What is the recommended dose of percutaneous thrombin injection for closing a dissecting pseudoaneurysm following a common femoral artery (CFA) endovascular procedure?

Percutaneous Thrombin Dosage for Femoral Artery Pseudoaneurysm Closure

For closing a dissecting pseudoaneurysm following a common femoral artery endovascular procedure, the recommended dose of percutaneous thrombin is 500-1000 international units (IU), with doses ranging from 100-2000 IU depending on pseudoaneurysm size and complexity. 1

Dosage Guidelines Based on Evidence

The ACC/AHA guidelines provide comprehensive data on thrombin dosing for femoral pseudoaneurysm closure:

• Standard dose range: 500-1000 IU for most pseudoaneurysms 1
• Extended range: 100-3000 IU, depending on pseudoaneurysm size 1
• Average dose used in clinical practice: ~435 IU (mean from multiple studies) 2

Factors Affecting Dosage

The appropriate dose depends on several key factors:

• Pseudoaneurysm size: Larger pseudoaneurysms generally require higher doses
• Complexity: Simple vs. complex (multilobed) pseudoaneurysms
  • Simple pseudoaneurysms: Average 382 IU 3
  • Complex pseudoaneurysms: Average 520 IU 3
• Neck characteristics: Pseudoaneurysms with wide, short necks require careful dosing to avoid arterial thrombosis 4

Administration Technique

For optimal outcomes and safety:

1. Use real-time ultrasound guidance for precise needle placement
2. Position a 22-gauge needle within the pseudoaneurysm cavity 2
3. Inject thrombin slowly while monitoring with color Doppler imaging
4. Observe for immediate thrombosis (typically occurs within 5 seconds) 2
5. Stop injection once flow cessation is confirmed

Efficacy and Success Rates

Thrombin injection demonstrates excellent outcomes:

• Initial success rate: 93-98% 1, 3
• Secondary success rate (after repeat injection): 99-100% 3
• Recurrence rate: Approximately 5% 1
• Recurrent pseudoaneurysms: Can be safely reinjected with high success 1

Potential Complications and Precautions

Be aware of rare but important complications:

• Distal arterial thromboembolism: Occurs in <2% of cases 1
• Allergic reactions: Rare but possible with bovine thrombin 3
• Native arterial thrombosis: Risk increases with wide, short-necked pseudoaneurysms 4

Risk Mitigation Strategies:

• Use the minimum effective dose
• Inject slowly while monitoring with real-time ultrasound
• Be particularly cautious with wide-necked pseudoaneurysms
• Have surgical backup available for potential complications

Alternative Approaches

If thrombin injection fails or is contraindicated:

• Ultrasound-guided compression therapy (though less effective and more painful) 1
• Para-aneurysmal saline injection (92% success rate in some studies) 5
• Surgical repair for failed percutaneous approaches or complicated cases 1, 6

Thrombin injection has largely replaced ultrasound-guided compression as the treatment of choice due to higher success rates, less patient discomfort, and shorter procedure times 1, 2.