Conventional Metal Stents Research Articles

Past and Recent Progress on Metallic Digestive Tract Stents.

The implantation of digestive tract stents at various lesion sites can effectively improve digestive tract patency, opening up an excellent treatment method for diseases that are currently incurable or resistant to conventional surgery. Digestive tract stents have been extensively studied and widely used worldwide due to their unique advantages of simple implantation, low trauma, satisfactory effect, and low complication rate. Among the various types of stents, metallic stents have been developed to improve surgical efficacy due to their excellent mechanical properties and are constantly being improved. This review provides an overview of the design and development of conventional nonbiodegradable metallic digestive tract stents such as nitinol (NiTi alloy), stainless steel, and cobalt-based alloy stents. Furthermore, biodegradable metallic stents for the digestive tract, such as magnesium-based, iron-based, and zinc-based stents, are described. This paper also evaluates the advantages and disadvantages of existing metallic digestive stents as well as future research directions and challenges in the development of metallic digestive tract stents.

Five-Year Outcomes of Bioresorbable Stent Therapy for Coronary Heart Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

The efficacy of bioresorbable vascular scaffolds (BVS) compared to metallic stents for the treatment of coronary heart disease remains controversial. The analysis of clinical outcomes at five years following the initial treatment has yet to be reviewed. This study sought to assess the five-year outcomes in randomized controlled trials of BVS in the treatment of coronary heart disease using a systematic review and meta-analysis. A systematic database search was conducted from their inception to June 30th, 2023 using various Medical Subject Headings (MeSH) terms including: "Coronary Disease", "Bioresorbable stent", "Randomized controlled trials". After a rigorous selection process, a total of five high-quality articles were finally included in this study. Each trial demonstrated a low risk of bias. After 5 years, bioresorbable stents showed outcomes similar to conventional metal stents in terms of cardiac mortality. However, they were inferior in terms of lesion revascularization rates, in-stent thrombosis rates, target lesion failure, target vessel failure, and myocardial infarction. While bioresorbable stents are comparable to metallic stents in terms of cardiac mortality rates, they exhibit significant drawbacks that warrant clinical consideration.

Outcomes of two types of iodine-125 seed delivery with metal stents in treating malignant biliary obstruction: a systematic review and meta-analysis.

To conduct a meta-analysis comparing the efficacy and safety of two types of iodine-125 (I-125) seed delivery with metal stents (the study group) versus conventional metal stents (the control group) in patients with malignant biliary obstruction (MBO). Our team systematically searched the PubMed, Embase, and Cochrane Library databases for relevant studies published from January 2012 up to July 2021. Survival time and stent dysfunction were the primary measured outcomes. Subgroup analyses were conducted according to the type of I-125 seed delivery. Eleven studies, including 1057 patients in total, were pooled for stent dysfunction. The study group showed a lower risk of stent dysfunction than the control group [odds ratio (OR): 0.61, 95% confidence interval (CI) 0.46-0.81, P = 0.001]. The pooled results of six studies reporting overall survival (OS) showed that the study group had a better survival outcome than the control group [hazard ratio (HR): 0.34, 95% CI: 0.28-0.42, P < 0.001]. In the subgroup analyses, the I-125 seed stent group had significantly less stent dysfunction than the control group (OR: 0.49, 95% CI: 0.31-0.76, P = 0.002). Meanwhile, the metal stents + I-125 radioactive seed strand group showed significantly more improvement in OS than the control group (HR: 0.33, 95% CI: 0.26-0.42, P < 0.001). Moreover, our analysis suggests that using I-125 seeds did not result in increasing related adverse events compared with using metal stents alone (all P > 0.05). The study group was significantly superior to the control group, with better survival and decreased stent dysfunction. Meanwhile, the delivery of I-125 seeds did not increase adverse events. The delivery of I-125 with metal stents may be considered a preferable technique for MBO.

Anti-reflux versus conventional self-expanding metal stents in the palliation of esophageal cancer: A systematic review and meta-analysis.

