Time Sequence Evaluation of Biliary Stent Occlusion by Dissection Analysis of Retrieved Stents

A microsystem for in vivo wireless monitoring of plastic biliary stents using magnetoelastic sensors

With an interest in monitoring the patency of stents that are used to treat strictures in the bile duct, this paper reports the investigation of a wireless sensing system to interrogate a microsensor integrated into the stent. The microsensor is comprised of a 28-μm-thick magnetoelastic foil with 8.25-mm length and 1-mm width. Magnetic biasing is provided by permanent magnets attached to the foil. These elements are incorporated into a customized 3D polymeric package. The system electromagnetically excites the magnetoelastic resonant sensor and measures the resulting signal. Through shifts in resonant frequency and quality factor, the sensor is intended to provide an early indication of sludge accumulation in the stent. This work focuses on challenges associated with sensor miniaturization and placement, wireless range, drive signal feedthrough, and clinical use. A swine specimen in vivo experiment is described. Following endoscopic implantation of the sensor enabled plastic stent into the bile duct, at a range of approximately 17 cm, the signal-to-noise ratio of ~106 was observed with an interrogation time of 336 s. These are the first reported signals from a passive wireless magnetoelastic sensor implanted in a live animal.

Pilot study on cultural and metagenomic analysis of bile and biliary stentslead to unveiling the key players in stent occlusion

Endoscopic Retrograde Cholangio-Pancreatography (ERCP) with biliary stenting is a minimally invasive medical procedure employed to address both malignant and benign obstructions within the biliary tract. Benign biliary strictures (BBSs), typically arising from surgical interventions such as liver transplants and cholecystectomy, as well as chronic inflammatory conditions, present a common clinical challenge. The current gold standard for treating BBSs involves the periodic insertion of plastic stents at intervals of 3-4 months, spanning a course of approximately one year. Unfortunately, stent occlusion emerges as a prevalent issue within this treatment paradigm, leading to the recurrence of symptoms and necessitating repeated ERCPs. In response to this clinical concern, we initiated a pilot study, delving into the microbial composition present in bile and on the inner surfaces of plastic stents. This investigation encompassed 22 patients afflicted by BBSs who had previously undergone ERCP with plastic stent placement. Our preliminary findings offered promising insights into the microbial culprits behind stent occlusion, with Enterobacter and Lactobacillus spp. standing out as prominent bacterial species known for their biofilm-forming tendencies on stent surfaces. These revelations hold promise for potential interventions, including targeted antimicrobial therapies aimed at curtailing bacterial growth on stents and the development of advanced stent materials boasting anti-biofilm properties.

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.

New anti-reflux plastic stent to reduce the risk of stent-related cholangitis in the treatment of biliary strictures

BACKGROUND

There is little data available on the role of new anti-reflux plastic stents (ARPSs).

AIM

To compare the use of ARPSs with that of traditional plastic stents (TPSs) for patients with biliary strictures.

METHODS

Consecutive patients with biliary strictures who underwent first endoscopic biliary stenting between February 2016 and May 2019 were included. The onset of stent-related cholangitis, stent patency, clinical success, and other adverse events were evaluated.

RESULTS

Sixty-seven patients in the ARPS group and 66 patients in the TPS group were included in the final analyses. Fewer patients experienced stent-related cholangitis in the ARPS group than that in the TPS group (8 patients vs 18 patients; P = 0.030). The median time till the onset of first stent-related cholangitis was later in the ARPS group than that in the TPS group (128.5 d vs 76 d; P = 0.039). The cumulative median stent patency in the ARPS group was 185 d, which was significantly longer than that in the TPS group (133 d; P = 0.001). The clinical success rates and other adverse events did not significantly differ between both groups.

CONCLUSION

Placement of new ARPS might be a safe and effective optional therapeutic strategy to reduce the risk of stent-related cholangitis and prolong stent patency.

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.

What is the better surgical treatment option for recurrent common bile duct stones?

Purpose

Repeating endoscopic retrograde cholangiopancreatography (ERCP) in patients with recurrent common bile duct (CBD) stones is problematic in many ways. Choledochoduodenostomy (CDS) and choledochojejunostomy (CJS) are 2 surgical treatment options for recurrent CBD stones, and each has different advantages and disadvantages. The aim of this study was to compare the 2 surgical options in terms of the recurrence rate of CBD stones after surgical treatment.

