Biomechanical Study of New Biodegradable Esophageal Stent / 中国医疗器械杂志

The radial force of the degradable esophageal stent before and after degradation is one of the important indicators for effective treatment of esophageal stricture. Based on a combination of in vitro experiments and finite element analysis, this paper studies and verifies the biomechanical properties of a new type of degradable esophageal stent under different esophageal stricture conditions. Under radial extrusion conditions, the maximum stress at the port of the stent is 65.25 MPa, and the maximum strain is 1.98%; The peak values of stress and strain under local extrusion and plane extrusion conditions both appear in the extrusion area and the compression expansion area at both ends, which are respectively 48.68 MPa, 46.40 MPa, 0.49%, 1.13%. The maximum radial force of the undegraded stent was 11.22 N, and 97% and 51% of the maximum radial force were maintained after 3 months and 6 months of degradation, respectively. The research results verify the safety and effectiveness of the radial force of the new degradable esophageal stent, and provide a theoretical basis for the clinical treatment of esophageal stricture.

Research Progress in Fatigue Properties of Esophageal Stent / 医用生物力学

Due to the effect of structural characteristics and service environment of esophageal stent, fatigue damage of esophageal stent is developed easily, which may lead to serious complications. At present, the researches on fatigue performance of esophageal stent involve load spectrum, stress-strain relationship, fatigue crack and fatigue life prediction, and there are three main research method: theoretical analysis, numerical simulation and experimental research. In this paper, various analysis methods and limitations for measuring fatigue performance of esophageal stent are elaborated and summarized in detail, and the future research of esophageal stent is prospected.

Esophageal stent placement versus endoscopic incision for the treatment of refractory esophageal anastomotic stricture / 医学研究生学报

Objective Few reports are seen comparing esophageal stent placement (ESP) and the endoscopic incision method (EIM) in the treatment refractory esophageal anastomotic strictures (EAS) following esophageal carcinoma resection (ECR). This study was to evaluate the effect ESP versus that of EIM in the treatment of refractory EAS after ECR. Methods We retrospectively analyzed the clinical data on 50 cases of post-ECR refractory EAS treated by ESP (n = 32) or EIM (n = 18) in our Center of Digestive Medicine between January 2012 and December 2018. We recorded and compared the pre- and post-operative dysphagia scores, post-operative complications and follow-up results between the two groups of patients. Results Compared with the EIM group, the patients of the ESP group had a remarkably lower dysphagia score post-operatively (1.4±0.5 vs 1.0±0.0, P<0.01), a smaller diameter of the dilated esophagus ([19.9±1.8] vs [11.0±1.9] mm, P<0.01), higher incidence rates mild and severe chest pain (P=0.022), and a higher rate of relief of esophageal stricture at 12 months after surgery (P<0.05). Conclusion EIM can rapidly relieve the symptoms of esophageal anastomotic stricture, while ESP may achieve a longer duration of relief. Both of the procedures are safe for patients with refractory esophageal anastomotic stricture.

Research progress on esophageal stents for children / 上海交通大学学报（医学版）

Currently, benign esophageal stricture is a common clinical esophageal disease in children, and its common treatment is balloon dilatation. According to the complexity of the lesion, the child often suffers from multiple esophageal dilation. Besides, esophageal stent provides a new choice for the treatment of esophageal stricture in children because of the long-lasting support. However, the complications limit its clinical application, such as chest pain, restenosis, and stent displacement. This article reviewed the current research and clinical application of esophageal stents for children.

Advance in research of esophageal stent / 中国胸心血管外科临床杂志

@#The esophageal disease is a major clinical disease. The esophageal stent has extensive clinical applications in the treatment of esophageal diseases. However, the clinical application of esophageal stent is limited, because there are lots of complications after implantation of esophageal stent. Biodegradable esophageal stent has two advantages: biodegradability and good histocompatibility. It is expected to solve a variety of complications of esophageal stent and provide a new choice for the treatment of esophageal diseases. Standardized esophageal stents are not fully applicable to all patients. The application of 3D printing technology in the manufacture of biodegradable esophageal stent can realize the individualized treatment of esophageal stent. And meanwhile, the 3D printing technology can reduce the manufacturing cost of the stent. This review aimed to summarize and discuss the application of esophageal stent, the current research status and prospect of biodegradable esophageal stent and the prospect of 3D printing technology in degradable esophageal stent, hoping to provide evidence and perspectives for the research of biodegradable esophageal stent.

