Embolization Procedures

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Embolization: Core Concepts - Sealing the Pipes

  • Definition: Therapeutic, catheter-guided endovascular occlusion of blood vessels.
  • Primary Aims:
    • Control/prevent hemorrhage (e.g., GI bleed, trauma, postpartum, epistaxis).
    • Devascularize tumors (e.g., HCC, RCC, fibroids) or abnormal tissue (e.g., AVMs, AVFs).
    • Reduce blood flow pre-operatively or for palliation.
  • Mechanism: Precise, angiographically-guided delivery of embolic agents to target sites.
  • Desired Physiological Effect: Achieve stasis, ↓ blood flow, leading to target ischemia, necrosis, or thrombosis, while sparing non-target tissues.
  • Access Routes: Primarily femoral artery; alternatives include radial, brachial arteries, or venous access.

⭐ Uterine Artery Embolization (UAE) is a key minimally invasive option for symptomatic uterine fibroids, offering uterine preservation and symptom relief.

Embolic Materials - Blocker's Arsenal

  • Temporary (Absorbable):
    • Gelfoam (Gelatin Sponge):
      • Mechanism: Mechanical block, promotes thrombosis.
      • Resorption: Weeks to months.
      • Forms: Pledgets, powder, slurry.
    • Autologous Blood Clot:
      • Mechanism: Physiological thrombosis.
      • Resorption: Variable, often rapid lysis.
  • Permanent (Non-Absorbable):
    • Particulate Agents:
      • Polyvinyl Alcohol (PVA): Irregular particles (100-1200 µm). Mechanical occlusion.
      • Microspheres (e.g., Embospheres): Spherical, calibrated sizes. Predictable occlusion level.
    • Mechanical Devices:
      • Coils (Platinum, Steel): Fibered or bare. Induce thrombosis, mechanical block.
      • Vascular Plugs (e.g., Amplatzer): Nitinol mesh. For larger vessels, precise.
    • Liquid Embolics:
      • N-Butyl Cyanoacrylate (NBCA/"Glue"): Rapid polymerization with ions. Mixed with Lipiodol.
      • Onyx (EVOH - Ethylene Vinyl Alcohol Copolymer): Non-adhesive, lava-like. DMSO solvent. Precipitates with blood/saline.
      • Ethanol (Absolute): Sclerosant, protein denaturation. ⚠️ High risk of non-target effects.

Classification of Embolic Agents

⭐ For effective vessel occlusion, coils should be 20-30% larger in diameter than the target vessel to ensure stable placement and prevent migration.

Clinical Embolization - Plugging Problems

  • Hemorrhage Control (Life-saving):
    • Acute GI Bleeding (e.g., peptic ulcer, diverticular)
    • Traumatic: Solid organ (spleen, liver, kidney), pelvic fractures
    • Postpartum Hemorrhage (PPH): Uterine artery embolization
    • Bronchial Artery Embolization (BAE) for massive hemoptysis
  • Tumor Management (Palliative/Adjunctive):
    • Hepatocellular Carcinoma (HCC): TACE (drug-eluting beads), TARE (Y-90)
    • Renal Cell Carcinoma (RCC), Uterine Fibroids (UFE)
    • Pre-operative devascularization of hypervascular tumors (e.g., meningiomas, JNA)
  • Vascular Anomalies & Conditions:
    • Arteriovenous Malformations (AVMs), Venous Malformations (sclerotherapy)
    • Varicocele (gonadal vein), Pelvic Congestion Syndrome (ovarian vein)
    • Pulmonary AVMs in Hereditary Hemorrhagic Telangiectasia (HHT)
  • Splenic Artery Embolization: For hypersplenism, portal hypertension (e.g., partial splenic embolization - PSE).

Angiogram: Embolization of bleeding artery with coils

⭐ Transarterial Chemoembolization (TACE) is a standard palliative treatment for unresectable Hepatocellular Carcinoma (HCC), often improving survival and quality of life by local tumor control and reducing tumor burden.

Embolization: How & Hazards - Navigating Flow

  • How: Catheter-directed delivery of agents to occlude target blood flow.
    • Access: Femoral (common), radial.
    • Guidance: Fluoroscopy, DSA.
    • Agents: Coils, particles (PVA, Gelfoam), liquids (glue, Onyx).
    • Technique: Superselective catheterization.
  • Hazards:
    • Non-target embolization (NTE) → ischemia.
    • Post-embolization syndrome (PES): Fever, pain, nausea (common, self-limiting).
    • Access site: Hematoma, pseudoaneurysm.
    • Vessel injury, contrast allergy.
  • Navigating Flow:
    • Crucial: Vascular anatomy, flow dynamics.
    • Control: Balloon occlusion, flow-directed catheters. Classification of Embolic Agents

⭐ Non-target embolization (NTE) is a critical complication; meticulous technique and anatomical knowledge are vital to prevent it.

High‑Yield Points - ⚡ Biggest Takeaways

  • Embolization treats active bleeding (trauma, GI), tumors (HCC via TACE), and uterine fibroids (UAE).
  • Agents: Gelfoam (temporary), coils & particles (permanent), glue, Onyx.
  • BAE is life-saving in massive hemoptysis.
  • PVE promotes liver remnant hypertrophy before major hepatectomy.
  • TACE combines targeted chemotherapy with ischemia for HCC.
  • Post-embolization syndrome (fever, pain) is a common, expected outcome.
  • Non-target embolization is a serious complication to avoid.

Practice Questions: Embolization Procedures

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Flashcards: Embolization Procedures

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A carotid cavernous fistula requires a definitive treatment, which currently involves the _____ technique using a balloon or coil

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A carotid cavernous fistula requires a definitive treatment, which currently involves the _____ technique using a balloon or coil

endovascular

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