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Stent migration is one of the common complications after tracheal stent implantation. The causes of stent migration include size mismatch between the stent and the trachea, physiological movement of the trachea, and so on. In order to solve the above problems, this study designed a non-uniform Poisson ratio tracheal stent by combining the size and structure of the trachea and the physiological movement of the trachea to improve the migration of the stent, meanwhile ensuring the support of the stent. In this study, the stent corresponding to cartilage was constructed with negative Poisson's ratio, and the stent corresponding to the circular connective tissue and muscular membrane was constructed with positive Poisson's ratio. And four kinds of non-uniform Poisson's ratio tracheal stents with different link lengths and negative Poisson's ratio were designed. Then, this paper numerically simulated the expansion and rebound process of the stent after implantation to observe the support of the stent, and further simulated the stretch movement of the trachea to calculate the diameter changes of the stent corresponding to different negative Poisson's ratio structures. The axial migration of the stent was recorded by applying different respiratory pressure to the wall of the tracheal wall to evaluate whether the stent has anti-migration effect. The research results show that the non-uniform Poisson ratio stent with connecting rod length of 3 mm has the largest diameter expansion in the negative Poisson ratio section when the trachea was stretched. Compared with the positive Poisson's ratio structure, the axial migration during vigorous breathing was reduced from 0.024 mm to 0.012 mm. The negative Poisson's ratio structure of the non-uniform Poisson's ratio stent designed in this study did not fail in the tracheal expansion effect. Compared with the traditional stent, the non-uniform Poisson's ratio tracheal stent has an anti-migration effect under the normal movement of the trachea while ensuring the support force of the stent.

Background and Objectives : Endoscopic biliary plastic stenting is a safe and effective temporary therapeutic modality used in various benign biliary disorders. Long-term indwelling stents for more than one year without retrieval are termed "forgotten biliary stents". In clinical practice, the forgotten stents are underestimated and the majority of data were obtained from case reports. The aim of this study was to determine the forgotten-biliary-plastic-stent-related complications, their management, and the patients' clinical outcomes. Materials and Methods : This retrospective study was performed at three hospitals during the period from January 2021 to December 2023. In total, 577 patients with biliary plastic stents-inserted for a variety of benign biliary conditions-were included. They were divided into two groups, as follows: group 1 included 527 patients who had biliary stents removed within 3 months, and group 2 included 50 patients with biliary stents retrieved after one year of their deployment. The stent-related complications (e.g., acute cholangitis, stent clogging, distal stent migration, new common bile duct (CBD) stone formation, and proximal stent migration) and the endoscopic management success rate were evaluated. Results : Irretrievable CBD stones were the main indication for biliary plastic stenting in both groups. The stent-related complications, number of endoscopic sessions, and hospital admissions were significantly higher in the patients with forgotten biliary stents than those with stent removal within 3 months. All the study patients were successfully managed endoscopically with uneventful outcomes. Conclusions : Based on this retrospective study, non-adherence to the endoscopists' instructions is the main reason for retained biliary stents for more than one year. The patients with forgotten stents had significantly higher complication rates, a higher number of endoscopic sessions, and a higher number of hospital admissions than those with stents that were retrieved in the scheduled time. All patients were managed endoscopically with a technical success rate of 100%, and with no complication-related mortality.

