Stents: Types, Indications, Deployment, and Clinical Applications Across Vascular Beds

A stent is a tubular scaffold deployed intraluminally to maintain patency of a vessel or duct. Modern stents are platform technologies adapted to diverse anatomies and pathologies.

Stent Classification

Category	Types	Key Features
Vascular	Bare-Metal (BMS)	316L stainless steel, CoCr, PtCr; high radial force; restenosis 20–30%
	Drug-Eluting (DES)	Sirolimus, Everolimus, Zotarolimus, Biolimus on polymer; restenosis 5–10%
	Bioresorbable (BRS)	PLLA, Mg alloy; temporary scaffold; vessel restoration; early thrombosis concerns
Non-Vascular	Biliary	Self-expanding metal (SEMS) or plastic; covered/uncovered; malignant/benign strictures
	Esophageal/Colonic/Tracheobronchial	SEMS; covered for fistula/seal; migration risk
Ureteral	Double-J (internal) or percutaneous; polyurethane; indwelling
Venous	Wallstent, Zilver; IVC, iliac, SVC, dialysis access

Major Vascular Indications

Coronary Artery Disease (CAD)

• Acute coronary syndrome (STEMI/NSTEMI): Primary PCI with DES.
• Stable ischemic: FFR/iFR-guided; DES for >70% stenosis + ischemia.
• Left main, bifurcation, CTO, in-stent restenosis — specialized techniques.

Peripheral Artery Disease (PAD)

• Femoropopliteal: Self-expanding nitinol DES (Zilver PTX, Eluvia) — flexible, fracture-resistant.
• Below-knee (BTK): DES for CLI (critical limb ischemia); tibial vessels.
• Aortoiliac: Balloon-expandable covered stents (Viabahn) for TASC C/D lesions.

Carotid Artery Disease

• CAS (Carotid Artery Stenting) + embolic protection: Alternative to CEA for high-surgical-risk, symptomatic ≥50% or asymptomatic ≥70% stenosis.
• Embolic protection devices (filter, proximal occlusion) mandatory.

Aortic Aneurysm (Endovascular Aneurysm Repair — EVAR/TEVAR)

• Stent-graft: Fabric (polyester/ePTFE) on nitinol/stainless frame.
• Excludes aneurysm sac from circulation; requires adequate sealing zones.
• Surveillance: CTA q6–12 mo for endoleaks (Type I–V), migration, sac enlargement.

Non-Vascular Applications

• Esophageal stricture: Benign (peptic, caustic, post-op) — temporary SEMS or dilation; Malignant — covered SEMS for palliation.
• Biliary stricture: Malignant (pancreatic, cholangiocarcinoma) — covered SEMS; Benign (post-cholecystectomy, PSC) — plastic stents serial exchange or temporary SEMS.
• Ureteral: Obstruction (stone, tumor, stricture) — Double-J stent; indwelling 3–6 mo, exchange q3 mo.
• Tracheobronchial: Malignant central airway obstruction — silicone (Dumon) or hybrid SEMS.

Deployment Principles

• Balloon-Expandable: Precise placement, high radial force (coronary, iliac, biliary).
• Self-Expanding (Nitinol): Conforms to tortuous vessels, external compression (SFA, carotid, venous, biliary).
• Sizing: 1:1 to 1.2:1 vessel:stent diameter (oversizing risks rupture; undersizing → migration).
• Landing Zones: Healthy vessel proximal/distal; length coverage + 5–10 mm margins.

Post-Stent Management

• DAPT (Dual Antiplatelet Therapy): Aspirin + P2Y12 inhibitor (clopidogrel, ticagrelor, prasugrel). Duration: Coronary DES 6–12 mo; BMS 1 mo; PAD 1–3 mo; CAS 1 mo.
• Surveillance: Clinical + imaging (duplex US, CTA, angiography) per vascular bed.
• Restenosis/Thrombosis: Repeat intervention (DES-in-DES, DCB, atherectomy).

Emerging Frontiers

• Drug-coated balloons (DCB) — leave nothing behind.
• Bioresorbable scaffolds (next-gen: thinner struts, faster resorption).
• Smart stents: Embedded sensors (pressure, flow, temperature).
• Gene-eluting, nanoparticle-coated, 3D-printed patient-specific.

Stents are transformative tools across medicine. Matching stent type, deployment technique, and antithrombotic regimen to the specific vascular bed and patient phenotype is the essence of modern endovascular practice.