Numerical Study of the Biomechanical Behavior of a 3D Printed Polymer Esophageal Stent in the Esophagus by BP Neural Network Algorithm

Esophageal disease is a common disorder of the digestive system that can severely affect the quality of life andprognosis of patients. Esophageal stenting is an effective treatment that has been widely used in clinical practice.However, esophageal stents of different types and parameters have varying adaptability and effectiveness forpatients, and they need to be individually selected according to the patient’s specific situation. The purposeof this study was to provide a reference for clinical doctors to choose suitable esophageal stents. We used 3Dprinting technology to fabricate esophageal stents with different ratios of thermoplastic polyurethane (TPU)/(Poly-ε-caprolactone) PCL polymer, and established an artificial neural network model that could predict the radial forceof esophageal stents based on the content of TPU, PCL and print parameter. We selected three optimal ratios formechanical performance tests and evaluated the biomechanical effects of different ratios of stents on esophagealimplantation, swallowing, and stent migration processes through finite element numerical simulation and in vitrosimulation tests. The results showed that different ratios of polymer stents had different mechanical properties,affecting the effectiveness of stent expansion treatment and the possibility of postoperative complications of stentimplantation.

Endoscopic treatment of extreme esophageal stenosis complicated with esophagotracheal fistula: A case report

BACKGROUND At present,there is no unified and effective treatment for extreme corrosive esophageal stenosis(CES)with esophagotracheal fistula(ETF).This case had extreme and severe esophageal stenosis(ES)and ETF after ingesting an enzyme-based chemical detergent,resulting in a serious pulmonary infection and severe malnutrition.Upper gastrointestinal imaging showed that he had an ETF,and endoscopy showed that he had extreme and severe esophageal stricture.This case was complex and difficult to treat.According to the domestic and foreign lite-rature,there is no universal treatment that is low-risk.CASE SUMMARY A patient came to our hospital with extreme ES,an ETF,and severe malnutrition complicated with pulmonary tuberculosis 1 mo after the consumption of an enzy-me-based detergent.The ES was serious,and the endoscope was unable to pass through the esophagus.We treated him by endoscopic incision method(EIM),esophageal stent placement(ESP),and endoscopic balloon dilation(EBD)by using the bronchoscope and gastroscope.This treatment not only closed the ETF,but also expanded the esophagus,with minimal trauma,greatly reducing the pain of the patient.According to the literature,there are no similar reported cases.CONCLUSION We report,for the first time,a patient with extreme CES complicated with ETF,where the endoscope could not be passed through his esophagus but he could be examined by bronchoscopy and treated by EIM,ESP,and EBD.

A Case of Esophageal Perforation Presenting as Cavitary Pneumonia: Diagnostic and Therapeutic Challenges

Esophageal perforation, a rare condition, can arise from iatrogenic, traumatic, or spontaneous origins. Even when therapy is initiated within the first 24 hours, it is associated with a mortality rate of up to 25%. Due to the varied initial presentation, treatment may be delayed, leading to poorer outcomes. Here, we present a unique case of a 27-year-old schizophrenic patient who initially presented with acute respiratory failure and septic shock and was ultimately diagnosed with cavitary pneumonia secondary to esophageal perforation.

Acute upper gastrointestinal bleeding caused by esophageal right bronchial artery fistula:A case report

BACKGROUND Fistula between the esophagus and bronchial artery is an extremely rare and potentially life-threatening cause of acute upper gastrointestinal bleeding.Here,we report a case of fistula formation between the esophagus and a nonaneurysmal right bronchial artery(RBA).CASE SUMMARY An 80-year-old woman with previous left pneumonectomy and recent placement of an uncovered self-expandable metallic stent for esophageal adenocarcinoma was admitted due to hematemesis.Emergent computed tomography showed indirect signs of fistulization between the esophagus and a nonaneurysmal RBA,in the absence of active bleeding.Endoscopy revealed the esophageal stent correctly placed and a moderate amount of red blood within the stomach,in the absence of active bleeding or tumor ingrowth/overgrowth.After prompt multidisciplinary evaluation,a step-up approach was planned.The bleeding was successfully controlled by esophageal restenting followed by RBA embolization.No signs of rebleeding were observed and the patient was discharged home with stable hemoglobin level on postoperative day 7.CONCLUSION This was a previously unreported case of an esophageal RBA fistula successfully managed by esophageal restenting followed by RBA embolization.

