What are the different types of stents?

Stents are categorized based on their use in different parts of the body and the materials used to manufacture them. Here are the primary types of stents:

### 1. **Coronary Stents:**

  - **Purpose:** Used to keep coronary arteries open in patients with coronary artery disease (CAD) or after a heart attack.

  - **Types:**

    - **Bare-Metal Stents (BMS):** Made of metal without any coating, providing structural support but may be prone to restenosis (re-narrowing of the artery).

    - **Drug-Eluting Stents (DES):** Coated with medications that help prevent restenosis by inhibiting cell proliferation and reducing scar tissue formation.

### 2. **Peripheral Stents:**

  - **Purpose:** Used to maintain open blood vessels in the peripheral arteries (such as those in the legs) affected by peripheral artery disease (PAD).

  - **Types:**

    - **Self-Expanding Stents:** Made from materials like nitinol, which expand on their own once deployed.

    - **Balloon-Expandable Stents:** Expanded by inflating a balloon that is part of the delivery system.

### 3. **Ureteral Stents:**

  - **Purpose:** Used to relieve obstructions in the ureters, which carry urine from the kidneys to the bladder.

  - **Types:**

    - **Double-J Stents:** Shaped like a J at both ends, allowing them to stay in place in the ureter and bladder.

    - **Single-Pigtail Stents:** One end is coiled to prevent migration, with the other end often positioned in the bladder.

### 4. **Tracheal Stents:**

  - **Purpose:** Used to support the trachea (windpipe) in cases of tracheal collapse or obstruction, particularly in small breed dogs.

  - **Types:**

    - **Self-Expanding Stents:** Often made from metal, designed to expand and support the trachea once deployed.

    - **Silicone Stents:** Flexible and designed to conform to the trachea's shape.

### 5. **Esophageal Stents:**

  - **Purpose:** Used to keep the esophagus open in cases of strictures, tumors, or obstructions.

  - **Types:**

    - **Metal Stents:** Made of stainless steel or nitinol, used for more permanent solutions.

    - **Plastic or Silicone Stents:** Used for temporary or less invasive applications.

### 6. **Biliary Stents:**

  - **Purpose:** Used to relieve obstructions in the bile ducts, often due to tumors, gallstones, or strictures.

  - **Types:**

    - **Plastic Stents:** Typically used for short-term or temporary relief.

    - **Metal Stents:** More durable and used for long-term management.

### 7. **Gastrostomy Stents:**

  - **Purpose:** Placed in the stomach to provide a feeding route for patients who cannot eat by mouth.

  - **Types:**

    - **Self-Expanding Metal Stents:** Provide a durable option for long-term feeding access.

    - **Silicone Stents:** Flexible and used for temporary solutions.

### 8. **Ductal Stents:**

  - **Purpose:** Used in various ducts, such as the pancreatic duct, to treat conditions like pancreatitis or ductal strictures.

  - **Types:**

    - **Plastic Stents:** Commonly used for temporary applications.

    - **Metal Stents:** Used for more permanent solutions.

### 9. **Intraluminal Stents:**

  - **Purpose:** Used to support various luminal structures within the body, such as the intestines or bronchi.

  - **Types:**

    - **Self-Expanding Metal Stents:** Used for their flexibility and ability to expand after deployment.

    - **Balloon-Expandable Stents:** Used for precise expansion and support.

### 10. **Endovenous Stents:**

  - **Purpose:** Used in veins, particularly in cases of chronic venous insufficiency or deep vein thrombosis.

  - **Types:**

    - **Metal Stents:** Provide structural support to veins.

    - **Plastic Stents:** Less commonly used, typically for temporary applications.

### Summary

Stents are versatile medical devices designed to support and keep open various passages in the body. They come in different types and materials tailored to specific medical needs, including coronary arteries, peripheral arteries, ureters, trachea, esophagus, bile ducts, and other anatomical structures. Proper selection and placement of stents are crucial for effective treatment and management of obstructions or narrowing in these passages.