Antireflux biliary stents: are they the solution to stent occlusions?

Enteral extended biliary stents versus conventional plastic biliary stents for the treatment of extrahepatic malignant biliary obstruction: a single-center prospective randomized controlled study

BACKGROUND AND AIMS

The main limitation of plastic stents is the relatively short stent patency due to occlusion. We designed enteral extended biliary stents with lengths of 26 cm (EEBS-26 cm) and 30 cm (EEBS-30 cm) to prolong stent patency. This study aimed to compare patency among EEBS-26 cm, EEBS-30 cm, and conventional plastic biliary stent (CPBS).

METHODS

A single-center prospective randomized controlled study was conducted. Eligible patients were randomized into the EEBS-26 cm, EEBS-30 cm, and CPBS groups, respectively. All patients were followed up every 3 months until stent occlusion, patient death, or at 12-month follow-up. The primary outcome was stent patency. The secondary outcomes included stent occlusion rate, patient survival, mortality, the rate of technical success, and adverse events.

RESULTS

Totally 117 patients were randomized into the three groups. There were no significant differences among the three groups in technical success rate, hospital stay, mortality, patient survival, and adverse events (P = 1.000, 0.553, 0.965, 0.302, and 0.427, respectively). Median stent patency durations in the EEBS-26 cm, EEBS-30 cm, and CPBS groups were 156.0 (95% CI 81.6-230.4) days, 81.0 (95% CI 67.9-94.1) days, and 68.0 (95% CI 20.0-116.0) days, respectively (P = 0.002). The EEBS-26 cm group had longer stent patency compared with the CPBS (P = 0.007) and EEBS-30 cm (P < 0.001) groups. The EEBS-26 cm group had lower stent occlusion rates compared with the other groups at 6 months (48.1% vs. 90.5% vs. 82.8%, P = 0.001) and 9 months (75.0% vs. 100.0% vs. 92.9%, P = 0.022).

CONCLUSION

EEBS-26 cm has prolonged stent patency and is safe and effective for the alleviation of unresectable extrahepatic malignant biliary obstruction.

Usefulness of duckbill‐type anti‐reflux self‐expandable metal stents for distal malignant biliary obstruction with duodenal invasion: A pilot study

Objectives

Early obstruction of a self‐expandable metal stent placed for distal malignant biliary obstruction is more likely to occur in the presence of duodenal invasion. An anti‐reflux self‐expandable metal stent (ARMS) has been developed for the purpose of preventing duodenal fluid reflux into the bile duct. In this study, we evaluated the usefulness and safety of a duckbill‐type ARMS (D‐ARMS) in the situation of duodenal invasion.

Methods

We retrospectively analyzed 10 consecutive patients who received D‐ARMS for distal malignant biliary obstruction with duodenal invasion. We evaluated non‐occlusion cholangitis, recurrent biliary obstruction (RBO), and adverse events after D‐ARMS placement.

Results

There were no cases of non‐occlusion cholangitis. RBO was observed in 2 patients (20%), and time to RBO was 236 days and 117 days, respectively. The causes of RBO were overgrowth and sludge formation. The median time to RBO was 382 days (range, 117–382 days). Only one adverse event was observed (cholecystitis).

Conclusions

D‐ARMS shows potential as an optimal ARMS.

Design and Optimization of a New Anti-reflux Biliary Stent With Retractable Bionic Valve Based on Fluid-Structure Interaction Analysis