Analysis of mechanical performance of braided esophageal stent structure and its wires

This paper aims to find the relationship between the structural parameters and the radial stiffness of the braided stent and to understand the stress distribution law of the wires. According to the equation of the space spiral curve, a three-dimensional parametrical geometrical model is constructed. The finite element model is built by using the beam-beam contact elements and 3D beam elements. The constituent nitinol wires are assumed to be linear elastic material. The finite element analysis figures out that the radial stiffness of the stent and the stress distribution of the wires are influenced by all the structural parameters. The helix pitch of the wires is the most important factor. Under the condition of the same load and other structural parameters remaining unchanged, when the number of wires is 24, the stress of the wire crosssection is at the minimum. A comparison between the vitro experimental results and the analytical results is conducted, and the data is consistent, which proves that the current finite element model can be used to appropriately predict the mechanical performance of the braided esophageal stents.

Self-expanding metallic esophageal stents:A long way to go before a particular stent can be recommended

We agree that the covered self-expanding metal stents (SEMSs) fare better than the uncovered stents as recurrent dysphagia due to tumor ingrowth is common with uncovered stent. Recent American College of Gastroenterology Practice Guideline on the Role of Esophageal Stents in Benign and Malignant Diseases concludes that SEMSs cannot be routinely recommended in conjunction with chemo-radiation. The comparison of ultraflex and choostent in the Italian study found no difference in the palliation of dysphagia, rate of complications and survival rate.

Repair of an aberrant subclavian arterioesophageal fistula following esophageal stent placement

A fistula formation between the esophagus and an aberrant right subclavian artery is a rare but fatal com-plication that has been mostly described in the setting of prolonged nasogastric intubation and foreign body erosion. We report a case of a young morbidly obese patient who underwent sleeve gastrectomy that was complicated by a postoperative leak at the level of the gastroesophageal junction. A covered esophageal stent was placed endoscopically to treat the leak. The pa-tient developed massive upper gastrointestinal bleeding secondary to the erosion of the stent into an aberrant retroesophageal right subclavian artery twelve days after stent placement. She was ultimately treated by endovascular stenting of the aberrant right subclavian artery followed by thoracotomy and esophageal repair over a T-tube. This case report highlights the multidis-ciplinary approach needed to diagnose and managesuch a devastating complication. It also emphasizes the need for imaging studies prior to stent deployment to delineate the vascular anatomy and rule out the possi-bility of such an anomaly in view of the growing popu-larity of esophageal stents, especially in the setting of a leak.

The Placement of Esophageal Stents in Different Esophageal Disease Related Conditions—A Review

In the past, the esophagus diseases causing the patient to unable to intake oral diet such as esophageal strictures, leaks, tracheoesophageal fistulas, etc. were managed by surgical interventions and parenteral nutrition to meet the demand of the body. After the development of technique of stent placement in esopahgus, there was revolutionary change in the management of such conditions promoting patients to take diet orally and improve their nutritional status as well as quality of life. Different types of commercial stents are available in the market with their own pros and cons. Our aim of this study was to review the different stents being used currently in the clinical practice, comparing the stents on their therapeutic outcome and complications, optimal timing of removal of stents for benign conditions and the methods studied by different clinicians to lower the rate of complications and reinterventions.

Successful management of therapy-refractory pseudoachalasia after Ivor Lewis esophagectomy by bypassing colonic pull-up:A case report

BACKGROUND Gastric pull-up after esophagectomy is still a demanding surgical procedure and associated with considerable morbidity such as anastomotic leaks,fistulas or stenoses.These complications are usually managed by endoscopy,but in extreme cases multidisciplinary management including reoperations may be necessary.Here,we report managing therapy-refractory pseudoachalasia after Ivor Lewis esophagectomy by bypassing colonic pull-up.CASE SUMMARY A 70-year-old male with dysphagia and regurgitation after esophagectomy with gastric pull-up reconstruction was transferred to our tertiary hospital.Since endoscopic approaches including balloon dilatation and stenting failed,retrosternal colonic pull-up with Roux-en-Y reconstruction was performed with no subsequent adverse events.CONCLUSION Secondary colonic pull-up is a demanding but successful surgical procedure in patients suffering from therapy-refractory complaints after esophagectomy with gastric pull-up reconstruction.

