Drug-eluting/biodegradable stents

Technical Review on Endoscopic Treatment Devices for Management of Upper Gastrointestinal Postsurgical Leaks

Upper gastrointestinal postsurgical leaks are challenging to manage and often require radiological, endoscopic, or surgical intervention. Nowadays, endoscopy is considered the first-line approach for their management, however, there is no definite consensus on the most appropriate therapeutic approach. There is a wide diversity of endoscopic options, from close-cover-divert approaches to active or passive internal drainage approaches. Theoretically, all these options can be used alone or with a multimodality approach, as each of them has different mechanisms of action. The approach to postsurgical leaks should always be tailored to each patient, taking into account the several variables that may influence the final outcome. In this review, we discuss the important developments in endoscopic devices for the treatment of postsurgical leaks. Our discussion specifically focuses on principles and mechanism of action, advantages and disadvantages of each technique, indications, clinical success, and adverse events. An algorithm for endoscopic approach is proposed.

Current status in endoscopic management of upper gastrointestinal perforations, leaks and fistulas

Recent advancement in endoscopic closure techniques have revolutionized the treatment of gastrointestinal perforations, leaks and fistulas. Traditionally, these have been managed surgically. The treatment strategy depends on the size and location of the defect, degree of contamination, presence of healthy surrounding tissues, patients' condition and the availability of expertise. One of the basic principles of management includes providing a barricade to the flow of luminal contents across the defect. This can be achieved with a wide range of endoscopic techniques. These include endoclips, stenting, suturing, tissue adhesives and glue, and endoscopic vacuum therapy. Each method has their distinct indications and shortcomings. Often, a combination of these techniques is required. Apart from endoscopic closure, drainage procedures by the interventional radiologist and surgical management also play an important role. In this review article, the outcomes of each of these endoscopic closure techniques in the literature is provided in tables, and practical management algorithms are being proposed.

From in vitro evaluation to human postmortem pre-validation of a radiopaque and resorbable internal biliary stent for liver transplantation applications

The implantation of an internal biliary stent (IBS) during liver transplantation has recently been shown to reduce biliary complications. To avoid a potentially morbid ablation procedure, we developed a resorbable and radiopaque internal biliary stent (RIBS). We studied the mechanical and radiological properties of RIBS upon in vivo implantation in rats and we evaluated RIBS implantability in human anatomical specimens. For this purpose, a blend of PLA₅₀-PEG-PLA₅₀ triblock copolymer, used as a polymer matrix, and of X-ray-visible triiodobenzoate-poly(ε-caprolactone) copolymer (PCL-TIB), as a radiopaque additive, was used to design X-ray-visible RIBS. Samples were implanted in the peritoneal cavity of rats. The radiological, chemical, and biomechanical properties were evaluated during degradation. Further histological studies were carried out to evaluate the degradation and compatibility of the RIBS. A human cadaver implantability study was also performed. The in vivo results revealed a decline in the RIBS mechanical properties within 3 months, whereas clear and stable X-ray visualization of the RIBS was possible for up to 6 months. Histological analyses confirmed compatibility and resorption of the RIBS, with a limited inflammatory response. The RIBS could be successfully implanted in human anatomic specimens. The results reported in this study will allow the development of trackable and degradable IBS to reduce biliary complications after liver transplantation. STATEMENT OF SIGNIFICANCE: Biliary reconstruction during liver transplantation is an important source of postoperative morbidity and mortality although it is generally considered as an easy step of a difficult surgery. In this frame, internal biliary stent (IBS) implantation is beneficial to reduce biliary anastomosis complications (leakage, stricture). However, current IBS are made of non-degradable silicone elastomeric materials, which leads to an additional ablation procedure involving potential complications and additional costs. The present study provides in vitro and human postmortem implantation data related to the development and evaluation of a resorbable and radiopaque internal biliary stent (RIBS) that could tackle these drawbacks.

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 stenting in colorectal cancer

Acute malignant large bowel obstruction presents as one of the few emergencies of colorectal cancer (CRC). Management of this condition can either be by (I) upfront surgery or (II) the use of self-expanding metallic stent (SEMS) as a bridge to elective surgery. For patients with metastasis, the use of SEMS is reported to enable earlier commencement of chemotherapy. Although the use of SEMS in patients with acute malignant large bowel obstruction looks promising, it is plagued by its own set of complications and divided opinion over its long-term outcomes. Conflicting data are present, and definitive indication requires further evaluation and debate. This article will describe the typical presentation of patients with acute malignant large bowel obstruction. An introduction to the SEMS insertion procedural steps will be undertaken. Following which the article aims to review the safety profile of SEMS and the short- and long-term outcomes of SEMS in both the curative and palliative setting.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

Efficacy and risk profile of self-expandable stents in the management of pediatric esophageal pathology

PURPOSE

The purpose of this study was to evaluate the efficacy and risk profile of esophageal stents in the management of complicated pediatric esophageal disease.

