A pilot study of endoscopically inserted biodegradable biliary stents in the treatment of benign biliary strictures and cystic duct leaks

Management of Benign Biliary Stricture in Chronic Pancreatitis

Endoscopic therapy is the first line of management for chronic pancreatitis (CP)-related benign biliary strictures. Multiple plastic stents (MPS) exchanged at regular intervals and temporary placement of fully covered self-expanding metal stents (FCSEMS) are preferred modalities of endotherapy. FCSEMS placement is non-inferior to MPS and requires fewer sessions of endoscopic retrograde cholangiopancreatography than MPS placement. The presence of head calcifications, severe CP, and length of stricture are predictors of failure or recurrence after endotherapy. Failure of endotherapy should be considered after 1 year when surgery should be considered.

Biosynthetic Plastics as Tunable Elastic and Visible Stent with Shape-Memory to Treat Biliary Stricture

Common biliary tract is ≈4 mm in diameter to deliver bile from liver to small intestine to help digestion. The abnormal narrowing leads to severe symptoms such as pain and nausea. Stents are an effective treatment. Compared with non-degradable stents which require repeated removal, biodegradable stents have the advantage of reducing secondary injury related to endoscopic operation and patient burden. However, current biodegradable materials may cause tissue hyperplasia and the treatment method does not target etiology of stricture. So recurrence rates after biodegradable stent implantation are still high. Here, a biodegradable helical stent fabricated from biosynthetic P(3HB-co-4HB) is reported. Tunable properties can be acquired through altering culture substrates. Stent shows shape memory in various solvents. The stent has an optimized design with helical structure and outer track. The self-expanding of helical structure and double drainage realized by outer track greatly improve drainage of bile. Importantly, stent-loading triamcinolone acetonide can inhibit proliferation of fibroblasts and reduce incidence of restricture. Therapeutic effect is also demonstrated in minipigs with biliary stricture. The results of minipig experiments show that biliary duct in treatment group is unobstructed and tissue hyperplasia is effectively inhibited.

Biodegradable biliopancreatic stents could help conserve health care resources during the COVID-19 pandemic: An observational multicenter study

BACKGROUND

Considering limited resources for follow-up due to COVID-19, we used biodegradable stents (BPBS) for a range of biliopancreatic diseases.

AIMS

This observational multicenter study aimed to evaluate technical safety and give first insights into clinical utility.

METHODS

Technical success, clinical success, and necessity of follow-up visits for BPBS placed at three Austrian tertiary care hospitals between April 2020 and January 2021 were retrospectively analyzed.

RESULTS

63 stents were deployed in 60 patients. Main indications were prophylaxis of post-ERCP pancreatitis (PEP; n = 30/63; 48%) and bridging of prolonged waiting times to cholecystectomy (n = 21/63; 33%). Median time to surgery was 47 days (range: 136 days). The technical success rate was 94% (n = 59/63; 95% CI [0.84, 0.98]). Technical difficulties primarily arose with dislocations. Clinical success was achieved in 90% (n = 57/63; 95% CI [0.80, 0.96]). Clinical failure despite successful deployment was caused by papillary bleeding (1 patient) and cholestasis (1 patient). Both required reinterventions. No follow-up visits were needed in 97% of cases (n = 57/59; 95% CI [0.88, 1.00]).

CONCLUSION

Biodegradable stents could help conserve health care resources without compromising treatment standards for PEP prophylaxis, which is particularly valuable in times of restricted resources. First insights into feasibility as bridging to cholecystectomy indicate a favorable safety profile.

Post cholecystectomy benign biliary stricture-isolated hepatic duct stricture: a proposed modification of the BISMUTH classification

BACKGROUND

Post-cholecystectomy, benign biliary strictures are challenging for both patients and surgeons. Bismuth classified benign biliary strictures into 5 types. This study aimed to review these isolated hepatic duct strictures which were not included in Bismuth classification.

METHODS

The case records of all patients who presented with post-cholecystectomy benign biliary strictures between January 2005 and December 2020 at our centre were reviewed. Data regarding demography, type of stricture, and treatment strategy were entered into the standard proforma.