Purpose: To evaluate the efficacy and safety of a novel technique for removal of migrated esophageal stent (MES) under fluoroscopy., Methods: From January 2009 to April 2023, 793 patients with a dysphagia score of 3-4 underwent esophageal stenting at our center, and 25 patients (mean age: 70.06 years old; male/female: 15/10) underwent stent removal using "loop method" under fluoroscopy. The primary outcomes were technical success and complications. The secondary outcomes were procedure time, radiation exposure, biochemical indicators [white blood cell (WBC), hemoglobin (Hb), platelet (PLT), albumin (ALB), alanine transaminase (ALT), total bilirubin (TB), urea nitrogen (UN) and C-reactive protein] of pre- and post-treatment at 2 weeks., Results: Technical success was 100% without major complications. The mean procedure time was (39.44 ± 9.28) minutes, which showed no statistical significance between benign (n = 5) and malignant (n = 20) group [(42.40 ± 8.85) vs (38.71 ± 9.46) mins, p > 0.05]. The mean radiation exposure was (332.88 ± 261.47) mGy, which showed no statistical significance between benign and malignant group [(360.74 ± 231.43) vs (325.92 ± 273.54) mGy, p > 0.05]. Pre- and post-procedure Hb [(114.46 ± 11.96) vs. (117.57 ± 13.12) g/L] and ALB [(42.26 ± 3.39) vs. (44.12 ± 3.77) g/L] showed significant difference (p < 0.05), while WBC, PLT, CRP, and ALT showed no significance (p > 0.05)., Conclusion: Fluoroscopy-guided "Loop method" for MES removal is an effective and safe alternative technique., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Trans-cell approach for the Neuroform Atlas stent (Stryker Neurovascular, Fremont, CA) is occasionally unsuccessful as a microcatheter can become stuck in the struts. This study aimed to evaluate the passability and impassability of 0.0165-inch microcatheters through the Neuroform Atlas stent using a simplified benchtop model., Methods: The distal struts of the target cell, referred to as the concave or convex crown, were found to interfere with microcatheter advancement during the trans-cell approach. The procedure was performed across each crown using the 1.7-Fr SL-10 and 1.6-Fr Headway Duo microcatheters (MicroVention-Terumo, Aliso Viejo, CA), and it was repeated 20 times. We evaluated the procedural success rate, passability of each microcatheter using the maximum moving distance of the target crown in successful procedures, and device behaviors., Results: The procedural success rate across the concave crown was significantly higher than that across the convex crown in both microcatheters. The maximum moving distance of the concave crown was significantly shorter in the Headway Duo microcatheter than in the SL-10 microcatheter. All procedures across the convex crown were not successful because the sharp end of the crown fell into the interspace inside the microcatheter tip, which is referred to as the crown jackpot phenomenon. The trapped microcatheter was never released from the crown unless it was pulled back proximally., Conclusions: Target crowns and microcatheters affected the use of the trans-cell approach through the Neuroform Atlas stent. The passability was excellent in a lower profile 0.0165-inch microcatheter. Moreover, neurointerventionalists must be knowledgeable of the crown jackpot phenomenon, which might cause fatal stent migration., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To evaluate the impact of compliance with anatomical guidelines on outcomes of endovascular aortic aneurysm repair using "bell-bottom" stent grafts (BBSGs)., Methods: This is a retrospective review from January 1999 to May 2012 of patients who underwent endovascular infrarenal abdominal aneurysm repair and whose iliac limbs were greater than 18 mm in diameter. Computed tomography angiography was utilized for compliance with anatomical guidelines as stated in manufacturer's instructions for use (IFU). The primary outcome observed was iliac limb events. The secondary outcome observed was the need for re-intervention due to BBSG failure., Results: Of the 376 BBSGs, 55 (15%) in 27 patients met IFU. Aneurysm exclusion was achieved in all patients. The mean follow-up was 44 ± 30 months. Twenty-eight patients (11%) had 29 iliac limb events (12 type 1b endoleaks, 4 aneurysm sac growth, 4 stenosis/kink, 4 retrograde migrations, 2 component separations, 2 ruptures and 1 limb occlusion); all among patients treated outside of IFU (p < 0.04). The rate of aneurysm sac enlargement was similar between both groups, at 56%, respectively, between those treated within and those treated outside of IFU. On multivariate regression analysis, larger common iliac artery (CIA) (HR 1.088, 95% CI 1.016-1.166, p = 0.016), greater CIA tortuosity (HR 2.352, 95% CI 1.004-5.509, p = 0.048) and limbs with more than two characteristics that did not meet IFU criteria (HR 3.84, 95% CI 1.15-12.83, p = 0.03) were associated with higher rates of BBSG events and re-interventions., Conclusions: BBSGs effectively seal ectatic CIAs. But rates of iliac limb events and re-interventions are higher among patients who do not meet IFU criteria. The larger CIA diameter, the greater CIA tortuosity and more than two criteria not met by IFU were associated with BBSG failure and re-intervention.

Backgrounds: Fully covered self-expandable metal stent (FCSEMS) are preferred for distal malignant biliary stricture (MBS). However, stent migration is a major adverse event of FCSEMS, especially for far distal MBS. We evaluated the usefulness of newly modified FCSEMS (M-FCSEMS) having 12 mm in diameter and anti-migration feature to minimize stent migration compared with the conventional FCSEMS (C-FCSEMS)., Methods: Total 102 patients were enrolled between January 2015 and September 2017 in this prospective comparative study; 50 were allocated to the M-FCSEMS group and 52 to the C-FCSEMS group. The primary outcome was stent migration, and the secondary outcomes were other adverse events, stent occlusion rate, and stent patency during the follow-up period., Results: The baseline characteristics of the two groups did not significantly differ. Endoscopic stent placement was technically successful in all patients. Stent migration occurred in 8.0% (4/50) of the patients in the M-FCSEMS group and 23.1% (12/52) of those in the C-FCSEMS group (P = 0.036). The other adverse events, including stent-related pancreatitis and cholecystitis did not significantly differ between the two groups (P = 0.415). Stent occlusion occurred in 23.9% (11/46) of the patients in the M-FCSEMS group and 37.5% (15/40) in the C-FCSEMS group (P = 0.171). Stent patency was significantly longer in the M-FCSEMS group than in the C-FCSEMS group (228 vs 157 days, P = 0.048)., Conclusions: Modified FCSEMS with 12-mm diameter and anti-migration feature significantly decreased the risk of stent migration and had longer patency compared with C-FCSEMS in patients with periampullary MBS., (© 2019 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Background and Aim: Pancreatic plastic stents (PPS) can reduce the risk of post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP). Prospective multicenter documentation of PEP rate after PPS placement is scarce. A new 4-Fr stent designed to be deployed over a 0.035-inch guidewire was used to assess the effectiveness of PEP prophylaxis., Methods: High-PEP-risk patients received a 4-Fr PPS for primary or secondary prophylaxis at seven centers in four countries. Patients were followed until spontaneous PPS migration, endoscopic stent removal, or for 4 months, whichever came first. Main outcome was PEP rate., Results: One hundred six (106) patients received PPS for PEP prophylaxis [61 (58%) primary, 45 (42%) secondary prophylaxis]. Median age was 54 years. Eighty-one (76%) PPS were placed using a 0.035-inch guidewire. By investigator choice 99 (93%) stents were single pigtail. Median stent length was 8 cm (range 3-12 cm). Technical success achieved in 100% of cases. Two patients in the primary prophylaxis group (3%, 95% CI 0.4-11%) experienced mild/moderate PEP. Seventy-eight PPS available for analysis underwent spontaneous migration after a median of 29 days. There were no reports of stent-induced ductal trauma. Post-hoc analysis of migration rate by PPS length showed no statistically significant trend., Conclusions: Among high-risk patients in the primary prophylaxis group, observed rates of PEP are low (3%, 95% CI 0.4-11%) with the use of prophylactic 4-Fr pancreatic duct stents compatible with a 0.035-inch guidewire. This low rate is not unequivocally due to the prophylactic stent., (© 2018 Japan Gastroenterological Endoscopy Society.)

