Removal of Retrievable Self-Expandable Metallic Tracheobronchial Stents: An 18-Year Experience in a Single Center

State of the Science in Tracheal Stents: A Scoping Review

OBJECTIVE

Recent material science advancements are driving tracheal stent innovation. We sought to assess the state of the science regarding materials and preclinical/clinical outcomes for tracheal stents in adults with benign tracheal disease.

METHODS

A comprehensive literature search in April 2021 identified 556 articles related to tracheal stents. One-hundred and twenty-eight full-text articles were reviewed and 58 were included in the final analysis. Datapoints examined were stent materials, clinical applications and outcomes, and preclinical findings, including emerging technologies.

RESULTS

In the 58 included studies, stent materials were metals (n = 28), polymers (n = 19), coated stents (n = 19), and drug-eluting (n = 5). Metals included nitinol, steel, magnesium alloys, and elgiloy. Studies utilized 10 different polymers, the most popular included polydioxanone, poly-l-lactic acid, poly(d,l-lactide-co-glycolide), and polycaprolactone. Coated stents employed a metal or polymer framework and were coated with polyurethane, silicone, polytetrafluoroethylene, or polyester, with some polymer coatings designed specifically for drug elution. Drug-eluting stents utilized mitomycin C, arsenic trioxide, paclitaxel, rapamycin, and doxycycline. Of the 58 studies, 18 were human and 40 were animal studies (leporine = 21, canine = 9, swine = 4, rat = 3, ovine/feline/murine = 1). Noted complications included granulation tissue and/or stenosis, stent migration, death, infection, and fragmentation.

CONCLUSION

An increasing diversity of materials and coatings are employed for tracheal stents, growing more pronounced over the past decade. Though most studies are still preclinical, awareness of tracheal stent developments is important in contextualizing novel stent concepts and clinical trials. Laryngoscope, 2021.

Treatment of aerodigestive fistulas with a novel covered metallic Y-shaped segmented airway stent customized with the assistance of 3D printing

Background

The management of aerodigestive fistula remains challenging. An airway stent that matches well with the individual geometry of the airway is needed for the treatment of the aerodigestive fistula. This study aimed to evaluate the feasibility of a novel covered metallic segmented Y-shaped airway stent customized with the assistance of 3D printing in aerodigestive fistulas involving the carina and distal bronchi and to compare the flexibility of the novel stent with the conventional wholly knitted stent.

Methods

In the flexibility study, we measured the longitudinal bending force and spring-back force of the segmented stent and wholly knitted stent. Patient-specific stents that were individually customized with the assistance of 3D printing technology were implanted in 26 patients with aerodigestive fistulas. The technical success, clinical success, Karnofsky performance status (KPS), and stent-related complications were recorded.

Results

The bending force and spring-back force of the segmented stent were significantly lower than those of the wholly knitted stent. Stent deployment was technically successful in all patients. Clinical success was obtained in 21 patients. The KPS of patients after the stenting procedure improved significantly compared with that before stenting (P<0.001). During follow-up, granulation tissue proliferation, sputum retention, stent migration, and intolerance of the stent were found in 2, 5, 1, and 1 patient, respectively.

Conclusions

The segmented metallic Y-shaped airway stent had greater flexibility than the wholly knitted stent in an ex vivo setting. Implantation of the segmented stent individually customized with the aid of 3D printing is feasible in treating aerodigestive fistulas involving the carina and bronchi distal to the carina.

Technical Notes on Fluoroscopy-Guided Removal of Metallic Ureteral Stents

This manuscript describes various techniques for fluoroscopy-guided removal of metallic ureteral stents. Fifteen patients underwent 17 fluoroscopy-guided removal procedures of 22 metallic ureteral stents. The simple or modified snare or retrieval hook technique was primarily used for antegrade access, whereas the loop snare technique was primarily used for retrograde access. Overall 64.7% of the stents were removed using the initial retrieval technique, and 82.4% were removed using an adjunct technique. Procedure-related complications included hematuria in 41.2% of cases and resolved spontaneously in all patients. Fluoroscopy-guided removal of metallic ureteral stents is safe and effective.

Long-term outcomes of tracheal stents removal under fluoroscopy guidance: comparison of tracheal fistulas and tracheal stenosis

Background

Endoscopic removal is the most common method for removal of tracheal stents. Few studies have reported the technique of fluoroscopy-guided stent removal for tracheal fistula and tracheal stenosis. We aimed to study the safety and efficacy of fluoroscopy-guided stent removal as well as the optimal duration for stent usage.

Methods

We conducted a retrospective analysis of 152 patients who underwent fluoroscopy-guided stent removal from January 2011 to June 2017. Reasons for stent implantation were tracheal fistula in 85 patients (TF group), and tracheal stenosis in 67 patients (TS group). All patients underwent tracheal CT scans before stent removal and during follow up. The technical success rate, complications, and survival rate were compared between the two groups.

