Is heparin indicated in a thrombosed Arteriovenous (AV) fistula?

Management of Thrombosed Arteriovenous Fistula

Heparin is indicated in a thrombosed arteriovenous (AV) fistula as part of an urgent thrombectomy procedure, but not as a standalone treatment. 1

Diagnostic Approach

When an AV fistula thrombosis is suspected:

1. Immediate fistulogram is the gold standard for evaluating access dysfunction 2
   • Use non-ionic contrast material (consider 25% dilution for better visualization)
   • Assess the entire fistula conduit, venous outflow tract, and central veins
   • Look for stenosis (>50% narrowing), thrombus, aneurysms, or extravasation

Treatment Algorithm

Step 1: Urgent Intervention

• Mechanical thrombectomy or thrombolysis is the primary treatment for thrombosed AV fistulas 2
• Success rates exceed 90% with proper techniques when performed early 2
• During thrombectomy procedures, intraoperative heparin (75 units/kg IV) may be administered before clamping the artery 3

Step 2: Addressing Underlying Causes

• For stenosis: Perform percutaneous transluminal angioplasty (PTA) 2
• For resistant stenosis: Consider high-pressure balloons (25-30 atmospheres) 2
• For aneurysm with bleeding: Consider covered stent placement or surgical referral 2

Step 3: Post-Procedure Management

• Monitor the access site for bleeding
• Assess fistula function (presence of thrill and bruit)
• Evaluate distal circulation 2

Evidence Analysis

The evidence regarding standalone heparin therapy for thrombosed AV fistulas is limited:

• The American Society of Hematology guidelines focus on heparin-induced thrombocytopenia rather than primary treatment of thrombosed AV fistulas 1
• The American Heart Association guidelines do not specifically recommend systemic heparin therapy for thrombosed AV fistulas 1
• A prospective clinical study found that intraoperative administration of heparin during AV fistula surgery had no statistically significant effect on 30-day patency rates (92% vs. 86%, p=0.65) 3

Prevention of Recurrent Thrombosis

For patients at high risk of recurrent thrombosis:

• Consider combined heparin and anisodamine therapy in the immediate post-creation period (50 IU/kg heparin for 7 days), which has shown improved patency rates (96.7% vs 83.3% in controls) 4
• For abandoned thrombosed AV fistulas, especially if aneurysmatic, antiplatelet therapy should be considered to prevent distal embolization 5
• In pediatric patients, primary thromboprophylaxis with heparin followed by LMWH has shown promise in reducing early thrombosis (12.5% vs 83% in untreated patients) 6

Important Caveats

• Heparin alone is not effective for treating an already thrombosed AV fistula; mechanical or surgical intervention is required
• Timing is critical - thrombectomy should be performed as early as possible after thrombosis detection
• Open thrombectomy of AV fistulas has better outcomes than for AV grafts, with significantly improved 1-year primary patency rates (33% for upper arm fistulas vs 9% for grafts) 7
• If infection is present, broad-spectrum antibiotics (vancomycin plus an aminoglycoside) should be initiated 2

In conclusion, while heparin may be used during thrombectomy procedures and for prevention of recurrent thrombosis, it is not indicated as a standalone treatment for an already thrombosed AV fistula.