Background and study aims Self-expanding metal stents (SEMS) are an effective palliative endoscopic therapy to reduce dysphagia in esophageal cancer. Gastroesophageal reflux disease (GERD) is a relatively common complaint after non-valved conventional SEMS placement. Therefore, valved self-expanding metal stents (SEMS-V) were designed to reduce the rate of GERD symptoms. We aimed to perform a systematic review and meta-analysis comparing the two stents. Material and methods This was a systematic review and meta-analysis including only randomized clinical trials (RCT) comparing the outcomes between SEMS-V and non-valved self-expanding metal stents (SEMS-NV) following the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The risk of bias was assessed using the Cochrane Risk of Bias 2 tool. Data were analyzed with Review Manager Software. Quality of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation guidelines. Results Ten randomized clinical trials including a total of 467 patients, 234 in the SEMS-V group and 233 in the SEMS-NV group, were included. There were no statistically significant differences regarding GERD qualitative analysis (RD –0.17; 95 % CI –0.67, 0.33; P = 0.5) and quantitative analysis (SMD –0.22; 95 % CI –0.53, 0.08; P = 0.15) technical success (RD –0.03; 95 % CI –0.07, 0.01; P = 0.16), dysphagia improvement (RD –0.07; 95 % CI –0.19, 0.06; P = 0.30), and adverse events (RD 0.07; 95 % CI –0.07, 0.20; P = 0.32). Conclusions Both SEMS-V and SEMS-NV are safe and effective in the palliation of esophageal cancer with similar rates of GERD, dysphagia relief, technical success, adverse events, stent migration, stent obstruction, bleeding, and improvement of the quality of life.

Utility of Fine-Gauge Balloon Catheter for EUS-Guided Hepaticogastrostomy.

Background and Purpose: During endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS), tract dilation is one of the most important steps, and the placement of conventional metal stents with 8.5 Fr delivery devices is difficult due to the large outer shape of the device. Fine-gauge balloon catheters have become popular because of their stricture penetration ability and ease of dilation. This study aimed to evaluate the utility of fine-gauge balloon catheters. Patients and Methods: This retrospective study involved 38 patients who underwent conventional metal stent placement. The patients were classified into two groups: those who underwent dilation with a fine-gauge balloon catheter before initial metal stenting (balloon dilation group) and those who underwent bougie dilation only (non-balloon dilation group). We evaluated the stenting success rate after initial dilation and adverse events. Results: Seventeen and twenty-one patients were included in the balloon dilation and non-balloon dilation groups, respectively. The stenting success rate after initial dilation was 100% (17/17) in the balloon dilation group and 71.4% (15/21) in the non-balloon dilation group (p = 0.024). As adverse events, peritonitis was observed in one case (4.8%) in the balloon dilation group, and in three cases (14.3%) in the non-balloon dilation group (p = 0.613). Conclusions: Dilation using a fine-gauge balloon catheter before conventional metal stent with 8.5 Fr delivery device placement is considered effective in EUS-HGS.

Percutaneous biliary stent combined with brachytherapy using 125I seeds for treatment of unresectable malignant obstructive jaundice: A meta-analysis.

BACKGROUNDMalignant obstructive jaundice (MOJ) is a common pathologic manifestation of malignant biliary obstruction. Recently, several clinical trials have explored the clinical effectiveness of intraluminal 125I seed-based brachytherapy for MOJ patients, and various outcomes have been reported.AIMTo assess the efficacy and safety of percutaneous biliary stents with 125I seeds compared to conventional metal stents in patients with unresectable MOJ.METHODSA systematic search of English-language databases (PubMed, Embase, Cochrane Library, and Web of Science) was performed to identify studies published prior to June 2020 that compared stents with or without 125I seeds in the treatment of unresectable MOJ. The outcomes analyzed included primary outcomes (stent patency and overall survival) and secondary outcomes (complications and liver function parameters).RESULTSSix randomized controlled trials and four retrospective studies involving 875 patients were eligible for the analysis. Of the 875 included patients, 404 were treated with 125I seed stents, while 471 were treated with conventional stents. Unadjusted pooled analysis demonstrated that compared to conventional stents, 125I seed stents extended the stent patency time [hazard ratio (HR) = 0.36, 95% confidence interval (CI) = 0.28-0.45, P < 0.0001] and overall survival period (HR = 0.52, 95%CI = 0.42–0.64, P < 0.00001). Subgroup analyses based on the type of 125I seed stent and type of study design showed consistent results. However, there were no significant differences in the occurrence of total complications [odds ratio (OR) = 1.12, 95%CI = 0.75-1.67, P = 0.57], hemobilia (OR = 1.02, 95%CI = 0.45-2.3, P = 0.96), pancreatitis (OR = 1.79, 95%CI = 0.42-7.53, P = 0.43), cholangitis (OR = 1.13, 95%CI = 0.60-2.13, P = 0.71), or pain (OR = 0.67, 95%CI = 0.22-2, P = 0.47). In addition, there were no reductions in the levels of serum indices, including total bilirubin [mean difference (MD) = 10.96, 95%CI = -3.56-25.49, P = 0.14], direct bilirubin (MD = 7.37, 95%CI = -9.76-24.5, P = 0.4), alanine aminotransferase (MD = 7.52, 95%CI = -0.71-15.74, P = 0.07), and aspartate aminotransferase (MD = -4.77, 95%CI = -19.98-10.44, P = 0.54), after treatment. Publication bias was detected regarding the outcome overall survival; however, the conclusions were not changed after the adjustment.CONCLUSIONPlacement of stents combined with brachytherapy using 125I seeds contributes to a longer stent patency and higher overall survival than placement of conventional stents without extra complications or severe liver damage. Thus, it can be considered an effective and safe treatment for unresectable MOJ.