METHODS

An IRB-approved, single-center, retrospective review was performed on all pediatric patients (n = 13) who underwent esophageal stent placement (2005-2017). Demographic, perioperative, and outcome data were analyzed (p < 0.05).

RESULTS

Forty-one stents were placed due to recalcitrant strictures (n = 36), perforations (n = 2), and/or fistulae (n = 3). Median age at initial stent placement was 23.8 months (range, 50 days to 16 years), and median stent duration was 36 days (range, 3-335). The recurrence rate for strictures after initial stent removal was 100%. Four (31%) children subsequently underwent definitive operative repair. There were 5 deaths, including 2 related to stent placement. Seventy-one percent of stents were associated with an adverse event, most commonly intraluminal migration (56%). Younger children experienced an increased risk for airway compression and retching (p = 0.010).

CONCLUSION

These data suggest that stents are associated with high complication rates and are not effective as definitive therapy for recalcitrant strictures in children. Although there may be a temporizing role for stents in selected patients, further refinements in stent technologies are needed to help manage this difficult patient population.

LEVEL OF EVIDENCE

Level IV.

A Review of Self-Expanding Esophageal Stents for the Palliation Therapy of Inoperable Esophageal Malignancies

Esophageal cancer is a very deadly disease, killing more than 15,000 people in the United States annually. Almost 400,000 new cases happen in the worldwide every year. More than 50% esophageal cancer patients are diagnosed at an advanced stage when they need an esophageal stent to open the blocked esophagus for feeding and drinking. Esophageal stents have evolved in stages over the years. Current clinically used stents commonly include stainless steel or nitinol self-expandable metallic stent (SEMS) and self-expandable plastic stent (SEPS). There are many choices of different types of stents and sizes, with fierce competition among manufacturers. However, current stent technology, whether uncovered, partially covered, fully covered SEMS or SEPS, has their own advantages to solve the dysphagia, stricture, and fistula problems, but they also cause some clinical complications. The ideal stent remains elusive. New 3D printing technique may bring new promising potential to manufacturing personalized esophageal stents. Drug-eluting stents could be the new avenue to do more than just pry open a stricture or cover a defect in the esophageal lumen, a possibility of proving local anticancer therapy simultaneously. Additionally, the lack of esophageal cancer animal models also hinders the progress of stent development. This paper reviews these topics for a comprehensive understanding of this field. In a conclusion, the ultimate goal of the future esophageal stent would have multifunction to treat the underlying conditions and restore esophageal function to near normal.

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.

Endoscopic Closure of Gastrointestinal Fistulae and Leaks

The development of new endoscopic techniques, such as gastrointestinal (GI) stenting, full-thickness suturing, clip application, and use of tissue adhesives, has had a significant impact on management of GI fistulae. These techniques have shown promising results, but further study is needed to optimize the efficacy of long-term closure. The advancement of endoscopic techniques, including the use of the lumen apposing metal stent (LAMS), has allowed for the deliberate creation of fistula tracts to apply endoscopic therapy that previously could not be achieved. This article examines the rapidly evolving area of endoscopic fistula closure and its relationship to LAMS.

Surface modification of esophageal stent materials by a polyethylenimine layer aiming at anti-cancer function

Esophageal cancer is difficult to cure globally and possesses high mortality rate, and it is generally accepted that palliative care such as stent implantation is the main therapy method for esophageal cancer in later period. However, the restenosis caused by tumor cells and inflammatory cells seriously interferes the stent clinical application and limits its long-term services. To solve this problem, series of drug delivery stents were developed and proven rather effective in the early stage of implantation, but more serious restenosis occurred after the drug delivery was over, which endangered the patients' life. Therefore, endowing the esophageal stent continuous anti-cancer function become an ideal strategy for inhibiting the restenosis. In this contribution, the functional layer composed of polydopamine (PDA) and Poly-ethylenimine (PEI) with series of molecular weights (MW, 1.8 × 10³, 1 × 10⁴, 2.5 × 10⁴ and 7 × 10⁴ Da) were fabricated onto the esophageal stent material 317L stainless steel (317L SS) surface. The surface characterization including amine quantitative, atomic force microscopy (AFM) and water contact angle measurement indicated successful preparation of the PDA/PEI layer. The Eca109 cells culture results proved that the PDA/PEI layers significantly improve Eca109 cells apoptosis and necrosis, suggesting excellent anti-cancer function. In addition, we also found that the anti-cancer function of the PDA/PEI layers was positively correlated to the immobilized PEIs' MW. All the results demonstrated the potential application of the PDA/PEI layers on the surface modification of esophageal stent for continuous anti-cancer function. It is generally accepted that the restenosis caused by tumor cells seriously interferes the esophageal stent clinical application. Thus, endowing the esophageal stent continuous anti-cancer function is the ideal strategy for inhibiting the restenosis. In this work, we fabricated functional layers composed of polydopamine (PDA) and Poly-ethylenimine (PEI) with series of molecular weights (MW, 1.8 × 10³, 1 × 10⁴, 2.5 × 10⁴ and 7 × 10⁴ Da) onto the esophageal stent material 317L stainless steel (317L SS) surface to inhibit the tumor cells growth, and this function was related to the PEIs' molecular weights. The functional PDA/PEI layers were expected potentially applied for surface modification of esophageal stent materials.