Methods

This retrospective multicenter study included all patients who underwent surgical treatment due to recurrent CBD stones that were not effectively controlled by medical treatment and repeated ERCP between January 2006 and March 2015. We collected data from chart reviews and medical records. A recurrent CBD stone was defined as a stone found 6 months after the complete removal of a CBD stone by ERCP. Patients who underwent surgery for other reasons were excluded.

Results

A total of 27 patients were enrolled in this study. Six patients underwent CDS, and 21 patients underwent CJS for the rescue treatment of recurrent CBD stones. The median follow-up duration was 290 (180–1,975) days in the CDS group and 1,474 (180–6,560) days in the CJS group (P = 0.065). The postoperative complications were similar and tolerable in both groups (intestinal obstruction; 2 of 27, 7.4%; 1 in each group). CBD stones recurred in 4 patients after CDS (4 of 6, 66.7%), and 3 patients after CJS (3 of 21, 14.3%) (P = 0.010).

Conclusion

CJS may be a better surgical option than CDS for preventing further stone recurrence in patients with recurrent CBD stones.

[Mechanisms and prevention of biliary stent occlusion]

One of significant achievements of modern endoscopy is development of retrograde biliary stenting for obstructive jaundice. This method ensured widespread application of endoscopic decompression in the treatment of patients with malignant biliary obstruction as preparation before radical surgery and final palliative care. Endoscopic retrograde transpapillary stenting firmly took its place together with antegrade and percutaneous stenting. There are certain advantages of this technique including minimally invasiveness and favorable quality of life. However, this approach is associated with some drawbacks associated with stent occlusion and difficult correction of this complication. The maximum diameter of the plastic stent (PS) is determined by the width of the working channel of the duodenoscope. In this regard, self-expandable metal stents (SEMS) were developed to increase the diameter of bile drainage channel. SEMS are associated with prolonged function. However, there is another problem. It is a germination of SEMS followed by impossible removal of the stent for its subsequent replacement. A further step in development of endoscopic biliary stents was the use of special SEMS coating to exclude tumor or granulation ingrowth. The problem of biliary stent occlusion remains relevant despite some improvement of stenting results. Mechanisms of occlusion of biliary stents and prevention of these events are discussed in this review.

[Relief of Obstruction in the Management of Pancreatic Cancer]

Pancreatic cancer is a major cause of cancer-related mortality and morbidity, and its incidence is increasing as the population is aging. On the other hand, significant improvement in the prognosis has not occurred. The absence of early diagnosis means that many patients are diagnosed only when they develop symptoms, such as jaundice, due to a biliary obstruction. The role of endoscopy in multidisciplinary care for patients with pancreatic cancer continues to evolve. Controversy remains regarding the best preoperative biliary drainage in patients with surgically resectable pancreatic head cancer. In general, patients undergoing a surgical resection usually do not require preoperative biliary drainage unless they have cholangitis or receive neoadjuvant chemotherapy. If biliary drainage is performed prior to surgery, the patient's condition and a multidisciplinary approach should be considered. With the increasing life expectancy of patients with pancreatic cancer, the need for more long-time biliary drainage or pre-operative biliary drainage is also increasing. Strong evidence of endoscopic retrograde cholangiopancreatography (ERCP) as a first-line and essential treatment for biliary decompression has been provided. On the other hand, the use of endoscopic ultrasound-guided biliary drainage as well as percutaneous biliary drainage has been also recommended. During ERCP, self-expandable metal stent could be recommended instead of a plastic stent for the purpose of long stent patency and minimizing stent-induced complications. In this review, several points of view regarding the relief of obstruction in patients with pancreatic cancer, and optimal techniques are being discussed.

New antireflux plastic stent for patients with distal malignant biliary obstruction

BACKGROUND

Endoscopic biliary stenting is a well-established palliative treatment for patients with unresectable distal malignant biliary obstruction (MBO). However, the main problem with stent placement is the relatively short duration of stent patency. Although self-expanding metal stents (SEMSs) have a longer patency period than plastic stents (PSs), the higher costs limit the wide use of SEMSs. A PS with an antireflux valve is an attractive idea to prolong stent patency, but no ideal design for an antireflux PS (ARPS) has been proposed. We developed a new ARPS with a "duckbilled" valve attached to the duodenal end of the stent.