Objective: Endovascular aneurysm repair (EVAR) has become the standard of care for infrarenal aneurysms. Endografts are commercially available in proximal diameters up to 36 mm, allowing proximal seal in necks up to 32 mm. We sought to further investigate clinical outcomes after standard EVAR in patients requiring large main body devices., Methods: We performed a retrospective review of a prospectively maintained database for all patients undergoing elective EVAR for infrarenal abdominal aortic aneurysms at a single institution from 2000 to 2016. Only endografts with the option of a 34- to 36-mm proximal diameter were included. Requisite patient demographics, anatomic and device-related variables, and relevant clinical outcomes and imaging were reviewed. The primary outcome in this study was proximal fixation failure, which was a composite of type IA endoleak and stent graft migration >10 mm after EVAR. Outcomes were stratified by device diameter for the large-diameter device cohort (34-36 mm) and the normal-diameter device cohort (<34 mm)., Results: There were 500 patients treated with EVAR who met the inclusion criteria. A total of 108 (21.6%) patients received large-diameter devices. There was no difference between the large-diameter cohort and the normal-diameter cohort in terms of 30-day (0.9% vs 0.95%; P = .960) or 1-year mortality (9.0% vs 6.2%; P = .920). Proximal fixation failure occurred in 24 of 392 (6.1%) patients in the normal-diameter cohort and 26 of 108 (24%) patients in the large-diameter cohort (P < .001). There were 13 (3.3%) type IA endoleaks in the normal-diameter cohort and 16 (14.8%) in the large-diameter cohort (P < .001). Stent graft migration (>10 mm) occurred in 15 (3.8%) in the normal-diameter cohort and 16 (14.8%) in the large-diameter cohort (P < .001). After multivariate analysis, only the use of Talent (Medtronic, Minneapolis, Minn) endografts (odds ratio [OR], 4.50; 95% confidence interval [CI], 1.18-17.21) and neck diameter ≥29 mm (OR, 2.50; 95% CI, 1.12-5.08) remained significant independent risk factors for development of proximal fixation failure (OR, 3.99; 95% CI, 1.75-9.11)., Conclusions: Standard EVAR in patients with large infrarenal necks ≥29 mm requiring a 34- to 36-mm-diameter endograft is independently associated with an increased rate of proximal fixation failure. This group of patients should be considered for more proximal seal strategies with fenestrated or branched devices vs open repair. Also, this group likely needs more stringent radiographic follow-up., (Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Stent migration is a common complication in treating trachea stenosis. There is no report concerning suture fixation of tracheal stent. The aim of this study was to investigate whether suture fixation of tracheal stent could avoid stent migration in patients with upper trachea stenosis. The complications were further investigated., Methods: The patients with upper trachea stenosis who underwent tracheal stent placement for benign/malignant conditions in our hospital between May 2016 and April 2018 were retrospectively reviewed. Clinical data were collected for each patient, including age, gender, co-morbid diseases, site of tracheal obstruction, degree of tracheal obstruction, success of stent placement, impact on patient's symptoms, complications, etc. RESULTS: Eleven patients (8 males and 3 females; range of age: 17-85, and average age of 63) were enrolled into this study. Six silicone stents and five membrane-covered metal stents were used. The surgery was successfully performed in all the cases. The postoperative recovery was uneventful. All symptoms of the patients were relieved. No complications occurred. The average follow-up for patients was 5 months (range of 1-13 months). During the follow-up, no stent migration was observed according to CT and bronchoscope., Conclusion: The results suggested that suture fixation of stents could avoid stent migration in treating upper trachea stenosis with metal stent or silicone stent. This method seemed to be effective without operation complications.