Caustic ingestion

Corrosive ingestion is a rare but potentially devastating event and, despite the availability of effective preventive public health strategies, injuries continue to occur. Most clinicians have limited personal experience and rely on guidelines; however, uncertainty persists about best clinical practice. Ingestions range from mild cases with no injury to severe cases with full thickness necrosis of the oesophagus and stomach. CT scan is superior to traditional endoscopy for stratification of patients to emergency resection or observation. Oesophageal stricture is a common consequence of ingestion and newer stents show some promise; however, the place of endoscopic stenting for corrosive strictures is yet to be defined. We summarise the evidence to provide a plan for managing these potentially life-threatening injuries and discuss the areas where further research is required to improve outcomes.

Anastomotic Strictures after Esophageal Atresia Repair: Incidence, Investigations, and Management, Including Treatment of Refractory and Recurrent Strictures

Improved surgical techniques, as well as preoperative and postoperative care, have dramatically changed survival of children with esophageal atresia (EA) over the last decades. Nowadays, we are increasingly seeing EA patients experiencing significant short- and long-term gastrointestinal morbidities. Anastomotic stricture (AS) is the most common complication following operative repair. An esophageal stricture is defined as an intrinsic luminal narrowing in a clinically symptomatic patient, but no symptoms are sensitive or specific enough to diagnose an AS. This review aims to provide a comprehensive view of AS in EA children. Given the lack of evidence-based data, we critically analyzed significant studies on children and adults, including comments on benign strictures with other etiologies. Despite there is no consensus about the goal of the luminal diameter based on the patient's age, esophageal contrast study, and/or endoscopy are recommended to assess the degree of the narrowing. A high variability in incidence of ASs is reported in literature, depending on different definitions of AS and on a great number of pre-, intra-, and postoperative risk factor influencing the anastomosis outcome. The presence of a long gap between the two esophageal ends, with consequent anastomotic tension, is determinant for stricture formation and its response to treatment. The cornerstone of treatment is endoscopic dilation, whose primary aims are to achieve symptom relief, allow age-appropriate capacity for oral feeding, and reduce the risk of pulmonary aspiration. No clear advantage of either balloon or bougie dilator has been demonstrated; therefore, the choice is based on operator experience and comfort with the equipment. Retrospective evidences suggest that selective dilatations (performed only in symptomatic patients) results in significantly less number of dilatation sessions than routine dilations (performed to prevent symptoms) with equal long-term outcomes. The response to dilation treatment is variable, and some patients may experience recurrent and refractory ASs. Adjunctive treatments have been used, including local injection of steroids, topical application of mitomycin C, and esophageal stenting, but long-term studies are needed to prove their efficacy and safety. Stricture resection or esophageal replacement with an interposition graft remains options for AS refractory to conservative treatments.

Update on Enteral Stents

OPINION STATEMENT

The recent advances in enteral stents design and composition introduced novel usage and indications, heading to a continuous addition of prostheses application in clinical practice. Since the first use to palliate malignant diseases, improving patient's quality of life, in the last decades we assisted to a large spread, often becoming a first choice treatment in GI disorders. Indeed, the clinical indication of gastrointestinal stents includes endoscopic treatment of fistula and leaks besides the well-established role of restoring lumen patency in benign and malignant conditions. Several different kind of stents have been developed, each one with its own characteristics and benefits, including self-expandable plastic and metal stents, available as uncovered, partially covered, and fully covered as well as biodegradable stents. Recently, new drug-eluting stents, working both as palliative treatment and as local chemotherapy, are under evaluation. This review aims to critically evaluate the most recently published literature about enteral stents and to address endoscopists' choice for a better patient management.