EUS-guided biliary interventions for benign diseases and unsuccessful ERCP - a prospective unicenter feasibility study on a large consecutive patient cohort.

Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for the treatment of biliary obstruction of any etiology. However, cannulation failure of the common bile duct (CBD) by ERCP occurs in 5-10%. Alternatives after a failed ERCP are re-ERCP by an expert endoscopist, percutaneous transhepatic cholangio drainage (PTCD), (balloon) enteroscopy-assisted ERCP, or surgery. Endoscopic ultrasonography-guided drainage of the bile ducts (EUS-BD) is becoming the standard of care in tertiary referral centers for cases of failed ERCP in patients with malignant obstruction of the CBD. In expert hands, EUS-guided biliary drainage has excellent technical/clinical success rates and lower complication rates compared to PTCD. Despite the successful performance of EUS-BD in malignant cases, its use in benign cases is limited. The aim of this study (design, systematic prospective clinical observational study on quality assurance in daily clinical practice) was to evaluate the efficacy and safety of EUS-BD in benign indications. Patients with cholestasis and failed ERCP were recruited from a prospective EUS-BD registry (2004-2020). One hundred and three patients with EUS-BD and benign cholestasis were extracted from the registry (nTotal = 474). Indications of EUS-BDs included surgically altered anatomy (n = 65), atypical bile duct percutaneous transhepatic cholangio orifice at the duodenal junction from the longitudinal to the horizontal segment (n = 1), papilla of Vater not reached due to the gastric outlet/duodenal stenoses (n = 6), papilla that cannot be catheterized (n = 24), and proximal bile duct stenosis (n = 7). The primary endpoint was technical and clinical success. Secondary endpoints were procedure-related complications during the hospital stay. 103 patients with EUS-BD and benign cholestasis were extracted from the registry (nTotal=474). Different transluminal access routes were used to reach the bile ducts: transgastric (n = 72/103); -duodenal (n = 16/103); -jejunal (n = 14/103); combined -duodenal and -gastric (n = 1/103). The technical success rate was 96 % (n = 99) for cholangiography. Drainage was not required in 2 patients; balloon dilatation including stone extraction was sufficient in 17 cases (16.5 %; no additional or prophylactic insertion of a drain). Transluminal drainage was achieved in n = 68/103 (66 %; even higher in patients with drain indication only) by placement of a plastic stent (n = 29), conventional biliary metal stents (n = 24), HotAXIOS stents (n = 5; Boston Scientific, Ratingen, Germany), Hanaro stents (n = 6; Olympus, Hamburg, Germany), HotAXIOS stents and plastic stents (n = 1), HotAXIOS stents and metal stents (n = 1) and metal stents and plastic stents (n = 2). Techniques for stone extraction alone (nSuccessful=17) or stent insertion (nTotal = 85; nSuccessful=85 - rate, 100 %) and final EUS-BD access pathway included: Rendezvous technique (n = 14/85; 16.5 %), antegrade internal drainage (n = 20/85; 23.5 %), choledochointestinostomy (n = 7/85; 8.2 %), antegrade internal and hepaticointestinostomy (n = 22/85; 25.9 %), hepaticointestinostomy (n = 21/85; 24.7 %), choledochointestinostomy and hepaticointestinostomy (n = 1/85; 1.2 %).The complication rate was 25 % (n = 26) - the spectrum comprised stent dislocation (n = 11), perforation (n = 1), pain (n = 2), hemorrhage (n = 6), biliary ascites/leakage (n = 3) and bilioma/liver abscess (n = 3; major complication rate, n = 12/68 - 17.6 %). Re-interventions were required in 19 patients (24 interventions in total). EUS-BD can be considered an elegant and safe alternative to PTCD or reoperation for failed ERCP to achieve the necessary drainage of the biliary system even in underlying benign diseases. An interventional EUS-based internal procedure can resolve cholestasis, avoid PTCD or reoperation, and thus improve quality of life. Due to the often complex (pathological and/or postoperative) anatomy, EUS-BD should only be performed in centers with interventional endoscopy/EUS experience including adequate abdominal surgery and interventional radiology expertise in the background. This enables adequately adapted therapeutic management in the event of challenging complications. It seems appropriate to conduct further studies with larger numbers of cases to systematize the approach and peri-interventional management and to successively develop specific equipment.