The establishment of esophageal re-stenosis model by using esophageal stent implantation: observation in experimental rats / 介入放射学杂志

Objective To evaluate the feasibility and safety of establishing benign proliferative esophageal stenosis model by using stent implantation in experimental rats.Methods A customized self-expanding,metallic and straight tubular stent was used in this experiment (5 mm in diameter and 15 mm in length),on both sides at the stent's middle part there was a protruding barb that was used as a fixation device.Twelve healthy Sprague Dawley (SD) rats were randomized divided into group A (blank control group) and group B (stent implantation group),with 6 rats in each group.Esophageal stent implantation was employed in the rats of group B,and esophageal radiography was separately performed immediately,one and 4 weeks after stent implantation.All the experimental rats were sacrificed 4 weeks after stent implantation.The normal esophageal tissue of the rats in group A and the esophageal tissue at stent site of the rats in group B were collected and sent for pathological examinations,including gross morphology,light microscopy,etc.Results Successful stent implantation was achieved in all rats of group B,and the esophageal radiography performed immediately,one and 4 weeks after stent implantation showed no esophageal stent displacement;no severe complications occurred during the operation or follow-up period.Compared with group A,esophageal radiography reexamination performed 4 weeks after stent implantation in group B revealed that esophageal stricture at stent segment,caused by benign tissue hyperplasia,could be observed.The esophageal stent segment was taken out,its lumen was obviously narrowed under gross observation,and typical benign hyperplasia could be seen under optical microscope examination.Conclusion Using esophageal stent implantation to establish esophageal stenosis model is safe and feasible in experimental rats.The use of esophageal stent with barbs can significantly reduce the incidence of stent displacement.

Factors That Affect Stent-Related Complications in Patients with Malignant Obstruction of the Esophagus or Gastric Cardia

BACKGROUND/AIMS: Self-expandable metallic stent (SEMS) placement is effective for dysphagia that results from malignant obstruction of the esophagus or gastric cardia; however, stent-related complications may be life-threatening. Thus, the goal of this study was to identify risk factors associated with complications following esophageal stenting. METHODS: Of the 71 patients who underwent SEMS placement for dysphagia as a result of malignant stricture of the esophagus or gastric cardia, 53 patients with squamous cell carcinoma or adenocarcinoma, without previous SEMS placement, without a fistula, and without recurrent tumor after surgery were retrospectively identified. The occurrence of stent-related complications was used as an endpoint. RESULTS: Stent-related complications were identified in 26 patients (49.1%), and major complications occurred in 14 patients (26.4%). The use of an Ultraflex stent (odds ratio [OR], 6.81; 95% confidence interval [CI], 1.54 to 30.00; p=0.011) and prior chemotherapy (OR, 6.13; 95% CI, 1.46 to 25.70; p=0.013) were significantly associated with stent-related complications. Moreover, the use of an Ultraflex stent (OR, 19.60; 95% CI, 2.26 to 170.00; p=0.007) and prior radiation (OR, 25.70; 95% CI, 2.37 to 280.00; p=0.008) significantly increased the risk of major complications. CONCLUSIONS: The use of an Ultraflex stent and prior radiation and/or chemotherapy may represent risk factors for complications following esophageal SEMS placement.

Manejo de un sangrado por úlcera posligadura de várices esofágicas mediante prótesis metálica autoexpandible: reporte de un caso y revisión de la literatura / Management of a Bleeding Ulcer by Post-esophageal Ligation of Varices with Self Expanding metal Stents: Case Report and Literature Review