Utilization of chest tube as an esophagus stent in pediatric caustic injuries:A retrospective study

BACKGROUND The management of caustic esophageal burns in the pediatric population has changed over the years,while the most optimal management with regards to effectiveness,availability,and cost-beneficent stays controvertible.AIM To describe how to utilize a chest tube for esophageal stenting in pediatrics.METHODS Data regarding the etiology,treatment,and complications of caustic injury in pediatrics over 10 years was collected retrospectively.Furthermore,data regarding the patient's follow-up who underwent esophageal chest tube(ECT)were collected.The ECT was prepared by carving a narrowed section in the chest tube while maintaining the radiopaque section.The ECT will then be positioned from the cricopharyngeal and exited through the nostril and fixed on the patient's cheek.RESULTS During the period of our study,data from 57 patients with an average age of 2.5 years(range 1-12;SD=1.7)were obtained.The results showed that 89%of esophageal injury was due to alkaline and 9.4%were caused by acidic agents.The treatment methods showed that 29 patients(50.8%)recovered with dilatation alone.In 16 patients(28.06%),the esophageal repair was performed by using the colon,and in 5 patients(8.7%),other surgical methods were used and in 7 patients(12.2%),the ECT stents were used.ECT was inserted in 7 cases with a mean age of 2(range:1.5-3)years who were classified as grade IIB or III.Grading was performed by endoscopy assessment on the first day.Antibiotics and corticosteroids were administrated as initial medical management for all patients.ECT implantation was done during the first 8 d for 5 out of 7 cases(mean:3.8 d).For the 2 patients,ECT was used after 27(patient 6)d and 83(patient 7)d.The reason for late stenting in these patients was a postponed referral to our center,in which patient 7 even received 4 dilation episodes before visiting our center.ECT was removed after an average of 44 d in the first 5 patients,while in the other 2 patients(6 and 7)was 2 and 1 wk,respectively.There was no complication related to,or failure of,stent placement.It is worth mentioning that none of the 7 ECT cases required gastrostomy or jejunostomy.CONCLUSION The ECT method introduced in our study can be used as a broadly available,economic,and easyuse facility for esophageal stenting,particularly in developing countries and emergency departments which have limited access to modern equipment.Further multicenter studies with higher volume patients are required for further deployment of this method.

In vitro Degradation of Pure Mg for Esophageal Stent in Artificial Saliva

Magnesium and its alloys as biodegradable implant materials can be potentially used in cardiovascular and orthopedic devices. However, few studies have focused on its application in esophageal stents. In this paper, time-lapse degradation characteristics of pure Mg were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, hydrogen evolution, pH and electrochemical measurements after immersion in artificial saliva for different times. Results revealed that a dense degradation product film formed on samples, which mainly consisted of two kinds of layers： one was calcium phosphate compounds with different structures; the other was thin magnesium hydrate layer close to the substrate. Less pH increase and low degradation rate were ob- served in the first 5 days of immersion, which can be ascribed to the formation of a thicker and denser layer on the sample surface with increasing immersion time. And then there was an increase in degradation rate and pH values; the deposition layer remained almost intact after immersion for 6 and 8 days. After 10 days of immersion, the degradation rate and pH value remained stable, and the calcium phosphate layer was delaminated and the inner magnesium hydrate layer was exposed. This study indicated that pure Mg exhibited desirable degradation resistance in artificial saliva, which provided magnesiumbased materials with the potential to be used as esophageal stents.

Investigation of Mg–Zn–Y–Nd alloy for potential application of biodegradable esophageal stent material

In recent years,due to unhealthy dietary habits and other reasons,advanced esophageal cancer patients are on the rise,threatening human health and life safety at all times.Stents implantation as an important complementary or alternative method for chemotherapy has been widely applied in clinics.However,the adhesion and proliferation of pathological cells,such as tumor cells,fibroblasts and epithelial cells,may interfere the efficacy of stents.Further multiple implantation due to restenosis may also bring pain to patients.In this contribution,we preferred a biodegradable material Mg–Zn–Y–Nd alloy for potential application of esophageal stent.The hardness testing showed that Mg–Zn–Y–Nd alloy owned less mechanical properties compared with the commercial esophageal stents material,317L stainless steel(317L SS),while Mg–Zn–Y–Nd displayed significantly better biodegradation than 317L SS.Cell apoptosis assay indicated Mg–Zn–Y–Nd inhibited adhesion and proliferation of tumor cells,fibroblasts and epithelial cells.Our research suggested potential application of Mg–Zn–Y–Nd alloy as a novel material for biodegradable esophageal stent.