Introduction:
Endoluminal stenting is fixing a flexible, small tube-like hollow substance in the esophagus, gastrointestinal tract, bile duct, or colon. It is placed to release the obstruction caused by tumors or other occlusions. Certain conditions like esophageal strictures, benign or malignant lesions, or calcifications in bile ducts. They cause obstructions in the particular structure, and the functions are impaired. Endoluminal stent placement widens the narrowed structure and improves function.
What Is an Endoluminal Stent?
Endoluminal is a layer of tissue inside a tube, a duct, or any hollow (an empty gap or a space in the middle of a tube or any structure) organ in the body. At the same time, a stent is a small, compressible tubular substance with a hollow center for passage.
What Are the Types of Stents?
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Self-Expanding Metal Stent (SEMS): Self-expanding metal stents are the most commonly used. These stents are made of braided and interconnecting metallic rows and are arranged in a tubular form. They are coated with certain chemicals like nitinol (nickel-titanium alloy), polyurethane, and polyethylene and are called covered stents. These chemicals suppress tumor growth and are designed to be covered on the stents.
These stents appear small before deploying into the organ. Then, they are placed with the help of fluoroscopy and endoscopy. The stents are attached to a deploying device at one end of the endoscope. When the endoscope advances into the organ or the structure, the stent expands and is placed with the help of the deployment device. However, it is not a permanent cure. It prevents clogging for about three to four months. However, regular follow-ups are mandatory to check the stents for the formation of clogs or infections.
Covered stents are used in obstructions caused by benign lesions as they are easy to remove after removing the tumor. Also, they are used in managing malignant lesions as they suppress tumor growth. They also fix fluid leakages and fistula (an uncommon connection between organs or body parts). But, covered stents have a high risk of dislocation.
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Partially Covered Stents: Partially covered stents are partially coated self-expanding metal steel stents. They are used for blockages in the stomach, colon (part of the large intestine), and duodenum (first part of the small intestine). They are also used in the management of malignant tumors. And they have a very low risk of migration and are also easy to remove endoscopically.
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Self-Expanding Plastic Stents (SEPS): Self-expanding plastic stents are made of polyester in a monofilament braided form. It appears like a mesh. This mesh is covered with a silicone layer, a smooth inner layer, and the outer layer is structured. These plastic stents are favorably used in benign esophageal strictures. It promotes healing and gives a positive disease outcome. However, recent studies suggest that the migration risk is high in self-expanding plastic stents.
What Are the Indications for Endoluminal Stenting?
Esophagus:
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Malignant Esophageal Stricture: Malignant esophageal stricture is the abnormal narrowing of the esophagus caused by a cancerous growth in the tissues like the esophageal lining. In malignant esophageal stricture, there is progressive dysphagia (swallowing difficulty) that has developed recently and weight loss.
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Benign Esophageal Stricture: In benign esophageal stricture, there is also an abnormal narrowing of the esophagus, which was long-standing, intermittent, but non-progressive dysphagia. It is not cancerous.
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Malignant Esophageal Fistula: Esophageal fistula is an abnormal aperture or opening in the passage between the esophagus (a tubular structure that allows food passage from the mouth to the stomach) and the trachea (windpipe that connects the lungs and the throat). The openings may be one or more between the esophagus and the trachea.
Malignant esophageal fistula occurs due to a non-treatable underlying cancer like esophageal cancer that damages the lining of the esophagus and trachea.
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Benign Esophageal Fistula: Benign esophageal fistula occurs due to non-cancerous conditions like infections, injury, or ingesting a foreign body that may pierce and break the esophageal walls. Infections like tuberculosis are caused by Mycobacterium tuberculosis. It mainly affects the lungs and also affects the spinal cord, brain, and kidneys. Also, infections like histoplasmosis are acquired by inhaling spores from birds or bat droplets. Also, injury caused while intubating (placing a tube through the mouth or nose into the trachea for connection with an external machine for breathing) or during endoscopic procedures leads to esophageal fistula.
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Benign Esophageal Perforation: Benign esophageal perforation is a small opening or hole in the esophagus caused by infections or injury while intubating or placing catheters, or performing endoscopic procedures. Also, ingestion of sharp foreign objects also causes perforations.
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Variceal Bleeding: Veins that are swollen or enlarged are called varices. Variceal bleeding occurs when the veins rupture due to increased portal vein pressure (a portal vein is a blood vessel that drains blood from the gastrointestinal tract, gallbladder, pancreas, and spleen into the liver).
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Esophageal Anastomotic Leak: Anastomotic surgery is a connection between two structures. In esophageal anastomotic surgery, the proximal esophageal section is connected to the distal esophageal section. When there is a leak in the connected part, it is called an esophageal anastomotic leak.
Gastroduodenal:
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Roux-En-Y Gastric Bypass and Gastric Leak: Roux-en-Y gastric bypass is a bariatric surgery for weight loss when other regular weight loss techniques are not beneficial. It is done by creating a pouch in the stomach and connecting it directly to the small intestine. Unfortunately, after Roux-en-Y gastric bypass surgery, stomach or intestine contents sometimes leak as a complication.