A neonatal ductal stent deployed in a straight short conical duct on second postnatal day migrated owing to inadequate ductal constriction. It was successfully retrieved using a larger balloon and redeployed in the duct again. Intravenous indomethacin prevented further stent migration. This is the first report of successful transcatheter retrieval and repositioning of a migrated expanded neonatal ductal stent.

Purpose: Although EUS-guided hepaticogastrostomy (EUS-HGS) with a covered self-expandable metal stent (SEMS) is a useful procedure, it is associated with severe adverse events, including stent migration. We, therefore, developed an intra-conduit release method, and investigated whether the technique yields a safer and more stable procedure., Methods: The intra-conduit release method is a procedure to release the SEMS in the working channel conduit of the scope for anchoring between the liver and stomach to avoid stent migration. Forty-three patients who underwent EUS-HGS at two high-volume centers in Japan were enrolled in this retrospective study, and the safety and usefulness of this method were evaluated retrospectively., Results: The intra-conduit release method was applied in 36 cases. The technical success rate of EUS-HGS with the intra-conduit release method was significantly higher in comparison with the conventional method. Additionally, the rate of early adverse events was significantly lower than that for the conventional method., Conclusion: The intra-conduit release method during EUS-HGS is useful for a stable procedure that avoids early adverse events.

Backgrounds: Stent migration following endoscopic ultrasonography-guided hepaticogastrostomy (EUS-HGS) may sometimes be fatal because there are no adhesions between the biliary tract and stomach. To prevent stent migration and minimize the stent length in the abdominal cavity, we recently performed EUS-HGS using the technique of releasing the stent within the scope channel., Aims: To examine the technical feasibility of the intra-scope channel stent release technique., Methods: Forty-one consecutive patients who underwent EUS-HGS were enrolled. Between October 2015 and December 2015, EUS-HGS was performed using the extra-scope channel release technique, while the intra-scope channel release technique was performed between January 2016 and March 2016., Results: The distance between the hepatic parenchyma and the stomach wall after EUS-HGS in the intra-scope channel stent release group was significantly shorter than that in the extra-scope channel release group (0.66 ± 1.25 vs 2.52 ± 0.97, P < 0.05). Adverse events, such as biloma or stent migration, were seen in only the extra-scope channel release group., Conclusion: In conclusion, although additional cases and randomized controlled studies using metal stents of various lengths are needed, our technique is likely to be clinically useful for the prevention of early and late stent migration.

Introduction: Stent migration is a significant clinical problem in palliation of malignant strictures in the esophagus and gastro-esophageal junction (GEJ). We have compared a newer design of a fully-covered stent to a widely used semi-covered stent using migration >20 mm as the primary outcome variable. Effects on dysphagia, quality of life (QoL) and re-intervention frequency were also investigated., Methods: Patients with dysphagia due to non-curable esophagus/GEJ cancer were randomized to receive either a more recent design of a fully-covered stent (n = 48) or a conventional semi-covered stent (n = 47). Chest x-ray, dysphagia and QoL were studied at baseline, one week, four weeks and three months thereafter., Results: There were no significant differences either in stent migration distance or in the migration frequency. Stent migration during the total study period occurred in 37.2 % in the semi-covered group compared to 20.0 % for the fully-covered group. Dysphagia was measured with Watson and Ogilvie scores and with the dysphagia module in the QoL scale (QLQ-OG25). On average, there was a tendency to better dysphagia relief for the fully-covered design as scored with the two latter dysphagia instruments (p= 0.081 and p= 0.067) at three months and towards more re-interventions in the semi-covered group (p= 0.083)., Conclusion: In spite of its somewhat lower intrinsic radial force, the fully-covered stent was comparable to the conventional semi-covered stent with regard to stent migration. The data further suggest a potential benefit of the fully-covered stent in improving dysphagia in patients with longer life expectancy.

Background: Venous stents are commonly placed to ensure patency in patients with chronic peripheral venous insufficiency. Although serious complications are uncommon, peripheral venous stent placement can have some potentially life-threatening complications. One of the most feared, and certainly the most dramatic, complication is stent migration., Case Report: We report on a 55-year-old woman with transvenous migration of an infrarenal inferior vena cava stent into the right atrium and through the intra-atrial septum. The patient expired in the emergency department (ED). WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: There are several potentially life-threatening post-surgical complications after an endovascular procedure, some of which occur shortly after the patient is discharged from the recovery unit. Frequently, these patients present to the ED for initial evaluation. Although details of the procedure performed and the surgical intervention might not be available immediately, emergency physicians should consider stent migration when a patient presents in extremis shortly after an endovascular procedure., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Nutcracker syndrome is a clinical entity leading to renal venous hypertension due to extrinsic compression of the left renal vein by the superior mesenteric artery. Current surgical therapy involves placement of an oversized renal vein stent with partial protrusion into the inferior vena cava (IVC) to relieve stenosis and prevent stent migration. Here, we present a patient with intractable pain and hematuria secondary to nutcracker syndrome who underwent left renal vein stent placement and developed recurrent symptoms due to flow-limiting kinking at the left renal hilum, with partial obstruction of the IVC from pseudointimal hyperplasia. This was treated with stent excision and construction of a left neorenal vein bypass. Thus, given these complications, we should perhaps revisit the recommendations for oversizing of the stent.