Bifunctional poly (l-lactic acid)/hydrophobic silica nanocomposite layer coated on magnesium stents for enhancing corrosion resistance and endothelial cell responses

Biodegradable magnesium (Mg)-based vascular stents can overcome the limitations of conventional permanent metallic stents, such as late in-stent restenosis and thrombosis, but still have difficulty retarding degradation while providing adequate mechanical support to the blood vessel. We incorporated silica nanoparticles surface-functionalized with hexadecyltrimethoxysilane (mSiNP) into a poly (l-lactic acid) (PLLA) coating as a physical barrier to disturb the penetration of the corrosive medium as well as a bioactive source that releases silicon ions capable of stimulating endothelial cells. The corrosion resistance and biocompatibility of this bifunctional PLLA/mSiNP nanocomposite coating were investigated using different weight ratios of mSiNP. The nanocomposite coating containing more than 10 wt% of the mSiNP (PLLA/10mSiNP and PLLA/20mSiNP) significantly delayed the corrosion of the Mg substrate and exhibited favorable endothelial cell responses, compared to the pure PLLA coating. Specifically, the calculated corrosion rates of PLLA/10mSiNP and PLLA/20mSiNP decreased by half, indicating the durability of the coating after immersion in simulated body fluid for 12 days. Based on the in vitro cellular response, the incorporation of the mSiNPs into the PLLA coating significantly improved the endothelial cell responses to the Mg substrate, showing better initial cell surface coverage, migration, and proliferation rate than those of pure PLLA. These results indicate that the PLLA/mSiNP nanocomposite coatings have significant potential to improve the corrosion resistance and vascular compatibility of biodegradable Mg-based vascular stents.

Development of a Prognostic Scoring System To Select Candidates for Irradiation Stent Implantation for Patients with Unresectable Biliary Tract Cancer

Background: Compared with conventional metal stent, irradiation stent can prolong the stent patency and the survival time of patients. We aimed to develop a predictive model to select appropriate candidates for irradiation stent implantation among patients with biliary obstruction caused by unresectable biliary tract cancer (BTC). Methods: The training cohort consisted of 130 patients from three centers, and an external independent center was allocated as the validation cohort with 43 patients. We constructed a prognostic nomogram and risk classification system to select appropriate patients with unresectable BTC for irradiation stent implantation. Findings: The C-index of the nomogram was 0·724 and 0·736 in the training cohort and validation cohort, respectively. The calibration curves showed good consistency of survival between the actual observation and nomogram prediction in both cohorts. A risk classification system was built to stratify patients into three risk strata. In the training cohort, the median survival of patients in the low-, intermediate-, and high-risk groups were 10·1 months (95% CI 9·1–11·1), 4·6 months (95% CI 3·6–5·6), and 1·5 months (95% CI 0·1–3·0), respectively. Interpretation: According to this newly developed predictive model, irradiation stents are highly recommended for patients in the low-risk group (score≤100) for long-term survival benefit but not recommended for those in the high-risk group (score≥166·5). Funding: This study was supported by the National Key Research and Development Project of China (2018YFA0704100), the National Natural Science Foundation of China (Major Scientific Research Instrument Development Program 81827805, 81441054, 81671796), Jiangsu Provincial Medical Youth Talent Program (ZDRCA2016078), the Key Research and Development Project of Jiangsu Province (BE2019750) and Innovation Platform of Jiangsu Provincial Medical Center (YXZXA2016005). Declaration of Interest: The authors have no conflicts of interest to declare. Ethical Approval: This multicenter retrospective study was approved by the institutional review boards at all participating centers. The requirement for written informed consent was waived due to the retrospective nature of the study.

Computational analysis of the effects of geometric irregularities and post-processing steps on the mechanical behavior of additively manufactured 316L stainless steel stents

Advances in additive manufacturing enable the production of tailored lattice structures and thus, in principle, coronary stents. This study investigates the effects of process-related irregularities, heat and surface treatment on the morphology, mechanical response, and expansion behavior of 316L stainless steel stents produced by laser powder bed fusion and provides a methodological approach for their numerical evaluation. A combined experimental and computational framework is used, based on both actual and computationally reconstructed laser powder bed fused stents. Process-related morphological deviations between the as-designed and actual laser powder bed fused stents were observed, resulting in a diameter increase by a factor of 2-2.6 for the stents without surface treatment and 1.3-2 for the electropolished stent compared to the as-designed stent. Thus, due to the increased geometrically induced stiffness, the laser powder bed fused stents in the as-built (7.11 ± 0.63 N) or the heat treated condition (5.87 ± 0.49 N) showed increased radial forces when compressed between two plates. After electropolishing, the heat treated stents exhibited radial forces (2.38 ± 0.23 N) comparable to conventional metallic stents. The laser powder bed fused stents were further affected by the size effect, resulting in a reduced yield strength by 41% in the as-built and by 59% in the heat treated condition compared to the bulk material obtained from tensile tests. The presented numerical approach was successful in predicting the macroscopic mechanical response of the stents under compression. During deformation, increased stiffness and local stress concentration were observed within the laser powder bed fused stents. Subsequent numerical expansion analysis of the derived stent models within a previously verified numerical model of stent expansion showed that electropolished and heat treated laser powder bed fused stents can exhibit comparable expansion behavior to conventional stents. The findings from this work motivate future experimental/numerical studies to quantify threshold values of critical geometric irregularities, which could be used to establish design guidelines for laser powder bed fused stents/lattice structures.