RESULTS

There were 242 patients [type I-3.7%, type II-41.7%, type III-38.0%, type IV-6.6%, and type V-7.8%]. Five (2.1%) patients did not fit the Bismuth classification and were the focus of this study. In each of these patients, an isolated hepatic duct stricture (first-or second-order hepatic duct) was present, with no involvement of the common hepatic duct or hilar confluence.

CONCLUSIONS

The addition of isolated hepatic duct stricture [type VI] to the Bismuth classification will enhance the original classification, help in reporting and management of this sub-set of patients.

Recent developments in antibacterial or antibiofilm compound coating for biliary stents

Cholestasis of the indwelling biliary stents usually leads to stone recurrence after endoscopic retrograde cholangio pancreatoraphy (ERCP). Biliary stents, including metallic and none-degradable plastic stents are widely used in clinical settings due to their many excellent properties. However, conventional biliary stents still suffer from poor antibacterial activity and anti-bile-adhesion, which lead to injured, local fibroblasts proliferating. Currently, various coatings for biliary stents have been prepared to meet the clinical demands. In this review, we start by summarizing and discussing classifications of biliary stents and antibacterial/antibiofilm mechanism. Then, the latest advances about developing antibacterial and antibiofilm coatings for improving the properties of biliary stents are reviewed and discussed in detail. Lastly, we list several possible directions for future development of biliary stents coatings and biliary stent, such as anti-bile-adhesion coating, multifunctional coating, drug-eluting biodegradable biliary stents and 3D printed biliary stents.

Feasibility and safety of a novel 3D-printed biodegradable biliary stent in an in vivo porcine model: a preliminary study

To assess the feasibility and safety of a novel 3D-printed biodegradable biliary stent using polycaprolactone (PCL) in an in vivo porcine model. In this animal study using domestic pigs, biodegradable radiopaque biliary stents made of polycaprolactone (PCL) and barium sulfate were produced using 3D printing and surgically inserted into the common bile duct (CBD) of pigs (stent group, n = 12). Another five pigs were allocated to the control group that only underwent resection and anastomosis of the CBD without stent insertion. To check the position and status of the stents and stent-related complications, follow-up computed tomography (CT) was performed every month. The pigs were sacrificed 1 or 3 months after surgery, and their excised CBD specimens were examined at both the macroscopic and microscopic levels. Three pigs (one in the stent group and two in the control group) died within one day after surgery and were excluded from further analysis; the remaining 11 in the stent group and 3 in the control group survived the scheduled follow-up period (1 month, 5 and 1; and 3 months, 6 and 2 in stent and control groups, respectively). In all pigs, no clinical symptoms or radiologic evidence of biliary complications was observed. In the stent group (n = 11), stent migration (n = 1 at 3 months; n = 2 at 1 month) and stent fracture (n = 3 at 2 months) were detected on CT scans. Macroscopic evaluation of the stent indicated no significant change at 1 month (n = 3) or fragmentation with discoloration at 3 months (n = 5). On microscopic examination of CBD specimens, the tissue inflammation score was significantly higher in the stent group than in the control group (mean ± standard deviation (SD), 5.63 ± 2.07 vs. 2.00 ± 1.73; P = 0.039) and thickness of fibrosis of the CBD wall was significantly higher than that of the control group (0.46 ± 0.12 mm vs. 0.21 ± 0.05 mm; P = 0.012). Despite mild bile duct inflammation and fibrosis, 3D-printed biodegradable biliary stents showed good feasibility and safety in porcine bile ducts, suggesting their potential for use in the prevention of postoperative biliary strictures.

A review on biodegradable biliary stents: materials and future trends

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements，although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

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Summary of current development status of bioresorbable biliary stents with the emphasis on the stent materials.

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The future development trends based on the published literature.

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The advantages of bioresorbable biliary stents compared with metallic and plastic biliary stents.