Background/aim: In research and development of biliary plastic stents (PS), continuous efforts have been made to overcome short patency time and high rate of migration. The aim of this study was to evaluate the patency and migration rate of different PS shapes for a given period of time., Methods: Using an in vitro bile phantom model, we compared the patency among different shapes of PS (three straight PS, four double-pigtail PS, and a new screw-shaped PS). We performed an analysis of the degree of luminal narrowing by light microscopic examination. Using an in vivo swine model, we compared the patency and migration rate among the three different types of PS., Results: Eight weeks after the bile exposure in the bile flow phantom model, 80 PS were retrieved and analyzed. The straight PS showed less biofilm formation and luminal narrowing than other types of PS (p < 0.05). Forty-nine PS were inserted into the dilated bile ducts of 10 swine models, and 39 PS were successfully retrieved 8 weeks later. The stent migration occurred less frequently in the double-pigtail PS and the screw-shaped PS than it did in the straight PS (11.1, 10, and 27.3%, respectively). However, there was no statistical difference in stent patency among the different shapes., Conclusions: Stent patency may not be significantly different depending on the shape of PS for 8 weeks. The screw-shaped PS showed similar patency and migration rate to the double-pigtail PS. These results may help guiding future PS development and clinical decisions.

Stent migration is a complication associated with endovascular coil embolization of intracranial aneurysms. We report a case of anterior communicating artery (ACoA) aneurysm that was successfully treated after stent migration during endovascular coil embolization without retrieval of the stent. A 47-year-old man presented with sudden onset severe headache. Patient was noted to have subarachnoid hemorrhage from a ruptured ACoA aneurysm. Emergency endovascular coil embolization was performed. The second coil embolization was scheduled for the neck-remnant portion with a stent after 16 days from the initial operation. At first, a stent was deployed from the right perpendicular division of anterior cerebral artery (A2) to the left horizontal division of anterior cerebral artery (A1) entirely across the aneurysmal neck. Although the stent position looked fine, the stent migrated inferiorly to the proximal A1 portion when its delivery wire was withdrawn. Fortunately, the stent could be pushed into the distal A1 portion, when we trying to re-access the aneurysm thorough the stent with a pig-tail shaped microguidewire. Additional coil embolization was achieved using the assistance of distal tip of the stent as a scaffold of the coil. The patient was discharged without any complication on the postoperative day 6. Although there are various choices of rescue treatment after stent migration, this is the first reported case of stent repositioning with a microguidewire. Our technique may represent an effective option in case of stent migration.

Esophageal stent placement has significantly improved the quality of life in patients with malignant as well as benign esophageal obstructing lesions. Despite its early success and rapid adoption, stent migration still occurs in as many as 30% of cases especially with fully covered stents. To date, few models of interaction between the stent and the esophageal wall have been published and these have only focused on the deployment of the stent or the static mechanical stress distribution of the stent material. To elucidate the mechanism behind esophageal stent migration we developed a simplified radially symmetric computational model of esophageal peristalsis and the stent. A thorough review of the literature on esophageal peristalsis was performed and pertinent data were implemented into the model. Similarly, mechanical properties of an existing esophageal stent were used for the stent model. A sensitivity analysis of the parameters of the model enabled identification of the key elements of stent design that influence the degree of stent migration including flares design, stent length as well as longitudinal and radial stiffness. A comparison of the model to the migration rate reported in clinical studies for various types of fully covered stents further verified our model, which can significantly contribute to the development of a more stable esophageal stent with lower rates of migration., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: To determine the efficacy of retrievable metallic stent with fixation string for benign anastomotic stricture after upper gastrointestinal (UGI) surgery., Materials and Methods: From June 2009 to May 2015, a total of 56 retrievable metallic stents with fixation string were placed under fluoroscopy guidance in 42 patients who were diagnosed with benign anastomotic stricture after UGI surgery. Clinical success was defined as achieving normal regular diet (NRD)., Results: The clinical success rate after the first stent placement was 57.1% (24/42). After repeated stent placement and/or balloon dilation, the clinical success rate was increased to 83.3% (35/42). Six (14.3%) patients required surgical revision to achieve NRD. One (2.4%) patient failed to achieve NRD. Stent migration occurred in 60.7% (34/56) of patients. Successful rate of removing the stent using fixation string and angiocatheter was 94.6% (53/56). Distal migration occurred in 12 stents. Of the 12 stents, 10 (83.3%) were successfully removed whereas 2 could not be removed. No complication occurred regarding distal migration., Conclusion: Using retrievable metallic stent with a fixation string is a feasible option for managing early benign anastomotic stricture after UGI surgery. It can reduce complications caused by distal migration of the stent.

