What does stent consist of?

A stent is a medical device designed to keep blood vessels, ducts, or other pathways open in the body. The composition and structure of a stent vary depending on its intended use and location. Here are the main components and materials typically used in stents:

### Components of a Stent

1. **Frame:** The main structure of the stent, which provides the necessary support to keep the vessel or duct open.

2. **Coating:** Some stents have coatings that release drugs or other substances to prevent complications like restenosis (re-narrowing of the vessel).

### Common Materials Used in Stents

1. **Metallic Stents:**

  - **Stainless Steel:** Durable and widely used in various types of stents.

  - **Cobalt-Chromium Alloys:** Offer high strength and radiopacity (visibility under X-ray).

  - **Platinum-Chromium Alloys:** Provide excellent visibility and strength.

  - **Nitinol (Nickel-Titanium Alloy):** Known for its flexibility and shape memory properties, often used in self-expanding stents.

2. **Polymeric Stents:**

  - **Biodegradable Polymers:** Materials such as polylactic acid (PLA) and polyglycolic acid (PGA) that gradually dissolve in the body, often used in drug-eluting stents.

### Types of Stents

1. **Bare-Metal Stents (BMS):**

  - Made of metal without any coating.

  - Used to provide structural support to the vessel.

2. **Drug-Eluting Stents (DES):**

  - Coated with medication that is slowly released to prevent restenosis.

  - The coating typically includes a polymer that controls the release of the drug.

3. **Biodegradable/Bioresorbable Stents:**

  - Made from materials that dissolve over time, such as certain polymers or magnesium alloys.

  - Designed to provide temporary support and then be absorbed by the body.

4. **Covered Stents:**

  - Have a fabric or polymer covering to prevent tissue ingrowth.

  - Often used in the treatment of aneurysms or fistulas.

### Specialized Stents

1. **Vascular Stents:**

  - Used in arteries and veins to treat conditions like coronary artery disease, peripheral artery disease, and deep vein thrombosis.

2. **Gastrointestinal Stents:**

  - Used in the esophagus, stomach, intestines, and bile ducts to treat obstructions caused by tumors or strictures.

3. **Urological Stents:**

  - Used in the ureters and urethra to treat obstructions caused by kidney stones, tumors, or strictures.

4. **Bronchial Stents:**

  - Used in the airways to treat obstructions caused by tumors or other conditions.

### Summary

Stents are versatile medical devices made from various materials, including metals and polymers, designed to maintain the patency of vessels or ducts in the body. The choice of material and design depends on the specific medical application and the desired balance of strength, flexibility, and biocompatibility.