Futuristic Developments and Applications in Endoluminal Stenting

Endoscopic stenting is a well-established option for the treatment of malignant obstruction, temporary management of benign strictures, and sealing transmural defects, as well as drainage of pancreatic fluid collections and biliary obstruction. In recent years, in addition to expansion in indications for endoscopic stenting, considerable strides have been made in stent technology, and several types of devices with advanced designs and materials are continuously being developed. In this review, we discuss the important developments in stent designs and novel indications for endoluminal and transluminal stenting. Our discussion specifically focuses on (i) biodegradable as well as (ii) irradiating and drug-eluting stents for esophageal, gastroduodenal, biliary, and colonic indications, (iii) endoscopic stenting in inflammatory bowel disease, and (iv) lumen-apposing metal stent.

Emerging Trends in Biliary Stents: A Materials and Manufacturing Perspective

Biliary stent technology has come a long way since its inception. There have been significant advancements in materials used, designs, and deployment strategies. Options have expanded from thermoplastic and metallic...

Plastic or self-expandable metal stent: Which is the most suitable for patients with pancreatic head cancer in the upcoming era of neoadjuvant chemotherapy? A review

Obstructive jaundice is a major symptom of pancreatic head cancer, and although its amelioration is required before scheduling chemotherapy, the decision to perform biliary drainage for resectable pancreatic cancer has remained controversial. In recent years, the effectiveness of neoadjuvant therapy for pancreatic cancer has been reported. Preoperative biliary drainage has become increasingly necessary, making the choice of stent an important one; thus, the longer the waiting period extends through neoadjuvant chemotherapy, the more durable stents - such as self-expandable metallic stents, rather than plastic stents - would be desired as an option. Still, there is insufficient evidence regarding surgical outcomes and long-term prognosis, and further confirmatory studies are needed. Through this review, we aim to provide an update on the characteristics of biliary stents and preoperative biliary drainage for potentially resectable pancreatic cancer.

Mechanical properties and degradation process of biliary self-expandable biodegradable stents

OBJECTIVES

The clinical outcomes and prevalence of adverse events associated with biliary biodegradable stents (BS) can differ according to degradation process and time. The aim of this study was to observe the degradation process and time of different BS prototypes, and to evaluate sequential changes in their mechanical properties.

METHODS

Using an in vitro bile flow phantom model, we compared degradation time, radial force changes, and morphologic changes among four different BS prototypes: polydioxanone (PDO) BS, polyglycolide (PGA) BS, polydioxanone/poly-l-lactic acid (PDO/PLLA) sheath-core BS, and polydioxaone/magnesium (PDO/Mg) sheath-core BS. Using an in vivo swine bile duct dilation model, we performed a direct peroral cholangioscopy (DPOC) examination to observe the biodegradation process and related adverse events at regular intervals.

RESULTS

In the bile flow phantom model, the PGA BS and PDO/Mg BS prototypes showed rapid radial force reduction and morphological changes and complete degradation within six weeks. PDO/PLLA BS maintained high radial force and kept their original shape for longer than the PDO BS, up to 16 weeks. A total of 24 BS were inserted into the dilated bile ducts of 12 swine. In this animal model, DPOC examination revealed that PDO BS and PDO/PLLA BS maintained their original shapes for approximately 12 weeks, but PDO BS showed a greater degree of fragmentation and induced biliary stones and bile duct obstruction.

CONCLUSION

Our results showed that PDO/PLLA BS maintained their original shape and radial force for a relatively long time and minimized adverse events.

The Exploration of a Novel Biodegradable Drug-Eluting Biliary Stent: Preliminary Work

PURPOSE

To explore the degradation, drug release, and mechanical properties of drug-incorporated films made of different ratios of poly(lactic-co-glycolic acid) (PLGA) and different amounts of paclitaxel (PTX), which may serve as the material platform for the manufacturing of biodegradable drug-eluting biliary stents.

MATERIALS AND METHODS

PLGA of different lactic acid/glycolic acid ratios (50/50, 70/30, and 80/20) and 0%, 10, 20, and 30% weight by weight (w/w) PTX was mixed to make PLGA films, which were then cut into small pieces for further testing. Films were immersed in phosphate-buffered saline (pH 7.4) for a maximum of 11 weeks. Samples were taken randomly at Day 2, 4, 6, 8, 10, 12, 14, and weekly thereafter until Week 11 to test tensile strength, weight loss, pH value of the soaking solution, and drug release. The morphology of films was observed using scanning electron microscope (SEM).