Duodenal biliary reflux has been a challenging common problem which could cause dreadful complications after biliary stent implantation. A novel anti-reflux biliary stent with a retractable bionic valve was proposed according to the concertina motion characteristics of annelids. A 2D equivalent fluid-structure interaction (FSI) model based on the axial section was established to analyze and evaluate the mechanical performances of the anti-reflux biliary stent. Based on this model, four key parameters (initial shear modulus of material, thickness, pitch, and width) were selected to investigate the influence of design parameters on anti-reflux performance via an orthogonal design to optimize the stent. The results of FSI analysis showed that the retrograde closure ratio of the retractable valve primarily depended on initial shear modulus of material (p < 0.05) but not mainly depended on the thickness, pitch, and width of the valve (p > 0.05). The optimal structure of the valve was finally proposed with a high retrograde closing ratio of 95.89%. The finite element model revealed that the optimized anti-reflux stent possessed improved radial mechanical performance and nearly equal flexibility compared with the ordinary stent without a valve. Both the FSI model and experimental measurement indicated that the newly designed stent had superior anti-reflux performance, effectively preventing the duodenobiliary reflux while enabling the bile to pass smoothly. In addition, the developed 2D equivalent FSI model provides tremendous significance for resolving the fluid-structure coupled problem of evolution solid with large deformation and markedly shortens the calculation time.

Antireflux metal stent for biliary obstruction: Any benefits?

Endoscopic retrograde cholangiopancreatography with stent placement has been utilized as standard palliative management of distal malignant biliary obstruction (MBO). Compared to plastic stents, metal stents can provide longer-term relief of symptoms. When a large-bore metal stent is placed across the ampulla, patients are predisposed to the risk of cholangitis or stent dysfunction due to reflux of duodenal contents. To mitigate the risk of adverse events associated with the duodenobiliary reflux, efforts have been directed to development of antireflux metal stents (ARMSs). The antireflux property has been introduced through adding of an antireflux valve to the duodenal stent end. Evidence from clinical studies indicates that ARMSs may not only reduce the risk of ascending cholangitis during follow-up but also prolong stent patency time. However, the results of clinical studies testing ARMSs are inconsistent owing to heterogeneous designs of antireflux valves and stent bodies. Metal stents are increasingly indicated for benign biliary strictures and MBO in the setting of neoadjuvant chemotherapy, and therefore, research is warranted to evaluate ARMSs for those indications. Given that endoscopic ultrasound (EUS)-guided transmural biliary drainage has gained popularity, the optimal timing of placing an ARMS in relation to EUS-guided and percutaneous drainage should be investigated. Development and evaluation of ARMSs require an integrative approach utilizing phantom and animal models, measurements of stent mechanical properties, and in vivo functional study after stent placement. In this review article, we summarize updated evidence on ARMSs for MBO and discuss issues that should be addressed in future studies.

Suspended over length biliary stents versus conventional plastic biliary stents for the treatment of biliary stricture: A retrospective single-center study

To compare patency between suspended over length biliary stents (SOBSs; made from nasobiliary tube) and conventional plastic biliary stents (CPBSs).We retrospectively analyzed 61 patients with extrahepatic biliary stricture who underwent SOBS placement (intrahepatic bile duct) and 74 patients who underwent CPBS placement. Stent patency and complications were compared.The SOBS group was slightly older and contained more females than the CPBS group but other baseline characteristics were similar. Malignant biliary obstruction accounted for 57.4% (SOBS group) and 45.9% (CPBS group) of cases. Technical success rate, hospital stay and post-procedure complications were similar between groups. Median patency in the CPBS and SOBS group was 116 (2-360) days and 175 (3-480) days, respectively (P <.001). The SOBS group had lower stent occlusion rates than the CPBS group at 3 months (9.8% vs 36.5%), 4 months (22.0% vs 55.4%), 5 months (35.6% vs 67.6%), and 6 months (39.3% vs 77.0%) (all P <.01). In Cox regression analysis, stent type (SOBS vs CPBS) was the only factor associated with patency (hazard ratio [HR]: 3.449; 95% CI: 1.973-6.028; P <.001).SOBS may have better medium-term patency than CPBS for benign/malignant biliary stricture.

Novel antireflux covered metal stent for recurrent occlusion of biliary metal stents: a pilot study

BACKGROUND

Feasibility of antireflux metal stent (ARMS), designed to prevent duodenobiliary reflux, was reported in patients with distal malignant biliary obstruction. In this prospective pilot study, we aimed to evaluate a newly designed ARMS as a reintervention for self-expandable metallic stent (SEMS) occlusion believed to be caused by duodenobiliary reflux.