Los inicios del manejo del sangrado variceal con compresión directa datan de 1930 por Westphal y colaboradores. Después, en 1950, se desarrolló el balón de Sengstaken-Blakemore, definido por Panes y colaboradores como la primera línea de terapia; en 1980, a nivel de várices esofágicas y en várices gástricas, se empleaba el balón de Linton-Nachlass (1, 2). Se presenta el caso clínico de un paciente con cirrosis hepática por hepatitis C, Child B, con várices esofágicas, a las cuales se les realizó ligadura en dos ocasiones por sangrado y en la segunda ocasión por inminencia de ruptura, esta última llevada a cabo dos semanas antes del evento. El paciente muestra un cuadro clínico compatible con hemorragia de vías digestivas altas masiva, con evidencia endoscópica de úlcera esofágica sangrante que no mejora con terlipresina, ni escleroterapia con adrenalina, ni compresión local con balón de acalasia. En consecuencia, como terapia de rescate se decide colocar un stent esofágico metálico autoexpandible parcialmente recubierto (por no contar con totalmente recubierto en el momento), con control parcial del sangrado. Es recomendable el uso del stent como terapia de rescate para el sangrado por várices esofágicas refractarias. Debe emplearse el diseñado especialmente para esta indicación (SX-Ella Danis), como un puente para poder estabilizar al paciente y realizar una terapia definitiva como la TIPS, tal cual como se procedió en un nuestro paciente.

Early treatment of bleeding varices with direct compression dates from the work by Westphal et al. in 1930. Later in 1950, Sengstaken-Blakemore developed their balloon which Panes and collaborators defined as the first line of therapy for esophageal varices in 1980 while they used the Linton-Nachlass balloon for gastric varices (1, 2). This study presents the clinical case of a patient with liver cirrhosis due to hepatitis C, (Child B) with esophageal varices which were ligated on two different occasions because of bleeding. On the second occasion a rupture was imminent and ligation occurred two weeks prior to the event. The patient presented a clinical picture compatible with massive upper gastrointestinal bleeding with endoscopic evidence of a bleeding esophageal ulcer that did not improve with terlipressin, sclerotherapy with adrenaline, or balloon dilatation. Consequently, it was to use a partially covered self-expanding metal esophageal stent for salvage therapy since a completely covered stent was not available at that time. Stenting achieved partial control of bleeding. We recommend the use of stenting with a stent specifically designed for this indication (SX-Ella Danis) as salvage therapy for refractory bleeding from esophageal varices. The stent can be used as a bridge to stabilize the patient in order to perform TIPS as the definitive treatment, as in the case of our patient.

Dosimetry comparison of esophageal stents carrying different diameters of radioactive 125I seeds / 介入放射学杂志

Objective To investigate the dose distribution of esophageal stents carrying different diameters of radioactive 125I seeds in tumor target area. Methods A laser scanner was used to scan a piece of blank paper on which circles of 12 mm, 14 mm and 16 mm diameter and a 5 cm scale were drawn. The data were stored in JPEF format on the computer desktop. According to the circular diameter, simulations of the corresponding esophageal stents were established, which were divided into group A, group B and group C. By using image conversion program, 17 images with 5 mm slice-distance were created for each group; the images were transmitted to the computer treatment planning system (TPS) to simulate the 8 cm long esophageal stents of different diameters. TPS was used to sketch the gross tumor volume (GTV) in order to simulate the esophageal stent border that was used as the inner boundary of GTV, which was expanded 0.5 cm outward to be used as the external boundary of GTV. Beginning from the fifth level, the 4 cm-long GTV was drawn with circles. Setting the same prescription dose, from the fifth level to the thirteenth level the 125I seeds with 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 mCi were successively loaded on the simulation of the esophageal stents. The distance between 125I seed layers was 1 cm; the average number of seeds distributed on each layer was 4 particles. The dose volume histogram (DVH) was obtained. The D90 (the dose received by 90% of the target) and V90 (the percentage of the GTV volume receiving 90% the prescription dose) were recorded.Result s The arithmetic mean D90 of group A, B and C was (77.24 ±19.92) Gy, (69.56 ±25.27) Gy and (56.38±20.08) Gy respectively, and no statistically significant differences existed between each other among the three groups (F=0.84,P=0.44). The V90 of group A, B and C was (77.76±30.73)%,(76.79±25.92)%and (64.10 ±32.49)% respectively, and no statistically significant differences existed between each other among the three groups (F=0.46,P=0.64). Conclusion When the diameter of radioactive esophageal stent is 12 mm, the activity of 125I seed of 0.6 mCi is recommended. When the diameter of radioactive esophageal stent is 14 mm or 16 mm, the activity of 125I seed of 0.7 mCi is recommended. Nevertheless, when the diameter of radioactive esophageal stent is 16 mm, distribution of every five 125I seeds on each layer is strongly recommended. These three kinds of esophageal stent diameter have no significant effect on the dosimetric parameters.