A novel combination of percutaneous stenting with iodine-125 seed implantation and chemotherapy for the treatment of pancreatic head cancer with obstructive jaundice

PurposeInsertion of radioactive strips through the biliary stent has been reported to offer longer survival and patency than an uncovered conventional self-expanding metal stent in patients with unresectable malignant biliary obstruction. The aim of this study was to investigate the safety and effectiveness of intraluminal brachytherapy combined with 125I seed implantation and transarterial infusion chemotherapy for the treatment of pancreatic head cancer with obstructive jaundice. MethodFrom October 2012 to January 2018, 21 consecutive patients diagnosed with biliary obstruction caused by locally advanced, nonmetastatic pancreatic cancer with cytologically or histologically confirmed by biopsy were enrolled and receive treatment with intraluminal brachytherapy using 125I seed strand and CT-guided percutaneous radioactive seed implantation therapy. The procedure-related and radiation complications were assessed. The outcomes were measured in terms of stent patency, patient survival, complications related to the procedure. ResultOne of the 22 patients (4.5%, 1/22) with pancreatic head cancer failed to perform the above procedure because the guidewire was unable to pass through the obstruction segment. The remaining 21 patients (95.5%, 21/22) with pancreatic head cancer with obstructive jaundice were successfully placed with biliary stents and radioactive strips through drainage tubes. The median number of 125I seeds loaded was 15, ranging from 12 to 17. After the chemotherapy with gemcitabine and cisplatin, no adverse reaction of Grade Ⅲ ∼ Ⅳ occurred in all cases. Median stent patency was 12.50 months (95% CI: 10.26, 14.74). By May 2019, all 21 patients had died, with overall survival of 5.2–23.3 months, with a median survival of 13.20 months (95% CI: 10.96, 15.44). ConclusionPercutaneous 125I seed implantation combined with insertion of radioactive strips through the biliary stent has the characteristics of less trauma, fewer complications, simple operation, and so on. These procedures bring remission of obstructive jaundice combined with the increased survival for the treatment of obstructive jaundice caused by unresectable pancreatic head cancer if follow-up chemotherapy is carried out. The long-term efficacy of this treatment combination needs to be confirmed by further multicenter, large sample size prospective randomized controlled studies.

898 Antireflux Valve Metal Stent vs. Conventional Self Expandable Metal Stent in Distal Malignant Biliary Obstruction: A Systemic Review and Meta-Analysis

INTRODUCTION: In patients with distal malignant biliary obstruction (MBO), endoscopic biliary drainage by using the conventional self-expandable metal stent (cSEMS) is the gold standard established method for palliative treatment. However, there are limited data on the role of the antireflux valve metal stent (ARVMS). The aim of this study is to compare the efficacy and safety of ARVMS and cSEMS. METHODS: We performed an electronic search including PubMed, MEDLINE, EMBASE and Cochrane Library following the Preferred Reporting Items for Systemic Review and Meta-analysis (PRISMA) from inception until April 2019. We included randomized controlled trials (RCTs) that studied the efficacy and safety of ARVMS vs cSEMS deployment in distal malignant biliary obstruction. The selected studies provided data regarding technical and clinical success rates. Adverse events and stent dysfunction were also analyzed. We assessed the risk of biases using Cochrane Collaboration tool to assess the risk of bias. RESULTS: A total of 3 RCT’s were selected, enrolling 293 patients (147 ARVMS and 146 cSEMS). The rate of technical success between the ARVMS and cSEMS groups was 95.23% and 99.31% [odds ratio (OR) 0.13; 95% Confidence Interval (95% CI) 0.01-1.06, P = 0.06]. The clinical success rate was 91.57% and 89.36% (OR: 1.30; 95% CI: 0.48-3.51, P = 0.61). There was no significant difference in terms of adverse events between ARVMS and cSEMS (OR: 0.61; 95% CI: 0.35-1.05, P = 0.07). Overall, there was no statistical significance in stent dysfunction (OR: 0.77; 95% CI: 0.48-1.24, P = 0.29), however; after performing sub analysis stent migration was significantly higher in ARVMS (OR: 2.76; 95% CI: 1.24-6.17, P = 0.01). Stent occlusion was significantly lower in ARVMS (OR: 0.44; 95% CI: 0.26-0.76, P = 0.003). CONCLUSION: Our study showed that ARVMS and cSEMS technical and clinical success rates were similar. Adverse events were comparable between two arms. ARVMS was associated with lower risk of stent occlusion. Further randomized controlled trials are required with a higher number of patient population to verify the benefit of ARVMS.