RESULTS

At Week 10 of degradation, PLGA 80/20 still withstood a tensile strength of 9.7 newton (N), while PLGA 50/50 and 70/30 cracked spontaneously since Day 4. At Week 11, weight loss of PLGA 50/50, 70/30, and 80/20 was 95.15, 82.32, and 16.17%, respectively; and the lowest pH value of soaking solution was 1.87, 1.95, and 6.58, respectively. Drug release of 10, 20, and 30% PTX groups was 3.52-4.48%, 1.90-2.26%, and 1.44-2.06%, respectively. SEM proved smooth films before degradation; however, after the tensile strength was lost, cracks could be seen.

CONCLUSION

The degradation rate of PLGA can be controlled by altering lactic acid/glycolic acid ratio. Overall, PLGA 50/50 and 70/30 degrade significantly faster than 80/20. PLGA can serve as an effective drug carrier for PTX while being the stent strut, and PTX can be slowly released as PLGA degrades.

New biliary and pancreatic biodegradable stent placement: a single-center, prospective, pilot study (with video)

BACKGROUND AND AIMS

In recent years, the feasibility and safety of endoscopic placement of different biodegradable biliary stents have been investigated. New, helicoidally shaped, biliary and pancreatic biodegradable stents have been developed for endoscopic use. Stents are provided in different sizes and with 3 expected speeds of degradation: slow (11 weeks), medium (20 days), and fast (12 days). The aim of this study was to evaluate degradation time, technical outcomes, and safety of these stents.

METHODS

This was a single-center, prospective, pilot study (August 2018 to January 2019) of consecutive patients with indication for biliary or pancreatic plastic stent positioning during ERCP. The primary outcome was the evaluation of degradation time of the stents, which was controlled by abdominal radiograph. Secondary outcomes were the evaluation of specific stent-related technical features (loadability, pushability, and fluoroscopic visibility) as compared with commonly used plastic stents and adverse events (AEs).

RESULTS

Thirty-eight patients (11 women [28.9%]; median age, 68.05 ± 10.74 years) who received 53 biodegradable stents (34 [64.2%] biliary and 19 [35.8%] pancreatic stents) were enrolled in the study. Thirty-five (66%) slow-degrading stents, 6 (11.3%) medium-degrading stents, and 12 (22.6%) fast-degrading stents were used. At time 1, partial degradation of the stents was present in 48 cases (90.6%). Five stents (9.4%) prematurely migrated. At the subsequent time 2 evaluation, complete degradation occurred in 100% of cases. Stent loadability was defined as excellent in all cases. Pushability of the stent was scored as excellent in 48 cases (90.5%), good in 4 cases (7.5%), and fair in 1 case (1.9%). Fluoroscopic visualization was excellent in 11 cases (20.8%), good in 39 cases (73.6%), and fair in 3 (5.6%). Only 1 AE of mild post-ERCP pancreatitis occurred.

CONCLUSIONS

The results of our study suggest that the biodegradation of the new biliary and pancreatic stents is reliable and in line with expected times and technically successful in a variety of indications. Further randomized multicenter studies are required to validate our preliminary findings. (Clinical trial registration number: NCT03767166.).

Reactivity Study of a Biodegradable Polydioxanone Tracheal Stent in a Rabbit Model

INTRODUCTION

The objective of this study was to evaluate tracheal reactivity induced by a biodegradable polydioxanone tracheal stent.

MATERIALS AND METHODS

Twenty-two rabbits were divided into 3 groups assigned to different survival times (30, 60 and 90days post-implantation). A biodegradable stent was implanted in each animal, except for 1 of each group (negative control). Implantation was performed through a small tracheotomy under fluoroscopic control. CT and histopathological studies were scheduled at the end of survival times.