Background and Aims: Spontaneous intestinal migration of pancreatic stents is a known phenomenon. However, retrieval of a proximally migrated pancreatic stent (PMPS) poses a therapeutic challenge. The primary aim of this study was to evaluate technical success of endoscopic retrograde of cholangiopancreatography (ERCP) for extraction of PMPS, including number of sessions, need of surgery for failures and intervention-induced adverse events. The secondary outcome was to evaluate long-term effects of PMPS on the ductal morphology., Methods: Data of patients undergoing pancreatic stenting since January 2007 was reviewed. Fourteen patients were found to have PMPS. The level of stent migration was divided into two categories: level 1: retropapillary migration of the stent, the distal end seen till the genu (n = 6). Level II: PMPS with distal end seen beyond genu (n = 8). The stents were placed due to following reasons, prophylactic pancreatic stenting after common bile duct stone extraction (n = 6), pancreatic endotherapy for chronic pancreatitis (n = 7), and recurrent acute pancreatitis with incomplete pancreas divisum (n = 1). ERCP was done using Olympus TJF 160/180 duodenoscope. Stent extraction was initially attempted using rat tooth forceps, snare with or without wire, wire-guided basket, and in case of failures, pancreatoscope was used (Boston Scientific, USA)., Results: PMPS could successfully be retrieved in 13 out of 14 patients (92.8 %). Stents were retrieved using stone extraction balloon in two (14.2 %), modified angiography balloon in one (7 %), rat tooth in three patients (21.4 %), over-the-wire snare in three patients (21.4 %), lasso technique in one (7 %), and under pancreatoscope guidance in three patients (21.4 %). Adverse events encountered were mild pancreatitis (n = 2, 14 %) and self-limited bleeding (n = 2, 14 %)., Conclusions: Endotherapy of PMPS could be complex and associated with adverse events. Level II-migrated stents may require specialized methods like pancreatoscopy for stent retrieval.

We would like to report our experience of a rather rare complication that occurred in a 76-year old patient tree years after endovascular repair of a splenic artery pseudoaneurysm with a covered stent. Three years after stent insertion, the patient complained of mild abdominal pain and melena; it was revealed endoscopically that the covered stent has eroded the stomach wall and migrated into the stomach. The splenic artery is the most common location among the spectrum of potential presentation sites of visceral arteries aneurysms and pseudoaneurysms. Endovascular treatment with the use of coils or stents is the first option due to lower morbidity and mortality than open surgery. Endovascular repair may also lead to complications and patients need to be followed up in order to confirm aneurysm sealing, and exclude late complication. Minor stent graft migration may occur in the long term, however extra vascular migration is extremely rare.

Objective: Covered self-expandable metal stents (SEMSs) are increasingly used as alternatives to uncovered SEMSs for the palliation of inoperable malignant distal biliary obstruction to counteract tumor ingrowth. We aimed to compare the outcomes of partially covered and uncovered SEMSs with identical mesh structures and anti-migration properties, such as low axial force and flared ends., Materials and Methods: One hundred and three patients who were diagnosed with inoperable malignant distal biliary obstruction between January 2006 and August 2013 were randomly assigned to either the partially covered (n = 51) or uncovered (n = 52) SEMS group., Results: There were no significant differences in the cumulative stent patency, overall patient survival, stent dysfunction-free survival and overall adverse events, including pancreatitis and cholecystitis, between the two groups. Compared to the uncovered group, stent migration (5.9% vs. 0%, p = 0.118) and tumor overgrowth (7.8% vs. 1.9%, p = 0.205) were non-significantly more frequent in the partially covered group, whereas tumor ingrowth showed a significantly higher incidence in the uncovered group (5.9% vs. 19.2%, p = 0.041). Stent migration in the partially covered group occurred only in patients with short stenosis of the utmost distal bile duct (two in ampullary cancer, one in bile duct cancer), and did not occur in any patients with pancreatic cancer., Conclusions: For the palliation of malignant distal biliary obstruction, endoscopic placement of partially covered SEMSs with anti-migration designs and identical mesh structures to uncovered SEMSs failed to prolong cumulative stent patency or reduce stent migration.

Background and Aim: Covered metallic stents (CMSs) were developed to overcome tumor ingrowth in uncovered metallic stents (UMSs) for malignant biliary obstruction, but superiority of CMSs over UMSs is still controversial due to the high migration rate in CMS. Therefore, we conducted this retrospective analysis to clarify risk factors for stent migration, including mechanical properties of CMSs., Methods: Patients with unresectable pancreatic cancer, receiving CMS for distal malignant biliary obstruction in five tertiary care centers, were retrospectively studied. Univariate and multivariate analyses to identify prognostic factors for early (< 6 months) stent migration were performed using a proportional hazards model with death or stent occlusion without stent migration as a competing risk. Two mechanical properties were included in the analysis: axial force, the recovery force that leads to a CMS straightening, and radial force (RF), the expansion force against the stricture., Results: Among 290 patients who received CMS placement for distal malignant biliary obstruction, stent migration rate was 15.2%. CMS migrated early (< 6 months) in 10.0% and distally in 11.7%, respectively. In the multivariate analysis, significant risk factors for early stent migration were chemotherapy (subdistribution hazard ratios [SHR] 4.46, P = 0.01), CMS with low RF (SHR 2.23, P = 0.03), and duodenal invasion (SHR 2.25, P = 0.02)., Conclusion: CMS with low RF, chemotherapy, and duodenal invasion were associated with CMS migration from our study., (© 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.)