Percutaneous stenting and chemotherapy for unresectable pancreatic cancer: Comparison of irradiation stents vs conventional metal stents

ObjectivesPercutaneous stenting is a palliative method to relieve obstructive jaundice caused by unresectable pancreatic carcinoma. In this study, we aimed to compare the safety and efficacy of irradiation stents and conventional metal stents. MethodsA total of 32 patients who received irradiation stents or conventional metal stents to treat obstructive jaundice caused by locally advanced pancreatic cancer were included in this retrospective study. Chemotherapy using gemcitabine was performed after jaundice subsided. Stent patency, technical success, survival, and complications were compared between groups. ResultsSeventeen patients were enrolled in the irradiation stent group (ISG), and 15 patients were enrolled in the uncovered stent group (USG). Median and mean stent patency time were 9.8 months (95% CI, 7.682–11.981) and 9.506 months (95% CI, 8.0–11.012) in the ISG, respectively, vs 8.8 months (95% CI, 6.528–11.072) and 7.62 months (95% CI, 5.917–9.323) in the USG, respectively (P = 0.019). Median and mean overall survival were 10.4 months (95% CI, 8.383–12.417) and 9.953 months (95% CI, 8.408–11.498), respectively, in the ISG vs 9.7 months (95% CI, 7.901–11.499) and 8.14 months (95% CI, 6.44–9.84), respectively, in the USG (P = 0.027). ConclusionsIrradiation stents extend stent patency and overall survival compared with conventional biliary stents for the treatment of pancreatic carcinoma complicated by obstructive jaundice. Irradiation stents combined with chemotherapy may be a better choice for the treatment of obstructive jaundice caused by unresectable pancreatic carcinoma.

A novel gallbladder umbrella stent (the Shai™ Stent) for prevention of stone migration and impaction: results on feasibility and short-term safety in a porcine model.

Cholelithiasis is the most common biliary tract disorder. Surgery is the treatment of choice for symptomatic gallstones. Aims of this study were to investigate the feasibility and short-term safety of a new endoscopic procedure with a specially designed Nitinol gallbladder stent for blockage of gallstone migration, the Shai™ Stent. The Shai stent is designed to enable free bile flow, which will be supposed to prevent recurrent attacks. The Shai™ Stent was inserted into the gallbladder during a standard ERCP procedure using a conventional metal stent delivery system. The aim of the present study was to investigate the feasibility and safety of insertion and deployment and removal of the stent into the gallbladder of pigs. In addition, the short-term safety of the stent was evaluated. Fifteen stents were placed in the gallbladder of 15 pigs. Mean procedure time was 25min (15-37). The maximum follow-up before sacrifice was 42days. The stent in 1 pig had migrated at the 42days follow-up but there were no macroscopic changes in its gallbladder or other organs. The stent remained in place in the remaining 12 pigs at autopsy, and the gallbladder and bile ducts were macroscopically normal. Stent removal was easily done in two pigs immediately after placement. Correct placement and removal of the Shai™ Stent in the gallbladder is safe and feasible in pigs. Further clinical trials are warranted to confirm these results and to effectively evaluate the capability of this stent as an innovative biotechnology to block gallstones from migration and impaction.

Antireflux valve metal stent versus conventional self-expandable metal stent in distal malignant biliary obstruction: a systematic review and meta-analysis.

Background:In patients with distal malignant biliary obstruction (MBO), endoscopic biliary drainage using the conventional self-expandable metal stent (SEMS) is the gold standard method for palliative treatment. However, there are limited data on the role of the antireflux valve metal stent (ARVMS). The aim of this study was to compare the safety and efficacy of ARVMS and SEMS in patients with distal MBO.Methods:We searched PubMed, Ovid, Embase and the Cochrane Library from inception until April 2019 for relevant randomized controlled trials (RCTs). The selected studies provided data regarding technical and clinical success rates, adverse events, and stent dysfunction. Data were meta-analyzed using RevMan software.Results:Three RCTs were selected, enrolling 293 patients (147 ARVMS and 146 SEMS). The rates of technical success were 95.23% and 99.31% for ARVMS and SEMS groups, respectively (odds ratio [OR] 0.13, 95% confidence interval [CI] 0.01-1.06; P=0.06). The clinical success rates were 91.57% and 89.36% for ARVMS and SEMS groups, respectively (OR 1.30, 95%CI 0.48-3.51; P=0.61). There was no significant difference between the ARVMS and SEMS groups in terms of adverse events (OR 0.61, 95%CI 0.35-1.05; P=0.07) or stent dysfunction (OR 0.77, 95%CI 0.31-1.95; P=0.58), while the incidence of stent occlusion was significantly lower in the ARVMS group (OR 0.44, 95%CI 0.26-0.76; P=0.003).Conclusion:Our study showed that ARVMS and SEMS had similar technical and clinical success rates. Adverse events were comparable between the 2 arms; however, ARVMS was associated with a lower risk of stent occlusion. Larger RCTs are required to verify the benefit of ARVMS in distal MBO patients.