RESULTS

No animal died during the procedure or follow-up. The stent had disappeared in 100% of the cases at 90days, in 50% at 60days, and in none at 30days. CT studies revealed a greater tracheal wall thickness at 30days than at 60 and 90days (1.60±0.41mm in the central part of the stent versus 1.11±0.18 and 0.94±0.11; P=.007, respectively). No granulomas were observed on histopathology. Some degree of histological changes were noted at 30days, which had reduced at 60 and 90days. Differences were also found in both CT and histology between animals in which the stent was present and animals in which it had degraded.

CONCLUSIONS

Polydioxanone stents produce a mild reaction that reverts with tracheal degradation. The use of these biodegradable stents in benign tracheal disease is promising.

Absorbable stents for treatment of benign biliary strictures: long-term follow-up in the prospective Spanish registry

OBJECTIVES

Benign strictures of the bile duct may be difficult to treat endoscopically due to altered bowel anatomy. Furthermore, recurrence of stenosis and symptoms remains high. The aim of the Spanish Prospective Registry BiELLA study was to investigate the safety and efficacy of absorbable stents in the treatment of benign biliary strictures and their outcomes on the medium and long-term follow-up.

METHODS

A prospective, multicenter, observational, non-randomized study (the BiELLA study) was conducted from January 2014 to September 2018. One hundred fifty-nine patients with benign biliary strictures, mostly postsurgical, were enrolled for implantation of absorbable biliary stents in the 11 participating Spanish tertiary hospitals. The average patient follow-up was 45.4 ± 15.9 months (range, 12-60 months). The follow-up data included symptoms, biochemical parameters, and ultrasound images at 1, 6, and 12 months and then yearly for up to 60 months.

RESULTS

The immediate technical and clinical success rates were 100%. In all patients, stent placement resulted in improvement of clinical symptoms and biochemical parameters. The primary mean patency for stent was 86.7, 79.6, and 78.9% at 12, 36, and 60 months, respectively (95% CI). Biliary restenosis and occlusion occurred in 40 (26.6%) patients. Of the 40 patients, 18 (12%) patients were treated with a second stent and 22 (14.6%) patients had operative repair of the recurrent strictures. There were no major complications associated with stent implantation.

CONCLUSIONS

Implantation of an absorbable polydioxanone biliary stent is safe and effective for treatment of benign biliary strictures refractory to balloon dilatation or other biliary intervention.

KEY POINTS

• Percutaneous implantation of biodegradable prostheses for the treatment of benign postsurgical biliary strictures is a safe and effective procedure. • More than 75% of the patients presented patency of the stented biliary tree at 5 years follow-up. • Absorbable stents improved clinical symptoms and signs (jaundice, itching, fever), and laboratory parameters in a few days after stent placement.

Endoscopic applications of magnets for the treatment of gastrointestinal diseases

Endoscopic treatment of gastrointestinal diseases has developed rapidly in recent years, due to its minimally invasive nature. One of the main contributing factors for this progress is the improvement of endoscopic instruments, which are essential for facilitating safe and effective endoscopic interventions. However, the slow learning curve required in the implementation of many advanced endoscopic procedures using standard devices is associated with a high risk of complications. Other routine procedures may also be complicated by unexpected difficulties. Based on the ferromagnetic properties of many objects, both internal and external magnetic devices have been developed and applied for multiple endoscopic interventions. The applications of magnets, mainly including compression, anchoring and traction, facilitate many difficult procedures and make it feasible to operate procedures that were previously impossible. Other novel endoscopic applications, such as magnetic nanoparticles, are also under development. In this article, we reviewed published studies of endoscopic applications of magnets for the treatment of gastrointestinal diseases such as precancerous lesions and cancer, obstruction, stricture, congenital and acquired malformations, motility disorders, and ingestion of foreign bodies. Since several endoscopic applications of magnets may also be relevant to surgery, we included them in this review.

Biodegradable biliary stents preferable to plastic stent therapy in post-cholecystectomy bile leak and avoid second endoscopy

BACKGROUND

The treatment of post-cholecystectomy bile leak is endoscopic retrograde cholangiography (ERC) with plastic stent (PS) insertion combined with external drainage. Self-expanding biodegradable biliary stents (BDBS) have only recently become available.

