Endovascular Techniques

Endovascular Basics & Access - Gateway to Vessels

Endovascular: Minimally invasive procedures within vessels.

• Advantages: ↓morbidity, ↓hospital stay, ↓pain; local anesthesia.

• Disadvantages: Radiation, contrast, restenosis, cost, technical skill.

• Patient Selection: Comorbidities, vascular anatomy.

• Access Sites:

  • Common Femoral Artery (CFA): Preferred; antegrade/retrograde.
    • 📌 Seldinger Technique: 1. Needle → 2. Wire → 3. Needle out → 4. Sheath/catheter.
  • Alternatives: Brachial, radial, popliteal.

• Basic Tools:

  • Needles (Seldinger); Guidewires (0.035", 0.018", 0.014"; J-tip, angled, hydrophilic, stiff); Catheters (diagnostic e.g. pigtail, guiding); Sheaths (introducer, French).

• Imaging:

  • Fluoroscopy (C-arm), DSA, roadmapping. IVUS/OCT for detail.

⭐ Seldinger technique: cornerstone for percutaneous arterial access.

PTA & Stenting - Pipe Perfectors

• Percutaneous Transluminal Angioplasty (PTA):
  • Mechanism: Plaque fracture, vessel stretching, controlled dissection.
  • Indications: Focal stenosis/occlusion (PVD, renal artery stenosis).
  • Balloons: Compliant (sizing), Non-compliant (high-pressure for resistant lesions).
• Stents:
  • Indications: Post-PTA (flow-limiting dissection, elastic recoil), restenosis prevention.
  • Types:

    Stent Type	Key Feature / Drug (DES)	Primary Uses
    Balloon-Expandable	High radial force, precise	Renal, iliac a.
    Self-Expanding	Flexible, conformable	SFA, carotid a.
    BMS	Mechanical scaffold	General use
    DES	Drugs (Sirolimus/Paclitaxel); ↓neointimal hyperplasia	Coronary, PVD (high restenosis risk)
    Covered (Stent-Graft)	PTFE-lined; seals	Aneurysms, perforations, AVFs

• Antiplatelet Therapy:
  • DAPT: Aspirin + Clopidogrel (or Ticagrelor/Prasugrel). Duration varies by stent/location.

⭐ Drug-eluting stents significantly reduce in-stent restenosis rates compared to bare-metal stents, particularly in smaller vessels or diabetic patients.

Specialized Tools & Aneurysm Repair - Advanced Arsenal

• Atherectomy Devices: Plaque debulking/removal.

  • Types: Directional, rotational, orbital, laser.
  • Indications: Calcified/ostial lesions, PTA/stenting alternative.

• Thrombectomy/Embolectomy Devices: For thrombus/embolus removal.

  • Types: Aspiration, mechanical fragmentation, rheolytic.
  • Indications: Acute limb ischemia, DVT, PE.

• Endovascular Aneurysm Repair (EVAR): For Abdominal Aortic Aneurysm (AAA).

  • Device: Stent-graft.
  • Indications: Diameter >5.5cm, symptomatic, rapid expansion.
  • Key Anatomy: Adequate neck length/angulation, access vessel diameter.

• Thoracic Endovascular Aortic Repair (TEVAR): For thoracic aortic aneurysms/dissections. Device: Stent-graft.

• Endoleaks: Persistent aneurysm sac perfusion outside graft.

  • Types I-V (📌 "SEB-PT"):
    • I: Seal zone (graft ends)
    • II: Branch (retrograde flow, e.g., lumbar, IMA)
    • III: Fabric tear / Junctional separation
    • IV: Porosity (graft wall)
    • V: Endotension (sac expansion, no visible leak)

⭐ Type II endoleak, from branch vessels (e.g., lumbar artery, IMA), is the most common type following EVAR and often managed conservatively initially.

Complications & Post-Procedure - Navigating Pitfalls

• Access Site:
  • Hematoma, pseudoaneurysm (Doppler: to-and-fro flow; Rx: compression, thrombin inj.), AV fistula, dissection, thrombosis, infection.
• Systemic:
  • Contrast-Induced Nephropathy (CIN): Risks: CKD, DM, dehydration, high contrast volume. Prevent: Hydration, low/iso-osmolar contrast, ↓contrast volume, N-acetylcysteine.
  • Allergic reaction.
• Procedure-Related:
  • Distal embolization ("trash foot"), vessel perforation/rupture, dissection, radiation injury.
• Stent-Related (Long-term):
  • In-stent restenosis (neointimal hyperplasia), stent thrombosis (DAPT adherence crucial!), stent fracture, migration.
• Post-Procedure:
  • Monitoring; surveillance imaging (Duplex USG, CT Angio for EVAR/TEVAR).

⭐ Acute stent thrombosis is a dreaded complication often linked to premature discontinuation of dual antiplatelet therapy (DAPT).

High‑Yield Points - ⚡ Biggest Takeaways

• Seldinger technique is fundamental for vascular access.
• Guidewires (hydrophilic, stiff) and catheters are core endovascular tools.
• Angioplasty (PTA) dilates stenoses; stents (BMS, DES) maintain vessel patency.
• EVAR/TEVAR is preferred for suitable aortic aneurysms over open repair.
• Complications: access site issues (hematoma, pseudoaneurysm), embolization, contrast nephropathy.
• Covered stents (stent-grafts) treat aneurysms, dissections, and perforations.
• Mechanical thrombectomy is vital for acute limb ischemia and stroke management.