How to repair a clotted and unused Arteriovenous Fistula (AVF)?

Repair of a Clotted and Unused Arteriovenous Fistula (AVF)

Endovascular intervention with mechanical thrombectomy and angioplasty is the preferred first-line treatment for a clotted and unused AVF, as it offers superior success rates (>90%) compared to surgical thrombectomy (65%) and better long-term patency outcomes. 1

Diagnostic Evaluation

Before intervention, proper evaluation is essential:

1. Physical examination: Confirm absence of pulse and thrill
2. Ultrasound assessment: Evaluate the extent of thrombosis and identify underlying stenosis
3. Fistulography: Recommended as the definitive imaging modality to guide intervention 1

Treatment Algorithm

First-Line Approach: Endovascular Intervention

1. Early intervention is critical:

   • Intervene within 24-48 hours of thrombosis detection 1
   • Delay increases risk of thrombus growth, making procedures more difficult 1
   • Early intervention increases likelihood of successful AVF salvage

2. Mechanical thrombectomy techniques:

   • Suction thrombectomy
   • Balloon thrombectomy
   • Clot maceration
   • Thromboaspiration with catheter-directed aspiration 1

3. Pharmacologic thrombolysis:

   • Can be used alone or in combination with mechanical techniques
   • Success rates of combined approaches reach >90% 1

4. Angioplasty for underlying stenosis:

   • Almost 100% of thrombosed AVFs have underlying stenosis that must be treated 1
   • High-pressure balloons (25-30 atmospheres) may be needed for resistant venous stenosis 1

5. Consider stent placement for:

   • Central vein stenosis with >50% recoil after angioplasty
   • Stenosis that recurs within 3 months 1

Second-Line Approach: Surgical Intervention

Surgical thrombectomy should be considered when:

1. Location-specific indications:

   • Forearm AVFs with juxta-anastomotic stenosis (preferred surgical approach) 1
   • Surgical technique involves Fogarty thrombectomy catheter with retrograde digital expression of thrombus 1

2. Failed endovascular therapy:

   • Consider surgical revision if thrombosis occurs >2 times within a month 1
   • May involve creation of a new anastomosis 1

3. Special situations:

   • When both artery and vein are thrombosed, conversion from side-to-side to end-to-side anastomosis can be attempted 1

Expected Outcomes

• Clinical success rates: 75-94% for thrombolysis/thrombectomy 1
• Primary patency rates: 50% at 1 year with proper intervention 1
• Secondary patency rates: 80% at 1 year 1

Important Considerations and Pitfalls

1. Timing is critical:

   • Delay increases risk of permanent AVF loss
   • Longer contact between thrombus and vessel wall increases risk of endoluminal damage 1

2. Antibiotic prophylaxis:

   • Required for any AVF intervention due to impaired immune status in dialysis patients 1

3. Post-procedure monitoring:

   • Regular surveillance for recurrent stenosis or thrombosis
   • Flow rates ≥400 mL/min at 30 days post-intervention predict successful hemodialysis function 2

4. Avoid temporary catheter use:

   • Catheter use increases mortality by 51% compared to functioning AVF 1
   • Increases risk of severe infection by 130% 1

5. Hypercoagulability testing:

   • Consider for patients with frequent or recurrent thrombotic occlusions 1

By following this algorithm, the majority of clotted AVFs can be successfully salvaged, preserving this valuable vascular access for hemodialysis and avoiding the need for temporary catheter placement, which significantly improves patient outcomes and survival.