## Embolic Agents Classification **Key Point:** Embolic agents are classified as temporary or permanent based on their duration of effect and resorption characteristics. ### Permanent vs Temporary Embolic Agents | Agent | Type | Duration | Best Use | Mechanism | |-------|------|----------|----------|----------| | N-butyl cyanoacrylate (NBCA) | Permanent | Indefinite | High-flow AVM, fistulae | Polymerizes on contact with blood | | Polyvinyl alcohol (PVA) | Semi-permanent | Weeks to months | Tumor embolization | Mechanical occlusion | | Gelatin sponge (Gelfoam) | Temporary | 2–6 weeks | Hemostasis, temporary occlusion | Absorbable, resorbed by fibrinolysis | | Sodium tetradecyl sulfate | Sclerosant | Variable | Venous malformations, varices | Chemical thrombosis | **High-Yield:** NBCA is the gold standard for high-flow arteriovenous malformations and fistulae because it provides permanent occlusion and does not recanalize. **Clinical Pearl:** NBCA requires careful technique—it must be mixed with iodized oil or ethiodized oil to slow polymerization and allow distal penetration. Premature polymerization in the catheter is a common complication. **Mnemonic:** **PANG** — Permanent (NBCA), Absorbable (Gelfoam), Non-absorbable (PVA), Glue (NBCA again). NBCA is the "super glue" of interventional radiology. [cite:Castañeda-Zúñiga Interventional Radiology Ch 3] 
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