Polymeric Biodegradable Stent Insertion in the Esophagus

Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. The partially covered self-expanding metal stent (SEMS) has a firm anchoring effect and prevent stent migration, however, the hyperplastic tissue reaction cause stent restenosis and make it difficult to remove. A fully covered SEMS and self-expanding plastic stent (SEPS) reduced reactive hyperplasia but has a high migration rate. The main advantage that polymeric biodegradable stents (BDSs) have over metal or plastic stents is that removal is not require and reduce the need for repeated stent insertion. But the slightly lower radial force of BDS may be its main shortcoming and a post-implant problem. Thus, strengthening support of BDS is a content of the research in the future. BDSs are often temporarily effective in esophageal stricture to relieve dysphagia. In the future, it can be expect that biodegradable drug-eluting stents (DES) will be available to treat benign esophageal stricture, perforations or leaks with additional use as palliative modalities for treating malignant esophageal stricture, as the bridge to surgery or to maintain luminal patency during neoadjuvant chemoradiation.

Endoscopic Management of Anastomotic Esophageal Strictures Secondary to Esophageal Atresia

The reported incidence of anastomotic stricture after esophageal atresia repair has varied in case series from as low as 9% to as high as 80%. The cornerstone of esophageal stricture treatment is dilation with either balloon or bougie. The goal of esophageal dilation is to increase the luminal diameter of the esophagus while also improving dysphagia symptoms. Once a stricture becomes refractory to esophageal dilation, there are several treatment therapies available as adjuncts to dilation therapy. These therapies include intralesional steroid injection, mitomycin C, esophageal stent placement, and endoscopic incisional therapy.

Biodegradable Airway Stents - Bench to Bedside: A Comprehensive Review

Airway stents are indicated to treat symptomatic narrowing or to close fistulas of the central airways. They are generally divided into two types: the silicone stents and the metallic stents. Unlike in malignancies, removability is a major objective of temporary stenting in benign conditions, which poses the challenge of a new rigid bronchoscopic procedure under general anesthesia and stent removal with all its attendant risks and costs. The concept of a biodegradable (BD) stent that could maintain the patency of an airway for a predetermined duration of time is very appealing. These BD stents would gradually degrade and eventually vanish from the airway once they are no longer needed. Such stents are currently an area of intense research. Another very promising concept of drug delivery with such stents is also a very exciting area of current research. The aim of this comprehensive review is to discuss all pertinent available literature on the use of BD materials in various clinical applications and to extensively review all animal and humans trials involving BD airway stents.

Biodegradable stents in gastrointestinal endoscopy

Biodegradable stents (BDSs) are an attractive option to avoid ongoing dilation or surgery in patients with benign stenoses of the small and large intestines. The experience with the currently the only BDS for endoscopic placement, made of Poly-dioxanone, have shown promising results. However some aspects should be improved as are the fact that BDSs lose their radial force over time due to the degradable material, and that can cause stent-induced mucosal or parenchymal injury. This complication rate and modest clinical efficacy has to be carefully considered in individual patients prior to placement of BDSs. Otherwise, the price of these stents therefore it is nowadays an important limitation.

Caustic injury of the upper gastrointestinal tract: A comprehensive review

Prevention has a paramount role in reducing the incidence of corrosive ingestion especially in children, yet this goal is far from being reached in developing countries, where such injuries are largely unreported and their true prevalence simply cannot be extrapolated from random articles or personal experience. The specific pathophysiologic mechanisms are becoming better understood and may have a role in the future management and prevention of long-term consequences, such as esophageal strictures. Whereas the mainstay of diagnosis is considered upper gastrointestinal endoscopy, computed tomography and ultrasound are gaining a more significant role, especially in addressing the need for emergency surgery, whose morbidity and mortality remains high even in the best hands. The need to perform emergency surgery has a persistent long-term negative impact both on survival and functional outcome. Medical or endoscopic prevention of stricture is debatable, yet esophageal stents, absorbable or not, show promising data. Dilatation is the first therapeutic option for strictures and bougies should be considered especially for long, multiple and tortuous narrowing. It is crucial to avoid malnutrition, especially in developing countries where management strategies are influenced by malnutrition and poor clinical conditions. Late reconstructive surgery, mainly using colon transposition, offers the best results in referral centers, either in children or adults, but such a difficult surgical procedure is often unavailable in developing countries. Possible late development of esophageal cancer, though probably overemphasized, entails careful and long-term endoscopic screening.

Pancreatic and biliary stents

Biliary and pancreatic stents are used in a variety of benign and malignant conditions including strictures and leaks and in the prevention of post-ERCP pancreatitis.Both plastic and metal stents are safe, effective, and easy to use. SEMSs have traditionally been used for inoperable malignant disease. Covered SEMSs are now being evaluated for use in benign disease. Increasing the duration of patency of both plastic and metal stents remains an important area for future research.