Self-Expanding Esophageal Stent

Self-expanding esophageal stent (self-expandable esophageal stents) complete introduction

The self-expanding esophageal stent is the core minimally invasive medical device for endoscopic treatment of esophageal stenosis, obstruction, and fistula. Relying on the shape memory / superelastic properties of its own material, it automatically expands and opens the esophageal lumen in the body, quickly solving swallowing difficulties. It is divided into three categories: metal stents, plastic film stents, and degradable stents. The most widely used in clinical practice is the self-expanding metal stent (SEMS) made of nickel-titanium alloy.

I. Working principle

The stent is compressed in a slender delivery tube when it leaves the factory and is guided into the esophageal stenosis lesion segment by endoscopy/endoscopy; After reaching the target position, it is released, and in the human body temperature environment, the memory material such as nickel-titanium alloy automatically restores the pre-set mesh structure, producing a continuous and gentle radial support force to expand the narrow esophagus and restore the feeding channel; The coated version can also seal esophageal-tracheal fistula and mediastinal fistula, preventing food and secretions from leaking into the airway.

II. Main structure and material

1. Main skeleton

The mainstream is made of nickel-titanium memory alloy wire woven / laser cut, with excellent super elasticity, corrosion resistance to gastric acid, high biocompatibility, and both ends are designed with trumpet / petal-shaped outward flanges to reduce displacement and reduce mucosal injury; Some stainless steel material stents have higher hardness and are suitable for severe stenosis.

2. Cover layer (optional)

· Bare stent: no covering, metal mesh exposed, prone to tumor/granulation tissue ingrowth, often used for short-term palliation;

· Partially covered: bare metal at both ends, covered with film in the middle, balancing the prevention of displacement and the prevention of tissue ingrowth, the most commonly used in clinical practice;

· Full coverage: Overall silicone / polyurethane wrapping, completely blocking tumor growth inward, can be removed endoscopically, suitable for benign stenosis, fistula closure, but the risk of displacement is slightly higher;Some have anti-reflux valves, which can alleviate stomach acid reflux.

3. Auxiliary structure: Recyclable traction ring, easy to remove the stent under endoscopy in the future.

III. Clinical indications

1. Malignant neoplasm (primary use)

Advanced esophageal cancer and cardia cancer cannot be surgically removed, palliative relief of dysphagia; Block the esophageal-tracheal fistula and esophageal mediastinal fistula formed by tumor rupture to avoid coughing and lung infection.

2. Benign esophageal lesions

Difficult-to-treat benign esophageal stenosis (postoperative anastomotic stenosis, chemical corrosion injury, radiotherapy-induced stenosis), esophageal perforation, postoperative anastomotic leak, temporary expansion support, and promotion of esophageal mucosal repair.

3. Other: Refractory obstruction caused by esophageal motility disorder, esophageal stenosis caused by external pressure (pressure from mediastinal tumor).

IV. Comparison of Stent Categories

Type Characteristics Suitable Scenarios Strengths and Weaknesses

Naked metal stent, no coating, strong radial support, palliative treatment of malignant stenosis, good support effect, but the tumor is easy to grow and difficult to remove.

Partially covered metal stent, bare metal fixed at both ends, covered with film in the middle. Most malignant stenosis, routine benign stenosis, prevent displacement, prevent tissue ingrowth, optimal comprehensive performance.

Entirely covered metal/plastic stent Entirely covered, can be completely removed Benign stenosis, fistula closure, short-term treatment Recyclable, blocking tumor invasion, high probability of displacement

Biodegradable biological stent, material can slowly degrade and absorb, benign stenosis, young patients, no need for secondary removal, later may appear granulation tissue hyperplasia.

V. Surgical methods

Minimally invasive procedure, no need to open the chest:

1. The narrow segment is located under endoscopy, and a guidewire is inserted;

2. Along the guide wire, push the stent delivery system to precisely release the stent;

3. The position of the stent can be confirmed by endoscopy, and the stent can be expanded well. The operation can be ended, and the patient can eat liquid food after a few hours of observation.