How to manage clots in an Arteriovenous (AV) fistula to maintain its suitability for hemodialysis?

Management of AV Fistula Thrombosis While Still Functional for Hemodialysis

If your AV fistula has clots but remains usable for dialysis, proceed with urgent endovascular intervention within 24-48 hours using mechanical thrombectomy and/or pharmacologic thrombolysis combined with balloon angioplasty to treat the underlying stenosis—this approach achieves 75-94% clinical success and prevents complete access failure. 1, 2

Immediate Action Required

Timing is critical: Even though you can still dialyze, intervention must occur within 24-48 hours of detecting the clot to maximize success rates and prevent complete thrombosis. 1, 2 Delaying beyond this window significantly decreases your chances of salvaging the fistula and may force temporary catheter placement. 2

First-Line Treatment: Endovascular Intervention

Endovascular management is superior to surgery as first-line therapy according to the Society of Interventional Radiology guidelines. 1, 2 This approach includes:

Specific Techniques Used:

• Mechanical thrombectomy (suction thrombectomy, balloon thrombectomy, or clot maceration) to physically remove the clot 1, 2
• Pharmacologic thrombolysis using tissue plasminogen activator (TPA/alteplase) to dissolve remaining thrombus 1, 2, 3
• Balloon angioplasty to treat the underlying stenosis—this is the most critical step to prevent immediate re-thrombosis 1, 2
• Stent placement if needed for elastic recoil after angioplasty 1

Expected Outcomes:

• Clinical success rate: 75-94% 1, 2
• 6-month secondary patency: 62-80% 1, 2
• 6-month primary patency: 18-39% (lower, but secondary interventions maintain function) 1, 2

Critical: Address the Underlying Stenosis

90% of AV fistula thromboses are caused by anatomic stenosis from neointimal hyperplasia. 1, 2 During the thrombectomy procedure, fistulography must identify and correct this stenosis—failure to do so results in rapid re-thrombosis within days or even hours. 2, 4 The stenosis is most commonly located at the juxta-anastomotic region (near where the artery and vein connect). 5

When to Consider Surgical Consultation

Vascular surgery consultation should be obtained if: 1, 2

• Endovascular treatment fails clinically 1
• Thrombosis recurs >2 times within a single month 1, 2
• Recurrent correctable stenosis is identified in the same location 1
• Aneurysms or pseudoaneurysms are present, which contain chronic thrombus difficult to access endovascularly 1

Other Causes to Evaluate

While stenosis causes 90% of cases, also evaluate for: 1

• Hypotension after hemodialysis sessions 1
• Hypercoagulable states—consider thrombophilia testing if thrombosis is recurrent 1, 2
• Decreased cardiac output 1
• Access site infection 1

If Endovascular Treatment Fails

If declotting is unsuccessful, a tunneled cuffed dialysis catheter should be placed for temporary access (acceptable for <3 months duration) while planning for access revision or new fistula creation. 1, 2 Place the catheter in the opposite extremity to preserve vasculature for future access. 1

Common Pitfalls to Avoid

• Delaying intervention beyond 48 hours—this dramatically decreases success rates and necessitates catheter placement 2
• Failing to identify and treat the underlying stenosis during thrombectomy—this leads to immediate re-thrombosis 2, 4
• Placing multiple temporary catheters while awaiting treatment—this increases infection risk 2
• Ignoring hypercoagulable workup in patients with recurrent thrombosis (>2 episodes per month) 1, 2

Monitoring During Continued Use

While awaiting intervention, monitor for: 5

• Changes in the thrill or bruit (weakening or disappearance indicates worsening thrombosis) 5
• Prolonged bleeding after needle removal post-dialysis 5
• Arm swelling (suggests venous outflow obstruction) 5
• Complete loss of thrill—this indicates complete thrombosis requiring immediate intervention 5