PATIENTS AND METHODS

Patients with non-resectable distal malignant biliary obstruction were included in whom a prior SEMS was occluded as a result of sludge or food impaction between March 2010 and January 2012 at two Japanese tertiary referral centers. The occluded SEMS were endoscopically removed, if possible, and subsequently replaced by a newly designed ARMS. We evaluated the technical success rate and complications of ARMS and compared the time to occlusion of ARMS with that of prior SEMS.

RESULTS

A total of 13 patients were included. ARMS was successfully placed in all patients in a single procedure. No procedure-related complications were identified. ARMS occlusion occurred in two patients (15%), the causes of which were sludge in one patient and unknown in the other. ARMS migration occurred in four patients (31%). ARMS patency time was significantly longer than that of prior SEMS (median, not available vs 58 days; P = 0.039).

CONCLUSIONS

This newly designed ARMS is a technically feasible, safe, and effective reintervention for SEMS occlusion as a result of sludge or food impaction. An anti-migration mechanism to improve the outcomes of ARMS should be considered.

Does heparin coating reduce encrustation of biliary plastic endoprostheses? A prospective randomized trial

OBJECTIVE

Common bile duct stenting is widely performed for bridging benign and malignant obstructions. A major limitation is early stent occlusion making regular stent exchange necessary. Covalent binding of glycosaminoglycanes to polyethylene stents proved to reduce encrustation in urological implants. Since development of urological and biliary stent occlusion shows parallels, the aim of the study was to evaluate the efficacy of heparin coating of biliary endoprostheses in preventing encrustation.

MATERIAL AND METHODS

In a prospective randomized trial, heparin-coated and native stents were endoscopically placed for almost 90 days on average. After removal, all stents were dried (50°C, 24 h), weighed and after longitudinal incision visible encrustation and discoloration recorded. Fifty-three patients (21 females/32 males, 70 ± 12 (42-87) years) were included; 13 patients (4 females/9 males, 58-79 years) completed the study according to the protocol.

RESULTS

After removal, mean weight of encrustation in native stents was more than double as high as of covered stents (native: 37.9 ± 19.8 (16-93) mg; covered: 17.6 ± 6.7 (9-33) mg). In 12 of 13 cases, the encrustation weight of the native stent was higher than that of the corresponding covered stent in the same patient. Premature stent explantation became necessary in 3 of 13 native stents, because of recurrent jaundice or cholangitis but only in 1 of 13 covered stents. After longitudinal incision, the three uncovered stents showed excessive encrustation whereas no significant encrustation was found in the covered prosthesis. Altogether, covered stents showed less visible accumulation of clogging material and discoloration than native stents.

CONCLUSIONS

Covalent bound heparin is highly effective in preventing encrustation of biliary polyethylene endoprostheses.

Endoscopic management of benign biliary strictures

Endoscopic retrograde cholangiopancreatography (ERCP) is the first-line management in most situations when a benign biliary stricture is suspected. Although management principles are similar in all subgroups, the anticipated response rates, need for ancillary medical and endoscopic approaches, and use of less proven strategies vary between differing causes. Exclusion of malignancy should always be a focus of management. Newer endoscopic techniques such as endoscopic ultrasound, cholangioscopy, confocal endomicroscopy, and metal biliary stenting are increasingly complementing traditional ERCP techniques in achieving long-term sustained stricture resolution. Surgery remains a definitive management alternative when a prolonged trial of endoscopic therapy does not achieve treatment goals.

Repeat Procedures Within 30 days in Patients Stented for Malignant Distal Biliary Strictures: Experience of 508 Patients at a Tertiary Referral Center

Background

Stent related occlusion and migration remains a problem despite attempts to improve stent design over this time period. Flanged polyethylene plastic stents (FPS) remains the stent of choice in most centers. Early failure of stents placed for malignant extrahepatic biliary strictures (MEBS) has not previously been studied in detail. We set out to determine the incidence and reasons for biliary stent change within 30 days of the index procedure in a large tertiary center population during a period where (FPS) was the sole plastic stent used.

