottic Stenosis

Use of Silicone Stents in the Management of Subglottic Stenosis

Antegrade double J ureteral stenting for ureteric strictures: use of silicone stents.

In 16 patients with ureteric strictures, silicone double J ureteral stents were inserted antegradely following percutaneous nephrostomy. In 9 patients prior attempt at retrograde placement of a stent had failed. Balloon dilatation of the stricture using angiographic catheters was also performed in 5 patients. The ureteric strictures were most commonly caused by malignant infiltration, post operative fibrosis, infection and ureteric calculi. Most previous reports have described the use of polyethylene and polyurethrane stents. Technical problems with the use of silicone stents are discussed. Although silicone stents are better tolerated by patients and associated with low complication rates, in 5 of 18 stents inserted (28%) the procedure failed. Suboptimal positioning of the stent due to poor radio-opacity and premature occlusion were the causes. With the availability of co-polymer stents, it is likely that these will replace silicone stents as the stent material of choice for antegrade insertion.