We assessed the frequency and severity of changes in stent configuration and location after the treatment of intracranial aneurysms, and patterns of in-stent stenosis. We retrospectively reviewed data for consecutive aneurysm patients managed with endovascular implantation of flow-diverter stents (Silk Flow Diverter [Balt Extrusion, Montmorency, France] and Pipeline Embolization Device [ev3/Coviden, Minneapolis, MN, USA]) from October 2011 to July 2012. Routine 2, 6, 9-12, and 16-20 month follow-up angiograms were compared, with a focus on changes in stent configuration and location from immediately after deployment to angiographic follow-up, and the incidence and development of in-stent stenosis. Thirty-four patients with 42 aneurysms met inclusion criteria. The Silk device was implanted in 16 patients (47%, single device in 15), the Pipeline device in 18 (53%, single device in 16). On first follow-up angiography, in-stent stenosis was observed in 38% of Silk devices and 39% of Pipeline devices. In-stent stenosis was asymptomatic in 12 of 13 patients. One woman presented with transient ischemic attacks and required stent angioplasty due to end tapering and mild, diffuse in-stent stenosis. Configuration and location changes, including stent creeping and end tapering were seen in 2/16 patients (13%) with Silk devices, and 0/18 patients with Pipeline devices. We describe stent creeping and end tapering as unusual findings with the potential for delayed clinical complications. In-stent stenosis, with a unique behavior, is a frequent angiographic finding observed after flow-diverter stent implant. The stenosis is usually asymptomatic; however, close clinical and angiographic monitoring is mandatory for individualized management., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Endoscopic pancreatic stenting (EPS) is used for various pancreatic conditions. With the increasing use of pancreatic stents, many complications have been observed. Especially, proximal stent migration presents a more serious condition because of the possibility of pancreatic duct (PD) damage. However, the removal of proximally migrated stents is technically challenging because of the small PD diameter, the bended PD course, the presence of PD strictures, and the lack of suitable devices for stent removal. Thus, few cases of surgical intervention have been encountered. In this study, we review the endoscopic treatment of proximally migrated pancreatic plastic stents. We classify migrated stent conditions into four types according to stent and PD conditions. In Type A, the main pancreatic duct (MPD) has no stricture. In Type B, the stent is positioned across the stricture on the MPD. In Type C, the stent is positioned further away from the stricture on the MPD. The tip of the proximal stent is located in the MPD in types A thru C. In Type D, the tip of the proximal stent is located in a branch duct. We introduced the strategy of endoscopic removal technique of each type of migrated plastic stents., (© 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: Removal of biliary Fully Covered Self Expandable Metal Stents can fail due to stent migration and/or hyperplastic ingrowth/overgrowth., Methods: A case series of 5 patients with benign biliary strictures (2 post-cholecystectomy, 2 following liver transplantation and 1 related to chronic pancreatitis) is reported. The biliary stricture was treated by temporary insertion of Fully Covered Self Expandable Metal Stents. Stent removal failed due to proximal stent migration and/or overgrowth. Metal stent removal was attempted a few weeks after the insertion of another Fully Covered Metal Stent into the first one., Results: The inner Fully Covered Self Expandable Metal Stent compressed the hyperplastic tissue, leading to the extraction of both the stents in all cases. Two complications were reported as a result of the attempt to stents removal (mild pancreatitis and self-limited haemobilia)., Conclusion: In the present series, the "SEMS in SEMS" technique revealed to be effective when difficulties are encountered during Fully Covered Self Expandable Metal Stents removal., (Copyright © 2014 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Endoscopic esophageal stent placement is widely used in the treatment of a variety of benign and malignant esophageal conditions. Self expanding metal stents (SEMS) are associated with significantly reduced stent related mortality and morbidity compared to plastic stents for treatment of esophageal conditions; however they have known complications of stent migration, stent occlusion, tumor ingrowth, stricture formation, reflux, bleeding and perforation amongst others. A rare and infrequently reported complication of SEMS is stent fracture and subsequent migration of the broken pieces. There have only been a handful of published case reports describing this problem. In this report we describe a case of a spontaneously fractured nitinol esophageal SEMS, and review the available literature on the unusual occurrence of SEMS fracture placed for benign or malignant obstruction in the esophagus. SEMS fracture could be a potentially dangerous event and should be considered in a patient having recurrent dysphagia despite successful placement of an esophageal SEMS. It usually requires endoscopic therapy and may unfortunately require surgery for retrieval of a distally migrated fragment. Early recognition and prompt management may be able to prevent further problems.