AIM

The aim was to compare success rate, adverse events and costs of BDBS with PS in the treatment of post-cholecystectomy cystic duct leak Materials and methods: Patients recruited prospectively for treatment with BDBS during the period 2014-2017 were compared to a control group treated with PS in a non-randomized setting.

RESULTS

Altogether 32 patients (median age 68, range 33-88, 59% male) were treated for Strasberg A bile leak over a period of 3.5 years, accounting for 1.8% of all ERCs. Eight patients were treated with BDBS and 24 with PS. Treatment with BDBS was safe; rate of readmissions and 30-day adverse events were 13% in both groups. There was no statistical difference in the clinical success rate. All cases with laparoscopic lavation or re-ERC with stent exchange occurred in the PS group. Total drain output was lower in BDBS patients (330ml vs 83ml, p=.002). All PS patients required another endoscopy for stent removal, whereas all BDBS patients were spared repeated endoscopy.

CONCLUSION

Treatment of cystic duct leak with BDBS is highly successful and as safe as traditional treatment with PS. The most obvious benefit of BDBS is that it avoids stent removal. The lower drain output after ERC with a trend for fewer unplanned interventions may indicate more efficient leak resolution with the large bore BDBS.

Endoscopic retrograde cholangiopancreatography, lights and shadows: Handle with care

The role of endoscopic retrograde cholangiopancreatography (ERCP) has dramatically changed in the last years, mainly into that of a therapeutic procedure. The treatment of benign biliary disease, like “difficult” choledocolithiasis, with endoscopic papillary large balloon dilation combined with endoscopic sphinterotomy has proven an effective and safe technique. Moreover, safety in ERCP has improved as well, with the prevention of post-ERCP pancreatitis and patient-to-patient transmission of infections. The advent of self-expandable metal stenting has radically changed the management of biliopancreatic malignant strictures, while the role for therapy of benign strictures is still controversial. In addition, cholangioscopy (though the direct visualization of the biliopancreatic ductal system) has allowed for characterization of indeterminate biliary strictures and facilitated rescue therapy of large biliary stones deemed removable. Encouraging data from tissue ablation techniques, such as photodynamic therapy and radiofrequency ablation, need to be confirmed by large sample size clinical controlled trials. On the other hand, we have no drug-coated stents yet available to implant and evidence for the use of biodegradable stents is still weak. The competency and privileging of ERCP and endoscopic ultrasonography have been analyzed longer but the switch between the two procedures, at the same time, is becoming ordinary; as such, the endoscopist interested in this field should undergo parallel edification through training plans. Finally, the American Society for Gastrointestinal Endoscopy’s statement on non-anesthesiologist administration of propofol for gastrointestinal endoscopy is not actually endorsed by the European Society of Anaesthesiology, having many medical-legal implications in some European countries.

A systematic review of biodegradable biliary stents: promising biocompatibility without stent removal

Biodegradable self-expanding stents are an emerging alternative to standard biliary stents as the development of endoscopic insertion devices advances. The aim was to systematically review the existing literature on biodegradable biliary stents. In-vivo studies on the use of biodegradable stents in the biliary duct were systematically reviewed from 1990 to 2017. Despite extensive research on the biocompatibility of stents, the experience so far on their clinical use is limited. A few favorable reports have recently been presented on endoscopically and percutaneously inserted self-expanding biodegradable polydioxanone stents in benign biliary strictures. Another potential indication appears to be postcholecystectomy leak of the cystic duct. The main benefit of biodegradable stents is that stent removal can be avoided. The biocompatibility of the current biodegradable stent materials, most prominently polydioxanone, is well documented. In the few studies currently available, biodegradable stents are reported to be feasible and safe, also in humans. The initial results of the endoscopic use of these stents in benign biliary stricture management and for treating postcholecystectomy bile leaks are promising. Further controlled studies on long-term clinical results and cost-effectiveness are needed.