What is the preferred shape for an esophageal stent flange?

Safety and Efficacy of a Large-Bore Biliary Metallic Stent for Malignant Biliary Obstruction

Self-expandable metallic stents (SEMSs) are typically inserted in patients with unresectable malignant biliary obstruction. However, SEMSs are susceptible to occlusion. To overcome this issue, we developed a large-bore, dumbbell-shaped, fully covered SEMS (FCSEMS-L) and compared its efficacy and safety with those of a conventional FCSEMS (FCSEMS-C) in patients with malignant biliary obstruction. Methods: Patients with unresectable distal malignant biliary obstruction were retrospectively enrolled between January 2011 and February 2021. All patients underwent endoscopic insertion of FCSEMSs. Recurrent biliary obstruction (RBO), patient survival time, complications, and prognosis were analyzed. Results: RBO occurred in 31 patients (35.6%) who received an FCSEMS-L, and in 34 (45.9%) who received an FCSEMS-C. Stent occlusion occurred in 19 patients (21.8%) who received an FCSEMS-L, and in 22 (29.7%) who received an FCSEMS-C. Stent migration occurred in 12 patients (13.8%) with an FCSEMS-L and 12 (16.2%) with an FCSEMS-C. The median time to RBO (TRBO) was 301 days with an FCSEMS-L and 203 days with an FCSEMS-C. The median survival time was 479 days with an FCSEMS-L and 523 days with an FCSEMS-C. The TRBO and patient survival time did not significantly differ between the two groups. Conclusions: There were no significant differences in efficacy and complication rates between the fully covered large bore SEMSs and conventional fully covered SEMSs.

Preliminary Experience With a Novel Metallic Segmented Transcordal Stent Modified With Three-Dimensional Printing for Inoperable Malignant Laryngotracheal Stenosis

Background

This study aims to assess the feasibility of a novel metallic segmented transcordal stent modified with three-dimensional (3D) printing for treating inoperable malignant laryngotracheal stenosis and the tolerability of the stent.

Methods

This was a retrospective study. The stents were individually customized with the aid of 3D printing model based on the anatomic features of each patient’s airway. The stent was composed of two separate segments that corresponded to the larynx and the upper trachea. The stents were barrel-shaped at the proximal end to prevent migration. The proximal end of the stent was located slightly above the vocal cord. The technical and clinical success of stenting procedure, patient tolerability, and stent-related complications of patients were evaluated.

Results

Ten patients with dyspnea caused by malignant laryngotracheal stenosis underwent implantation of such stents. Technical and clinical success of the stenting procedure were achieved in all patients. For all patients, basic communication in life could be maintained by speaking softly. During follow-up, one patient showed intolerance to the stent, and the stent was retrieved 2 weeks after stenting. Stent migration was found in one patient, and the position of the stent was readjusted. Granulation tissue proliferation was found in two patients and was treated with cryotherapy by bronchoscopy. There were no deaths associated with stenting.

Conclusions

The individually customized metallic segmented transcordal stent is feasible and tolerable for patients with inoperable malignant laryngotracheal stenosis. The implantation of this stent may serve as a novel alternative treatment for patients who are not suitable for surgery or tracheotomy.

A HYBRID TUBULAR BRAID WITH IMPROVED LONGITUDINAL STIFFNESS FOR MEDICAL CATHETER

Medical catheters are widely used in various medical procedures, such as diagnostics, biopsies and air change. A desirable catheter needs to be flexible for low discomfort, and stiff in longitudinal direction for easy manipulation. Tubular braid is often employed as reinforcement structure for catheters, which plays an important role in the overall mechanical properties. Current tubular braids adopt identical braiding angles for all the yarns, resulting in limited longitudinal stiffness. In this paper, a novel hybrid braid with different braiding angles for the two sets of yarns is proposed and analyzed. Both experimental and numerical results show that the hybrid braid has a higher longitudinal stiffness than the uniform one due to the geometrical incompatibility generated by the hybrid braiding angles. The effects of design parameters are also investigated through a parametric study, and an increase of 418.3% is achieved in the optimum case. In addition, the bending flexibility of the hybrid braid is found to be comparable with the uniform one. The new structure shows great promise for engineering applications where high longitudinal stiffness is required.

A foldable manipulator with tunable stiffness based on braided structure

Minimally invasive surgery (MIS) has recently seen a surge in clinical applications due to its potential benefits over open surgery. In MIS, a long manipulator is placed through a tortuous human orifice to create a channel for surgical tools and provide support when they are operated. Currently the relative large profile and low stiffness of the manipulators limit the effectiveness and accuracy of MIS. Here we propose a new foldable manipulator with tunable stiffness. The manipulator takes a braided skeleton to enable radial folding, whereas membrane is used to seal the skeleton so as to adjust stiffness through creating negative pressure. We demonstrated experimentally, numerically, and analytically that, a flexible and a rigid state were obtained, and the ratio of bending stiffness in the rigid state to that in the flexible state reached 6.85. In addition, the manipulator achieved a radial folding ratio of 1.95. The proposed manipulator shows great potential in the design of surgical robots for MIS. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B, 2019.

A simplified technique of esophageal self-expandable metallic stent placement without fluoroscopic and endoscopic guidance for treating esophageal carcinoma

BACKGROUND/AIMS

Self-expandable metallic stent (SEMS) placement with fluoroscopic guidance is a commonly used technique to relieve obstruction in patients with esophageal carcinoma. However, it has disadvantages such as radiation exposure. SEMS placement with endoscopic guidance also has the disadvantages of causing discomfort to patients as the endoscope and SEMS assembly are simultaneously used and it needs two experts for the procedure to be performed. To overcome these disadvantages, a simplified technique for SEMS placement was developed that does not require fluoroscopic or endoscopic guidance. Our objective was to compare the efficacy and safety of this simplified technique with the conventional SEMS placement method.

MATERIALS AND METHODS

This is a retrospective study including patients with esophageal carcinoma who underwent SEMS placement for the palliation of dysphagia.

RESULTS

Sixty-two patients were placed on stents for the palliation for esophageal carcinoma, with 46 patients in the conventional technique group (group A) and 16 in the simplified technique group (group B). The duration of the procedure was considerably lesser in group B than in group A (2 min 53 s vs. 15 min 4 s, p=0.001). The technical success rate achieved in groups A and B were 97.82% and 100%, respectively. SEMS placement required two experts in the conventional technique whereas the simplified technique required only one expert.

CONCLUSION

The advantages of the simplified technique are as follows: technical ease, cost-effectiveness, no exposure to radiation, requirement of minimal manpower, and less time-consuming; these advantages make it the technique day-care procedure.