Introduction |
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Indications |
Embolization is indicated for GI bleeding that does not respond to conservative measures such as fluid resuscitation, correction of coagulopathy, and administration of blood products. Specific indications include:
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Contraindications |
There are no absolute contraindications.
Relative contraindications include:
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Equipment Used |
The following equipment is commonly employed in GI bleed embolization:
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Pre-procedural evaluation |
Before proceeding with embolization, a thorough evaluation is essential:
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Patient with history of lupus presenting with GI bleed. CT-angiography shows active extravasation of intravascular contrast into small bowel lumen involving distal jejunum/proximal ileum of the left mid-abdomen.
Procedure
Preparation and Patient Evaluation
Diagnostic Arteriography
Embolization
- Preprocedural Imaging: Confirm the bleeding site using Tc-99m RBC scans or angiography.
- Sterile Setup: Ensure a sterile field, with all necessary equipment within reach.
- Anesthesia: General anesthesia is preferred, especially in younger children, to minimize movement and ensure cooperation.
- Vascular Access: Gain vascular access via the common femoral artery using ultrasound guidance. A 4 to 5 French arterial sheath is typically placed.
Diagnostic Arteriography
- Fluoroscopic Setup:
- Position the patient under fluoroscopy and ensure the imaging equipment is calibrated for optimal visualization.
- Initial aortography may be performed to provide a broad overview of the visceral vascular anatomy but can be bypassed if there is a concern for contrast limit.
- Selective Angiography:
- Begin with selective catheterization of the suspected bleeding vessel based on clinical, endoscopic, and imaging data.
- For upper GI bleeding (hematemesis, melena), catheterize the celiac artery first, followed by the superior mesenteric artery (SMA).
- For lower GI bleeding (bright red blood PR), catheterize both the SMA and the inferior mesenteric artery (IMA).
- Use an angled catheter (e.g., Cobra, Sos Omni) for difficult vessel origins.
- Assessment of Bowel Peristalsis:
- Perform brief fluoroscopy of the abdomen to evaluate the extent of bowel peristalsis.
- If peristalsis is substantial, administer intravenous glucagon to inhibit motion and reduce artifacts during digital subtraction angiography (DSA).
- Visualization of Bleeding:
- Inject contrast media through the catheter to identify active extravasation (intraluminal contrast) or stasis of contrast.
- Identify and confirm the bleeding source by observing for contrast leakage into the GI lumen.
- Consider provocative angiography (use of anticoagulants, vasodilators) if bleeding is suspected but not immediately visible.
- Note: Tortuous small arteries or ileal branches may extend to the antimesenteric border in Meckel’s diverticulum.
- If vasospasm, consider nitroglycerine in 1-2 μg/kg aliquots.
Embolization
- Catheter Positioning:
- Ensure the catheter tip is positioned safely within the bleeding vessel, close to the site of extravasation, but without causing vessel injury.
- Use super-selective catheterization techniques for precise targeting, especially in small or tortuous vessels, while assessing the collateral flow.
- Vasopressin infusion:
- Consider vasopressin infusion when the hemorrhage site is inaccessible with a microcatheter or if the bleeding involves a more diffuse area.
- Administer at a rate of 0.1–0.4 units/minute, with gradual tapering to avoid rebound bleeding.
- Embolic Agent Selection:
- Select embolic agents based on the type of bleeding, vessel size, and desired outcome.
- Temporary Agents: Gelfoam slurry (mixed with contrast and saline) is preferred for initial control, especially in cases where temporary hemostasis is acceptable.
- Permanent Agents: PVA particles (minimum size 300 μm), microcoils (detachable coils), or glue (Histoacryl or nBCA) may be used for more definitive control. PVA particles are particularly effective for occluding small vessels.
- Embolic Agent Preparation:
- Mix the embolic particles (e.g., PVA, Embospheres®) with contrast media (typically a 1:1 ratio) to allow real-time visualization during injection.
- Prepare coils or liquid agents (e.g., nBCA) according to manufacturer instructions, ensuring sterility and readiness.
- Embolic Material Delivery:
- Inject embolic particles using a controlled, pulsatile technique under fluoroscopic guidance, observing the flow and distribution within the vessel.
- Coil Embolization:
- Deploy coils into the vessel in a proximal-to-distal manner to achieve segmental occlusion, ensuring both proximal and distal sites are secured ("bridging technique").
- Consider "sandwich" embolization (occluding both sides of the bleeding point) to prevent rebleeding through collateral circulation.
- Liquid Embolic Agents:
- Carefully deliver liquid agents like nBCA using microcatheters to avoid non-target embolization. These are typically used for high-flow lesions.
- Monitoring During Embolization:
- Continuously monitor the patient's hemodynamic status and adjust the procedure as needed to avoid complications such as hypotension or ischemia.
- If necessary, use balloon occlusion to control high-flow vessels during embolic agent delivery.
- Completion of Embolization:
- Once satisfactory occlusion is confirmed, withdraw the catheter carefully while maintaining hemostasis at the access site.
- Perform a post-embolization angiogram to verify the cessation of bleeding and ensure no residual flow to the treated area.
Angiography
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1. SMA – Focal extravasation from vasa recta branch of the SMA
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2. Selective ileal branch arteriogram: Active extravasation seen, with likely small aneurysm.
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Selective DSA image demonstrating the site of active extravasation.
3. Post-embolization SMA: No evidence of extravasation following embolization with PVA particles.
Post-Procedure Care |
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Complications |
Potential complications of GI bleed embolization include:
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References |
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