Results

The technical success rate of stent removal was 98.9 and 97.4%, respectively for the TF and TS group. Removal was routine for half of patients, and in the remainder, excessive granulation tissue was the common indications for stent removal, which was found after stenting at 142.1 ± 25.9 days in the TF group, and at 89.9 ± 15.0 day in the TS group. The total incidence of complications was 21.1 and 22.4%, respectively, for the TF and TS groups. Perioperative death occurred in one patient in the TF group, and two patients in the TS group. Recurrence of fistula or stenosis requiring re-stenting was the most comment complication in both groups. The 0.5-, 3-, 6-year survival rates were 90.3, 59.6, and 36.1% for TF group, and 80.4, 75.7, 75.7% for TS group.

Conclusions

Fluoroscopic removal of tracheal stents is safe and effective for both tracheal fistula and tracheal stenosis, with no significant difference in outcomes. Clinicians should pay attention to the risk of hemoptysis for patients with malignant tumors and a combination with endoscopic hemostasis may help improve its safety.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-020-01349-7.

A small bifurcated self-expanding metallic stent for malignant bronchial fistula or severe stenosis around the upper left carina

Background

Bifurcated self-expanding metallic stents have mainly been primarily used for the treatment of airway disease around the main carina, but few studies have reported the use of small bifurcated stents to treat malignant bronchial fistula or severe stenosis around the upper left carina.

Purpose

We aimed to determine the safety, feasibility, and efficacy of small metallic bifurcated stent placement in the upper left carina.

Material and Methods

Twenty-two patients with malignant bronchial disease were treated with small bifurcated stents. All bifurcated stents were custom-designed according to the measurement of CT measurements and placed under local anesthesia with fluoroscopic guidance. Clinical outcomes and CT imaging data were retrospectively analyzed.

Results

A total of 27 stents were used in 22 patients, with two stents removed immediately after placement due to stent insufficient dilation and failure of sealing fistula. Twenty patients underwent successful treatment, with a technical success of 90.9%. Thirteen complications were found in 9 (40.9%) patients. Five patients underwent successful stent removal due to failure of sealing fistula (n = 2) or because they were effectively cured (n = 3) during the follow-up period. Ten patients died of cancer, one patient died of chronic renal failure, and one died of myocardial infarction. The one-, three-, and five-year survival rates were 48.0%, 40.0%, and 32.0%, respectively. The median survival was 12.7 months.

Conclusion

Small bifurcated self-expanding metallic stents are a safe and effective treatment option for malignant bronchial fistula or severe stenosis around the upper left carina, but complications are relatively high. Further prospective studies are needed to evaluate alternative treatment options.

Design and Biomechanical Analysis of a Novel Retrievable Peripheral Vascular Stent

Structurally retrievable drug-eluting stents may have valuable clinical applications because they do not leave any foreign materials inside the patient's body. This article presents a novel design of retrievable peripheral vascular stent and the results from biomechanical analysis of its performance. Using the finite element analysis method, principal parameters of the stent were studied. Moreover, to ensure the practicability of the retrieval process, simulation, and in vitro experiments were performed. The retrieval force reached the maximum value when the whole retrievable part had been retrieved. Furthermore, the force was gradually increased during the retrieval process and remained constant after the main part had been retrieved. When the stent was being compressed, the maximum strain of the stent occurred at the connection between the stent's retrieval part and the main body part, at a value of 4%. The index of nonuniformity of the stent was too small to be counted both at the end of the compression and self-expansion processes. With the increase of moment, the bending stiffness (EI) of the stent decreased gradually. After bending moment was applied, the large strain region was mainly located in the stent's main body part rather than the retrieval part. The results of preliminary stent retrieval experiments demonstrated that the stent could be retrieved successfully. This novel retrievable stent displays promising biomechanical performance. The preliminary experiments demonstrated that the stent could be retrieved smoothly from the blood vessels.

Retrievable covered metallic segmented Y airway stent for gastrorespiratory fistula of carina or main bronchi

OBJECTIVE

To evaluate the feasibility of new retrievable covered metallic segmented Y airway stents modified with 3-dimensional (3D) printing for gastrorespiratory fistula involving carina or main bronchi.

METHODS

We designed a new retrievable covered metallic segmented Y airway stent to fit the anatomical characteristics of the carina region in individual patients. All stents were individually customized based on a 3D-printed mold. Six patients with gastrorespiratory fistula and aspiration pneumonia after esophagectomy underwent the stent implantation. The stents were retrieved when the fistula was cured or stent-related complications occurred.