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Roux-En-Y gastric bypass anastomotic stricture: Roux-en-Y gastric bypass involves connecting a newly created pouch in the stomach with the small intestine. When the contents from the connected structures leak, it is called Roux-en-Y gastric bypass anastomotic leak.
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Malignant Gastric Outlet Obstruction: Malignant gastric outlet obstruction is a mechanical obstruction or block in the pylorus (an opening that connects the stomach and the small intestine) or duodenum (first part of the small intestine) caused by compression or spread of a malignant lesion (cancerous tumor).
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Benign Gastric Outlet Obstruction: Peptic ulcers are the leading cause of benign gastric outlet obstruction. A peptic ulcer is an inflammation or tiny wound in the stomach, esophagus, or small intestine lining.
Colorectal:
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Malignant Colonic Stricture: Malignant colonic stricture is the narrowing of the colon due to cancerous tissue growth in the colon or the spread of cancer from other structures.
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Benign Colonic Stricture: Benign colonic stricture is an uncommon colon narrowing due to benign lesions like polyps in the colon.
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Anastomotic Leak: Anastomotic leak is the leakage of constituents from the structures connected together.
Gallbladder:
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Cholecystitis: Cholecystitis is the gallbladder's inflammation or swelling caused by the cystic duct's stone formation (a tubular structure that removes bile from the gallbladder). It blocks the tubular passage causing inflammation and pain.
Pancreas:
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Pancreatitis: Pancreatitis is the inflammation of the pancreas. The inflammation may be due to a block in the pancreatic duct or fluid build-up. Placing a stent narrows the duct and removes the block.
How Is Endoluminal Stenting Performed?
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An endoscope or fluoroscopy-guided pathway is followed in the placement of endoluminal stenting.
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The endoscope is a tubular structure that has a camera, light, and a few other instruments.
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The endoscope is inserted into the nose or mouth for stent placement in the esophagus, bile duct, and pancreas.
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The endoscope is inserted into the anus for stenting the colon or intestine.
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The endoscope is used along with fluoroscopy, in which a real-time video of the process is observed by passing x-rays into the body for a while.
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This helps better and more accurate placement of the stents.
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The endoscope is advanced into the internal organ, and the movements are viewed on a monitor outside.
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With the monitor's help, the stent deployment site is fixed.
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A guide wire is inserted soon after the endoscope is engaged.
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The stent is attached to a deployment device.
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The stent is placed after the guide wire is inserted. It guides the path to the obstructed passage, hence the name.
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The stent is then released into the narrowed part of the internal structure.
What Are the Complications of Endoluminal Stent Placement?
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Pain.
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Stent obstruction.
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Distortion of the stent.
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Tenesmus, an urge to pass stools though the bowels are empty.
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Rare bowel perforations.
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Covered stents have a high risk of migration.
What Is the Prognosis of Endoluminal Stent Placement?
Symptomatic relief and effective decompression of the structures are observed in about 70 percent of the patients. In patients with long-term stent placement, the tendency of block formation in the stent is low in patients with self-expandable metal stents. The patency (a condition of being unobstructed) rate is around 80 percent in six months and 72 percent after 12 months.
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Malignant Esophageal Stricture: The success rate is 95 percent for oral tolerance of liquids alone.
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Benign Esophageal Stricture: The success rate is around 6 to 56 percent, which varies according to the causes.
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Benign Esophageal Fistula: The success rate is around 64.7 to 71.4 percent, with complete resolution, and no further management is required.
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Malignant Esophageal Fistula: The success rate for fistula closure is around 70 to 100 percent.
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Benign Esophageal Perforation: The success rate is around 86 percent for both iatrogenic (caused during treatments or examination) and spontaneous perforations.
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Variceal Bleeding: The success rate is around 96 percent, and the bleeding stops within 24 hours.
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Esophageal Anastomotic Leak: The success rate is around 81.4 percent with a resolution of the leakage; no further management is needed. In addition, success depends on the site of the leak as well.
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Roux-En-Y Gastric Bypass and Gastric Leak: The success rate is around 80 to 94 percent, with tolerance to a liquid diet in three days.
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Roux-en-Y gastric bypass anastomotic stricture: The success rate is around 12.5 percent. Tolerant to oral diet with no further intervention.
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Malignant Gastric Outlet Obstruction: The success rate is around 80 to 92 percent for improvement in diet tolerance.
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Benign Gastric Outlet Obstruction: The success rate is around 90 percent, with no symptoms for 11 months.
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Benign Colonic Stricture: The success rate for resolution of the obstruction is around 76 to 95 percent.
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Malignant Colonic Stricture: The success rate for the resolution of the obstruction is around 80 to 92 percent.
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Anastomotic Leak: The success rate for cessation of leakage and stent removal is around 86.4 percent.
Conclusion:
Endoluminal stenting is the deployment of stents in the esophagus, gastrointestinal tract, gallbladder, or pancreas. It is a treatment modality to resolve blocks or narrow hollow structures. The block can be due to a tumor, injury, or other obstruction like fluid leakage. The stents are placed with the help of endoscopy and fluoroscopy. This helps the patient relieve symptoms like difficulty swallowing, pain, and discomfort. However, there are a few complications, like stent migration. Depending on the site and severity of the condition, placing an appropriate stent will prevent complications, improve the success rate of the stent placement, and improve the patient’s quality of life.