Methods

Retrospective analysis of endoscopic retrograde cholangiography (ERCP) was undertaken in patients who were stented for presumed or known MEBS between 1993 and 2001. Patients who required repeat stenting within 30 days were identified.

Results

All 508 patients were stented for MEBS. 5.7% of patients had a total of 34 repeat stenting procedures within 30 days of the index procedure; 27of 29 index stents were plastic, 2 were self-expandable metal stents (SEMS), 20 (3.9%) patients had stent failure as the reason for a stent exchange (plastic stent occlusion n = 15, mean time to stent change 14 ± 8.3 days; metal stent occlusion n = 2, mean time to stent change 24.5 ± 7.8 days; plastic stent migration n = 3, mean time to stent change 25 ± 5.3 days). There was a statistically significant difference in the time to stent change between the occluded plastic stent and migrated plastic stent cases (P = 0.045, 95% CI -21.7 to -0.29). 6 patients spent at least 2 additional days in hospital as a result of stent failure.

Conclusions

Early stent failure is an uncommon problem, especially in patients with SEMS. Early plastic stent failure appears to occur sooner with stent occlusion than with stent migration. Early stent failure is associated with significant morbidity and bears an economic impact in additional procedures and hospital stay.

Plastic biliary stents for malignant biliary diseases

Plastic biliary endoprostheses have not changed much since their introduction more than 3 decades ago. Although their use has been challenged by the introduction of metal stents, plastic stents still remain commonly used. Much work has been done to improve the problem of stent obstruction but without substantial clinical success. In this review, the authors discuss the history of plastic biliary stent development and the current use of plastic stents for malignant biliary diseases.

Endoscopic stenting for palliation of malignant biliary obstruction

Malignant biliary obstruction results in jaundice, often with symptoms that decrease the quality of life. Biliary stent placement has largely supplanted surgical bypass for palliation of malignant biliary obstruction. Traditional rigid plastic stents are commonly used, inexpensive and easily removed, although with limited duration of stent patency. Self-expandable metal stents (SEMS) attain larger luminal diameters and provide longer patency than traditional rigid plastic stents in patients with distal bile duct obstruction. SEMS are composed of a variety of metals and can be uncoated, partially covered, or fully covered. Data do not support a prolongation of patency with covered SEMS for distal obstruction, although they have the potential for removability. The data to support SEMS for palliation of hilar biliary obstruction are not as convincing and reintervention for stent occlusion can be difficult. In this article, the design and performance of expandable metal stents for treatment of malignant biliary obstruction will be reviewed.

Endoscopic palliation of malignant obstructive jaundice: an evidence-based review

Endoscopic stent insertion is considered the method of choice for palliative treatment of malignant biliary obstruction. Nonetheless, relevant studies are often underpowered or outdated and do not compare actual surgical outcomes with latest stent technology. Purpose of this review was to assess, with an evidence-based methodology, the role of endoscopic versus surgical palliation of patients with malignant obstructive jaundice with special reference to clinical effectiveness, safety aspects and economic outcomes.

Plastic biliary stent occlusion: factors involved and possible preventive approaches

Endoscopic biliary stenting is today the most common palliative treatment for patients suffering from obstructive jaundice associated with malignant hepatobiliary tumors or benign strictures. However, recurrent jaundice, with or without cholangitis, is a major complication of a biliary endoprosthesis insertion. Thus, stent removal and replacement with a new one frequently occurs as a consequence of device blockage caused by microbial biofilm growth and biliary sludge accumulation in the lumen. Factors and mechanisms involved in plastic stent clogging arising from epidemiological, clinical and experimental data, as well as the possible strategies to prevent biliary stent failure, will be reviewed and discussed.