EUS-specific stents: Available designs and probable lacunae.

Interventional EUS has seen exponential growth in its indications and applications in the last decade.[1,2,3] Dedicated endoscopic devices for EUS-guided interventions are still limited. Up until recently, the tools used have been borrowed from other procedures such as ERCP. In interventional EUS, the linear-array echoendoscope allows a needle to be advanced under EUS-guidance from the upper gastrointestinal lumen to the biliary, pancreatic, or another adjacent intestinal lumen. Real-time puncture can be performed and provide the possibility of EUS-guided transluminal drainage (EUS-TLD). Plastic stents and conventional self-expandable metallic stents (SEMSs) were initially used but present several limitations due to their design.[1,4,5] They lack lumen-to-lumen anchorage and present migratory risks in the absence of stricture to hold them in place. Plastic stents are associated with potential pneumoperitoneum and bile peritonitis, whereas fully-covered SEMS (FCSEMS), despite preventing bile leak, will not maintain secure apposition between two nonadherent organs. Furthermore, their length often exceeds the anatomical requirement of a shorter transluminal anastomosis and predisposes them to obstruction as well as difficult positioning. With the rise in new EUS-guided interventional techniques, new tools, in particular, new stent designs have evolved to facilitate the various applications. A few EUS-specific stents have now become available for EUS-TLD.[4,5] We hereby review the stent designs and discuss lacunae to be addressed to improve the efficacy, safety, and ease of procedures.

Wireless pressure sensor integrated with a 3D printed polymer stent for smart health monitoring

The primary objective of this study was to deploy a promising wireless pressure sensor system capable of monitoring real-time biological signals in an experimental object. MEMS-based micromachining technology was used to fabricate the proposed SU-8 wireless pressure sensor. The sensor utilizes a capacitor-inductor resonant circuit that can operate the sensor without any external power supply. The variable capacitor in the pressure sensor is designed to change the resonance frequency (130, 183 MHz) in response to applied pressure. The fabricated wireless pressure sensor was integrated into a polymer-based smart stent to minimize the discomfort of medication administration and hospital visits. A 3D bio-printing-based manufacturing technique was employed for the production of a smart polymer stent with complicated shapes. The proposed method is considerably more comfortable than the conventional metal stents fabrication process. The polymer smart stent made of the biocompatible polycaprolactone (PCL) material which can be fully absorbed by the body after a medication period. After integrating the fabricated wireless pressure sensor with the polymer smart stent, various basic experiments such as the working distance of the sensor were performed using a simple experimental setup. The biocompatibility of the proposed polymer stent and the wireless pressure sensor was also successfully confirmed using an experimental animal. The preliminary investigation results indicate that the proposed wireless sensor can be used to obtain necessary information in various parts of the human body as well as the stent.

Preliminary clinical application of integrated 125I seeds stents in the therapy of malignant lower biliary tract obstruction.

To evaluate the clinical efficacy of percutaneous trans-hepatic integrated 125I seed stents implantation for malignant lower biliary tract obstruction. Thirty-two patients with malignant lower biliary obstruction were randomly divided into two groups. One group underwent the therapy with integrated 125I seed stents (Test group, n = 13), and another group received conventional metal stents implantation for treatment (Control group, n = 19). The pre- and post-operative changes in biochemical indices, white blood cell count, IgG level, stent patency, survival time, tumor size and complications were compared between the two groups. RECIST 1.1 (Response Evaluation Criteria In Solid Tumors) was used to evaluate therapeutic effects. The average follow-up time was 12.3 months. The differences between pre- and post-operative (30 days) intragroup biochemical indices had statistically significant difference (P < 0.05), but there were no significant differences (P > 0.05) in leukocyte counts and IgG levels. As to the median time of stent patency and patients' survival, there were significant differences (P < 0.05) between Control and Test groups (3.9 months vs. 8.1 months, 139 days vs. 298 days, respectively). Three months after the operation, the average tumor size was reduced in the Test group, but was increased in the Control group (P < 0.05). There was no significant difference in the incidence of complications between the two groups. The evaluation results using RECIST 1.1 showed that there were statistically significant differences between the two groups in terms of the rates of remission, control, and progression (χ2 = 17.5, P < 0.05). The study indicates that integrated 125I seed stents are effective in reducing jaundice symptoms, inhibiting tumor growth, improving stent patency and prolonging patient survival, which may serve as a safer and more feasible method in treating malignant lower biliary obstruction with minimal invasiveness.