Esophageal stent covered with radioactive 125I seeds arranged at different distance：dosimetric ;comparison study / 介入放射学杂志

Objective To study the dose distribution in tumor target of radioactive esophageal stent covered with 125I seeds which are arranged at different distance. Methods According to the longitudinal and horizontal distance between the 125I seeds, the experiment was divided into group A (0.5 cm), group B (1.0 cm) and group C (1.5 cm). A sheet of white paper, on which a 2cm diameter circle was drawn and was marked with a 5 cm scale, was scanned with a laser scanner, and the scanning data were saved in JPEG format on the computer desktop. By using image conversion program, pictures of 17 layers with the layer space of 5 mm were created. The picture was transmitted to the computer treatment planning system (TPS) to simulate a 2 cm diameter and 8 cm length esophageal stent. Using TPS to delineate the tumor target area (gross tumor volume, GTV), which was used as the simulation of the inner boundary of the tumor target area, outward expansion of 0.5 cm being regarded as the outside border. An annular and 6cm length tube was delineated and it was used as the target area, and the same prescription dose was set, and in each group 125I seeds of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 mCi were successively loaded on the simulation of esophageal stent. With the help of TPS the DVH graph was obtained, and the D90 (the dose received by 90% of the target) and V90 (the percentage of the GTV receiving 90% the prescription dose) of the three groups were determined. The results were statistically analyzed. Results The arithmetic mean values of D90 of group A, B and C were (217.15± 19.92), (89.16±32.44) and (31.68±11.52) Gy respectively (F=159.18, P<0.05); and the arithmetic mean values of V90 of group A, B and C were (100.00±0.00)%, (86.47±21.36)%and (29.33±21.54)%respectively (F=32.11, P<0.05). Conclusion The 2 cm-diameter radioactive esophageal stent covered with 125I seeds, which have o.6mci activity and are arranged at 1.0cm distance in both longitudinal and horizontal directions, should be recommended in clinical practice.

The application of drug-eluting biodegradable magnesium alloy stent in treating esophageal benign stricture:current research status and prospect / 介入放射学杂志

Stent implantation plays a more and more important role in the treatment of benign esophageal stenosis. Metal stents are most commonly used in the clinical practice, which can be classified into permanent stents and temporary retrieval stents. Permanent implantation of metal stents is easy to cause complications such as inflammatory hyperplasia, in-stent restenosis, perforation, bleeding, etc. Temporary retrieval stents should be removed with one week after it is implanted in order to avoid esophageal scar tissue repair and in-stent tissue hyperplasia, which can cause difficulty in its removing and produce higher recurrence rate of esophageal restenosis. Clinically, drug-eluting stents have already been used in cardiovascular system procedures, but at present the gastrointestinal drug-eluting stents are still in development and animal experiment stage. Biodegradable magnesium alloy stents have been widely employed in cardiovascular system procedures. With the rapid development of biological engineering materials, drug-eluting magnesium alloy stent has become a hot spot and the frontier in research field. This paper aims to make a comprehensive review about the current research status and prospect of the drug-eluting magnesium alloy stents, focusing on the stent technology, stent molding, coating modification, and the treatment of drug-eluting.

Prevention and treatment of common complications after esophageal retrievable covered stent placement in children / 实用放射学杂志

Objective To explore risk factors,prevention and treatment of common complications of benign esophageal stenosis treated with the retrievable covered stents in children.Methods Fifteen cases,diagnosed as benign esophageal stenosis by barium esophagogram were treated with retrievable covered stents under fluoroscopy,Then the stents were removed after 2-3 weeks.The cases were followed-up and complications were observed.Results The stents were successful implanted in all cases.The diet was improved obviously after operation,and gradually transformed from liquid,semiliquid to normal feeding.At the same time,narrow section gradually expanded from 0.1-0.6 cm to 0.6-1.5 cm.Postoperative follow-up was in 1,2,3 weeks and 3 months.Main complications were stents shift in 5 cases,esophageal restenosis in 2 cases,esophageal-tracheal fistula in 1 case,postoperative dull pain behind sternum and foreign body sensation in 6 cases.Relevant preventions and treatments were performed based on different complications.Conclusion It should not be ignored that complications after covered stent placement are more in children than in adults,preventions and treatments should be taken positively.