Interventional internal drainage of the biliary tract has become an established procedure for both the temporary and definitive treatment of biliary obstruction due to malignant or benign disease. Biliary stent migration and stent fracture are known but rare complications. A 50-year-old man presented with acute onset pain in the abdomen and vomiting. He had undergone hepaticojejunostomy following a bile duct injury during open cholecystectomy 13 years before he presented at our institution. Subsequently, he developed a benign biliary stricture at the anastomotic site, which was stented transhepatically by a metallic stent. CT of his abdomen showed a fractured stent segment obstructing the jejunum with a localized perforation. Herein, we discuss his presentation and course of management, and review the factors influencing stent migration and fracture and the potential options for stent retrieval. The patient needed surgical intervention to retrieve the migrated fragment of metal stent and to resect the perforated jejunal segment. The role of endoscopic self-expanding metal stents for benign biliary disease remains controversial. A migrated stent that has become symptomatic should be removed endoscopically in early and accessible cases and surgically when endoscopic measures fail or when complicated by obstruction or perforation., (© 2013 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.)

Abstract Double‐pigtail stents are commonly used for drainage in cholangitis to prevent stent migration. We report a case in which a double pigtail stent had migrated proximally into the bile duct and was successfully retrieved after endoscopic papillary large balloon dilatation (EPLBD). An 86‐year‐old man underwent endoscopic papillary sphincterotomy for cholangitis due to common bile duct stones and had a double‐pigtail stent placed in the common bile duct. The patient presented a week later for endoscopic biliary stone removal, but the stent had migrated proximally and could not be visualized during the endoscopy. Endoscopic papillary large balloon dilatation was performed to dilate the papilla to a diameter of 12 mm, following which the stent was grasped and removed. The biliary calculi were subsequently extracted, and the procedure was completed without any complications. This case highlights the potential usefulness of endoscopic papillary large balloon dilatation for retrieving a double‐pigtail stent that has migrated to the bile duct.

The aim of this study is to compare endoscopic stent suture fixation with endoscopic clip attachment or the use of partially covered stents (PCS) regarding their capability to prevent stent migration during prolonged dilatation in achalasia. Large-diameter self-expanding metal stents (30 mm × 80 mm) were placed across the gastroesophageal junction in 11 patients with achalasia. Stent removal was scheduled after 4 to 7 days. To prevent stent dislocation, endoscopic clip attachment, endoscopic stent suture fixation, or PCS were used. The Eckardt score was evaluated before and 6 months after prolonged dilatation. After endoscopic stent suture fixation, no (0/4) sutured stent migrated. When endoscopic clips were used, 80% (4/5) clipped stents migrated (p = 0.02).Of two PCS (n = 2), one migrated and one became embedded leading to difficult stent removal. Technical adverse events were not seen in endoscopic stent suture fixation but were significantly correlated with the use of clips or PCS (r = 0.828, p = 0.02). Overall, 72% of patients were in remission regarding their achalasia symptoms 6 months after prolonged dilatation. Endoscopic suture fixation of esophageal stents but not clip attachment appears to be the best method of preventing early migration of esophageal stents placed at difficult locations such as at the naive gastroesophageal junction. [ABSTRACT FROM AUTHOR]

Permanent metal stent placement for malignant intestinal obstruction has been proven to be efficient. Temporary stents for benign conditions of the colon and rectum are less studied. This is a case study, review of the literature, and observation from an animal model on placement of stents in the colorectum for benign disease. A 55-year-old man presented with recurrent obstructions from a benign stricture of the distal sigmoid colon. After failed balloon dilations, a polyester coated stent was placed. The purpose of the stent was to improve symptoms and avoid surgery. The stent was expelled after 5 days. We conducted a literature review of stents placed for benign colorectal strictures and an animal study to evaluate stent migration. In the literature, there were 53 reports of uncovered metal stents, four covered metal stents, and six polyester stents. Patency rates were 71%, and migration rate was 43%. Migration occurred earlier with polyester stents (mean = 8 days) versus covered (32 days) or uncovered metal stents (112 days). Severe complications were seen in 23% of patients. Four 45-kg pigs underwent rectosigmoid transection with a 21-mm anastomosis and endoscopic placement of a Polyflex stent. Two stents were secured with suture. Stents without fixation were expelled within 24 h of surgery. Stents with fixation were expelled between postoperative days 2 and 14. Stents for the treatment of benign colorectal strictures are safe, with comparable patency rates between stent types. Metal stents can cause severe complications. In a pig model, covered polyester stents tend to migrate early even with fixation. Further investigation needs to focus on new stent designs and/or better fixation. [ABSTRACT FROM AUTHOR]

Palliative stenting of malignant colonic obstruction may be complicated by stent migration. Stents that migrate into the rectum cannot be passed with bowel movements and frequently cause obstruction. We present two simple means to retrieve stents from the rectum using fluoroscopic guidance. These techniques were used successfully without complication in four stent migrations. [ABSTRACT FROM AUTHOR]