The Evolution of EUS-Guided Transluminal Drainage for the Treatment of Pancreatic Fluid Collections: A Comparison of Clinical and Cost Outcomes with Double-Pigtail Plastic Stents, Conventional Metal Stents and Lumen-Apposing Metal Stents.

BackgroundWhile most pancreatic fluid collections (PFCs) resolve spontaneously, endoscopic ultrasound-guided transluminal drainage (EUS-TD) may be necessary. EUS-TD has evolved from multiple double-pigtail plastic stents (DPPS) to fully covered self-expanding metal stents (FCSEMS) and lumen-apposing metal stents (LAMS). This study compares clinical attributes of DPPS, FCSEMS and LAMS.MethodsThis is a single-centre retrospective review of EUS-TD for PFCs. The primary outcome was clinical success. Secondary outcomes were technical success, procedure time, hospital length of stay (HLOS), number of endoscopies, need for necrosectomy, adverse events (AEs) and overall cost.ResultsFifty-eight patients (37 male, average age 49 years) underwent a total of 60 EUS-TD procedures for PFCs (average size 11.2 cm with 29 pseudocysts and 29 walled-off necrosis). Ten patients (17%) underwent EUS-TD with DPPS and 48 patients (83%) with metal stents (32 FCSEMS, 16 LAMS). Overall technical and clinical success was 100% and 84%, respectively. Lumen-apposing metal stents had shorter procedure times (14.9 versus 63.6 DPPS, 39.1 min FCSEMS, P < 0.001), and no difference in AEs (3 of 16 versus 4 of 10 DPPS, 12 of 34 FCSEMS, ns). Double-pigtail plastic stents required more endoscopies (3.7 versus 2.3 LAMS, 2.3 FCSEMS, P = 0.013) and necrosectomies (4 of 10 [40%]) compared with 5 of 34 [15%] in the FCSEMS group and 3 of 16 [19%] in the LAMS group, respectively, P = 0.001) to achieve clinical resolution. The overall cost and HLOS was not significantly different between groups.ConclusionThe use of LAMS for PFCs is not associated with any significant increase in cost despite technical (shorter procedure time) and clinical advantages (shorter indwell time, reduced need for necrosectomy and no increase in AEs).

Su1401 FEASIBLITY AND SAFETY OF EUS-GUIDED GALLBLADDER DRAINAGE WITH NEW LUMEN APPOSING METAL STENT (SPAXUS) IN PATIENTS WITH ACUTE CHOLECYSTITIS WHO ARE UNSUITABLE FOR CHOLECYSTECTOMY

Endoscopic ultrasound (EUS) guided gallbladder drainage increasingly accepted as an effective alternative to percutaneous drainage in a patient who needs drainage for acute cholecystitis. Stent migration is the main obstacles in EUS guided gallbladder drainage (EUS-GBD) with conventional biliary metal stent. To overcome this adverse event, a lumen apposing metal stent (LAMS) has recently been introduced in this procedure. In this study, we have evaluated the feasibility and safety of newly developed LAMS (SPAXUS®) in patients with acute cholecystitis who were unsuitable for cholecystectomy. Between Mar 2017 to Oct 2017, a total of 22 patients with acute cholecystitis who did not respond to initial medical treatment and were unsuitable cholecystectomy were enrolled. We evaluated technical, clinical success and adverse event profiles. EUS-GBD with newly developed LAMS was technically and clinically successful in 21/22 patients. Mean procedure time was 12.5 ± 5.0 minutes. Purpose of EUS-GBD was urgent drainage in 17 and establish of internal drainage before percutaneous transhepatic gallbladder drainage (P-GBD) removal in 5 patients. Early adverse events were occurred in 2/21 patients (1 stent occlusion by stone and 1 pyloric ring obstruction by proximal flange of SPAXUS). In the cases with pyloric ring obstruction, pyloric stent was applied temporarily. In 10 patients, direct cholecystoscopy was conducted one or two days after EUS-GBD Late adverse event of stent occlusion developed in 1/21 patients. Stent migration was not observed during follow up period. P-GBD removal was possible in all 5 patients who underwent EUS-GBD for internal drainage before P-GBD removal. Mean stent patency duration was 162.5 days (95% CI 146.37-178-63). EUS-GBD with new lumen apposing metal stent is technically feasible and shows acceptable safety profile in patients with acute cholecystitis who has high surgical risk.