Placement of a Self-Expanding Metal Stent to Treat Esophagogastric Benign Anastomotic Stricture via Retroflexed Ultrathin Endoscopy: A Case Report with a Video

Previous studies reported that ultrathin endoscope (UE) provides endoscopic guidance during insertion of a self-expanding metal stent (SEMS) without fluoroscopic monitoring in patients with upper gastrointestinal stenosis (benign or malignant) or postoperative esophageal leakage. According to the type of SEMS and level of the stenosis, the technique of the procedure is variable. Herein, we report a patient who underwent placement of a distal release esophageal SEMS to treat an esophagogastric anastomotic stricture via retroflexed UE.

Prevention of benign esophageal stent restenosis : an animal experiment / 中华消化内镜杂志

Objective To investigate the feasibility and preventive effect of benign esophageal restenosis by binding 125I seeds to upper esophageal stent through animal experiments.Methods Eight 125I seeds were evenly bound to upper normal esophageal stents for the animal experiments.A total of 32 beagle dogs were randomly assigned to 2 groups:experimental group,implanted with esophageal stents with eight 125I seeds (33.3 MBq),and the control (stents without 125I seeds).Four dogs of each group were killed at the 1 st,2nd,4th,and 8th week after imaging studies.The tissue of 2 cm upper stent underwent pathology analysis.Results All the novel stents were successfully implanted.No radioactive leak was detected by ECT.The lumen diameter of the top stent showed the tract gradually narrowed and at the 4th and 8th weeks,the experiment group narrowed more seriously compared with the control group and the difference was statistically significant (P ＜ 0.05).PCNA,ot-SMA mean optical density were significantly different in the 4th week.Both hydroxyproline and total amino acid increased progressively,with significant difference at the 4th and 8th weeks.The macroscopic and optical findings of the trachea and major vessels were basically the same in both groups.Conclusion The novel stent is feasible and safe for preventing benign esophageal restenosis and preventing benign esophageal stent restenosis.

Esophageal Stent for Cervical Esophagus and Esophagogastric Junction

Tumors in the cervical portion of the esophagus have traditionally been more difficult to manage. The implantation in the cervical esophagus is a technically demanding procedure. The implantation of modified self-expandable metal stents (SEMSs) was very effective perorally under endoscopic and fluoroscopic guidance. Experience with SEMS has revealed an increased risk of migration when either covered stents are used or a stent is implanted across the gastroesophageal junction. The modified, covered, esophageal stents appear to prevent stent migration and improve dysphagia in patients with malignant tumor stenosis at the esophagogastric junction. Besides heartburn, regurgitation is sometimes very distressing to patients and may lead to fatal aspiration due to reflux after stenting in esophagogastric junction. These symptoms can be reduced by the use of valved stent. The long S-shape valve is very effective in preventing acid reflux and valve inversion.

Esophageal intraluminal stents with 125I seeds for advanced esophageal cancer / 中华消化内镜杂志

Objective To evaluate the therapeutic effect of esophageal intraluminal stents with 125I seeds based on survival time and quality of life (QOL) of patients with advanced esophageal cancer.Methods A total of 37 patients with advanced esophageal cancer who underwent placement of esophageal 125I irradiation stent were followed up.The QOL was evaluated by QLQ-C30 and QLQ-OES18 questionnaires before the procedure, and 1 week and 3 months after.Results The mean survival time of 37 patients was 28 weeks, with 3-month and 6-month survival rates at 94.6% (35/37) and 51.4% (19/37), respectively.Compared with the baseline, the scores of emotional functioning(EF), cognitive functioning(CF),global quality of life(QL), fatigue(FA), pain(PA), financial difficulties(FI) and pain of QLQ-OES18(OESPA) assessed 1 week after stent placement increased (P0.05).Conclusion Implantation of 125I seeds combined with esophageal intraluminal stents may prolong survival time and improve QOL of patients with advanced esophageal cancer.