AIM

To compare the patency of ARPSs with that of traditional PSs (TPSs) in patients with unresectable distal MBO.

METHODS

We conducted a single-center, prospective, randomized, controlled, double-blind study. This study was conducted at the West China Hospital of Sichuan University. Consecutive patients with extrahepatic MBO were enrolled prospectively. Eligible patients were randomly assigned to receive either an ARPS or a TPS. Patients were followed by clinic visits or telephone interviews every 1-2 mo until stent exchange, death, or the final study follow-up in October 2018. The primary outcome was the duration of stent patency. Secondary outcomes included the rate of technical success, the rate of clinical success, adverse events, and patient survival.

RESULTS

Between February 2016 and December 2017, 38 patients were randomly assigned to two groups, with 19 patients in each group, to receive ARPSs or TPSs. Stent insertion was technically successful in all patients. There were no significant differences between the two groups in the rates of clinical success or the rates of early or late adverse events (P = 0.660, 1.000, and 1.000, respectively). The median duration of stent patency in the ARPS group was 285 d [interquartile range (IQR), 170], which was significantly longer than that in the TPS group (median, 130 d; IQR, 90, P = 0.005). No significant difference in patient survival was noted between the two groups (P = 0.900).

CONCLUSION

The new ARPS is safe and effective for the palliation of unresectable distal MBO, and has a significantly longer stent patency than a TPS.

Accelerated in vitro model for occlusion of biliary stents: investigating the role played by dietary fibre

Background

To develop a new accelerated in vitro model that has implications for investigating the mechanism of biliary stent occlusion and help in the development of new materials that can alleviate this problem.

Methods

We employ a combination of reconstituted animal bile, bacteria and cellulose fibres optimised to reproducibly generate accelerated occlusion of stents, and produce occlusions that closely mimic those found in clinical studies.

Results

Our model affords repeatable, highly accelerated occlusion (within 2–3 days, compared with between about a week to 2 months in previous models). Our results highlight the role of dietary fibre in blockage of stents and demonstrate their importance in the onset of occlusion.

Conclusions

This accelerated model may have implications for developing biliary stents with enhanced patency.

Predictive risk factors associated with cholangitis following ERCP

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) with stent placement is used for the management of many pancreaticobiliary disorders. It is generally safe with a few short-term complications. The risk factors for the development of post-ERCP cholangitis due to stent occlusion have not been previously described. This study identified such risk factors among patients undergoing ERCP and stent placement for pancreatic or biliary obstruction.

METHODS

3648 ERCPs performed at the University of Louisville from 2008 to 2016 were reviewed. Data including patient demographics, diagnostic, laboratory, and ERCP related data were included. Patients were classified as having post-ERCP cholangitis if they developed jaundice, fever, right upper quadrant abdominal pain, and confirmatory findings of stent occlusion and/or purulent drainage at the time of repeat ERCP. These patients were compared to those who did not develop post-ERCP cholangitis using univariate and multivariate analyses.

RESULTS

A total of 431 patients met inclusion criteria. Of these, 57 (13.2%) developed post-ERCP cholangitis. The average age of patients was 57 years with 57% women and 43% men. On univariate analysis, patients developing post-ERCP cholangitis were more likely to be of increased age, have higher white blood cell count (WBC), total bilirubin (TBili), AST, ALT, and alkaline phosphatase (AlkPhos), and a decreased serum albumin level. Risk factors for post-ERCP cholangitis due to stent occlusion identified on multivariate analysis include: a diagnosis of cancer, the placement of multiple biliary stents at index ERCP, and low serum albumin level.

CONCLUSIONS

The development of post-ERCP cholangitis due to stent occlusion is strongly associated with the presence of malignancy, the placement of multiple biliary stents, and low serum albumin. A decreased threshold to monitor for stent occlusion, including routine liver function tests and prophylactic stent removal or exchange, should be employed in patients with these characteristics.

The Stent Patency and Migration Rate of Different Shaped Plastic Stents in Bile Flow Phantom Model and In Vivo Animal Bile Duct Dilation Model

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.