RESULTS

Seven Y stents were successfully implanted and removed in 6 patients. All stents expanded well, and the fistulas were completely sealed. Aspiration pneumonia was controlled in 6 patients. The median Karnofsky Performance Status scores significantly improved after stenting compared with those before stent implantation (P = .024). Sputum retention was the most common complication after stenting and was treated with aspiration under bronchoscopy (33.33%). Excessive granulation tissue proliferation was found in 1 patient (16.7%) and was treated with cryotherapy. The indwelling time of the stent was 64 days (interquartile range, 52-69 days). After stent removal, bronchoscopy, gastroscopy, and computed tomography of the chest showed cured fistulas in all patients, and no stents showed fractures.

CONCLUSIONS

Retrievable covered metallic segmented Y airway stents modified with 3D printing appear to be feasible for the treatment of gastrorespiratory fistula involving carina or main bronchi.

Clinical outcomes of metallic Y-shaped covered stents for bronchopleural fistula around upper carina after lobectomy

BACKGROUND

Few studies have reported the placement of metallic Y-shaped covered stents (Y stents) for bronchopleural fistula around the upper carina.

METHODS

Eighteen patients were treated with Y stents insertion under the guidance of fluoroscopy. All covered stents were custom-designed and inserted to fit the upper carina anatomy. Clinical data and medical imaging data were analyzed retrospectively.

RESULTS

The stents were implanted successfully for the first time in 17 patients, and one patient needed a second attempt due to stent migration during withdrawal of the guide wires. In total, 19 small Y single-plugged stents were inserted in the upper carina and 5 large Y stents additionally in the main carina. Nineteen complications were observed in 14 patients, including 4 major complications. Stents were successfully removed in 12 patients due to complications or cure efficacy, for a median duration in place of 89.5 days. One patient lost follow-up. Nine patients were cured, and three had clinical improvement. One patient died of ventricular fibrillation the second day after the procedure and 4 patients died of tumors 7.8 to 91.7 months after stent placement. The 1-, 3-, and 5-year survival rates were 87.5, 80.8 and 80.8%, respectively.

CONCLUSIONS

Metallic Y stent placement is technically feasible, effective and safe for bronchopleural fistula disease around the upper carina.

Metallic small y stent placement at primary right carina for bronchial disease

Background

Metallic large Y stent placement has been used mainly for airway disease around the main carina. However, few studies have reported this treatment for bronchial disease around the primary right carina.

Methods

Twenty-eight patients were treated by small y stent. All stents were custom-designed and placed under fluoroscopic guidance. Clinical and imaging data were analyzed retrospectively.

Results

Thirty-one stents were successfully inserted in 28 patients. Twenty-five patients succeed at the first attempt (89.3%), and 3 patients needed a second attempt. Twelve complications occurred in 10 patients (35.7%). Stent restenosis and sputum retention were the most common complications. Five patients underwent successful stent removal due to complications or cure efficacy. During follow up, 17 patients died of tumors and one died of myocardial infarction. The 1-, 3-, and 5-year survival rates were 49.3, 19.6 and 19.6%, respectively.

Conclusions

Metallic small y stent placement is technically feasible, effective and safe for bronchial disease around the primary right carina.

Multiple Bifurcated Covered Self-Expanding Metallic Stents for Complex Tracheobronchial Fistulas or Stenosis

OBJECTIVE

We aimed to determine the safety and feasibility of bifurcated covered self-expanding stents for the treatment of complex tracheobronchial fistulas or stenosis.

METHODS

Twenty-eight patients were treated by multiple bifurcated covered airway stents (Micro-Tech Co. Ltd., Nanjing, China), including 18 cases of gastrobronchial or gastrotracheal fistula, 6 cases of bronchopleural fistula and 4 cases of severe tracheobronchial stenosis. The large bifurcated covered stent was placed at the main carina, and the small stents were inserted into primary right carina or secondary left carina. Clinical and imaging data were retrospectively analyzed.

RESULTS

Stents were successfully inserted in 27 patients at the first attempt. In total, 29 large bifurcated covered stents, 27 small bifurcated covered stents and 5 small bifurcated covered single-plugged stents were inserted. All patients with fistula could resume eating without coughing after the procedure. No perioperative death or severe complications occurred. Two patients underwent stent removal due to intolerance of stenting; the clinical success rate was 93% (26/28). Nineteen complications were found in 12 patients; 8 patients needed stent removal or replacement, for a major complication rate of 29% (8/28). Eight patients underwent successful stent removal due to complications. Fifteen patients died of tumors and one patient died of pulmonary infection. The median survival was 33 months. Fistula recurrence was found in one patient 5 months after stenting, and second small bifurcated covered stent was inserted.

CONCLUSIONS

Multiple bifurcated covered metallic stenting is effective and safe for complex tracheobronchial fistulas or stenosis, with good symptom palliation.