Clinical application of esophageal stent loaded with ~(125)I seeds: recent progress in research / 介入放射学杂志

Esophageal cancer is a common malignant tumor. Most patients have already in the late stage of the disease when the diagnosis is confirmed and have lost the surgery chance. In recent years, esophageal stent has been widely applied in the treatment of esophageal stenosis caused by esophageal cancer. The clinical experience shows that the esophageal stent can effectively solve the problem of dysphagia. However, the ordinary esophageal stent has no therapeutic effect on the esophagus tumor. The esophageal stent loaded with ~(125)I seeds can not only solve the dysphagia problem but also can treat the primary esophagus cancer with its brachytherapy effect. This article aims to review the clinical application and the up-to-date research progress of the esophageal stent loaded with ~(125)I seeds.

A Case of Refractory Esophageal Stricture Induced by Lye Ingestion and Treated by Temporary Placement of Newly Designed Self-Expanding Metal Stent and Wetting with Mitomycin C / 대한소화기내시경학회지

Ingestion of strong acids or strong alkalies may produces severe inflammation on the mucosa of the esophagus and this may also causes esophageal stricture. Several forms of non-operative dilatations have been utilized for the treatment of esophageal stricture and they have shown good results. Yet some patients do not achieve acceptable symptom relief despite of intensive dilatation. Temporary placement of esophageal stent has recently been used in some of these patients. Furthermore, mitomycin C has been used as a conservative treatment for refractive esophageal stricture in children, yet its efficacy has not been well established. We experienced a case of a 64-year old man with severe, recurrent esophageal stricture, and this was successfully managed by temporary placement of an esophageal stent, together with a spray of mitomycin C. We report on this case along with the review of the literature.

Usefulness of Double Esophageal Stent for Malignant Esophageal Stricture / 대한소화기내시경학회지

BACKGROUND/AIMS: Endoscopic self expandable metallic stent (SEMS) has become the palliative treatment of choice for inoperable malignant esophageal stricture. However, covered and uncovered stents carry limitations such as stent migration and tumor ingrowth, respectively. A double esophageal stent has been developed to overcome these problems. The aim of this study was to evaluate the usefulness of double esophageal stent (outer uncovered stent and inner covered stent) for palliation of malignant esophageal stricture. METHODS: Between February 2001 and November 2006, 32 patients with malignant esophageal stricture were treated with double esophageal stents. The patients were retrospectively assessed for the technical outcome, the clinical outcome and the complications of the process. RESULTS: Stent implantation was successful in all 32 patients (100%). The dysphasia score significantly improved from a mean of 3.22 to 1.63 (p<0.001) for all 32 patients. Eight patients had recurrent dysphagia due to stent overgrowth (6/32, 18%), stent migration (1/32, 3%) and tumor ingrowth (1/32, 3%). Symptomatic gastroesophageal reflux occurred in six patients (18%). Aspiration pneumonia occurred in two patients (6%). CONCLUSIONS: Double esophageal stent is effective for symptomatic relief of malignant esophageal stricture. It seems to reduce tumor ingrowth and stent migration, but it has limitations such as tumor overgrowth and GERD.

Esophageal stent insertion at the esophagogastrostomy site stenosis: Report of 3 cases / 대한흉부외과학회지

Although postanastomosis stenosis of esophageal reconstruction is rare but it is a very unwelcome complication. Previously, the problem was solved by balloon dilatation, reoperation, and feeding jejunostomy. However, balloon dilatation is not effective because of high recurrence rate, reoperation is difficult due to its operative approachableness and also jejunostomy is inconvenient for patients. Therefore, we inserted esophageal stent as a method of relieving postanastomosis stenosis. From Jan, 2001 to Dec, 2001, there were three patients with postanastomosis stenosis, who received esophageal stent insertion, one had case is benign esophageal stenosis, two had esophageal carcinoma. We followed up them over 12 months after inserting the stent, Dysphagia was improved, so we report that the clinical performance was satisfactory