In a patient with an acutely thrombosed femoral‑popliteal bypass graft, when is catheter‑directed thrombolysis indicated and what is the recommended anticoagulation and thrombolytic regimen?

Thrombolysis in Acutely Thrombosed Femoral-Popliteal Bypass Grafts

Catheter-directed thrombolysis is indicated for acutely thrombosed femoral-popliteal bypass grafts when the limb is salvageable (Rutherford categories I, IIa, or IIb) and symptoms have been present for less than 14 days, with immediate systemic anticoagulation using unfractionated heparin as the first-line therapy. 1, 2

Immediate Anticoagulation Protocol

• Administer unfractionated heparin immediately upon diagnosis unless contraindications exist (recent major surgery, active bleeding, or spinal surgery within the past month). 1, 3, 2
• Target an activated clotting time (ACT) of 250-300 seconds during the procedure, using an initial bolus of 70 units/kg. 1
• Maintain activated partial thromboplastin time (aPTT) at 1.5-2.3 times control values for 24 hours post-procedure. 1

Indications for Catheter-Directed Thrombolysis

Thrombolysis is most effective when:

• Graft occlusion occurred within 14 days of symptom onset—this is the critical time window. 1
• The limb is salvageable (Rutherford categories I, IIa, or IIb), meaning there is no irreversible muscle damage or paralysis beyond the toes. 1, 2
• For acute bypass graft occlusions specifically, thrombolysis provides superior limb salvage at 1 year compared to surgery (enhanced limb salvage rates of 75-82%). 1, 4

Key evidence: The STILE trial demonstrated that for occlusions less than 14 days old, catheter-based thrombolysis yielded amputation rates of only 6% versus 18% for surgical therapy. 1 Beyond 14 days, surgery becomes more effective with less recurrent ischemia. 1

Absolute Contraindications to Thrombolysis

• Recent spinal surgery (within 1 month)—risk of epidural hematoma with catastrophic neurological consequences. 3
• Major surgery within 7 days—associated with 12.5% major bleeding risk versus 5.5% with surgery alone. 1, 3
• Active bleeding or recent cerebrovascular hemorrhage. 1
• Uncontrolled hypertension. 1
• Category III limb ischemia (irreversible damage with paralysis)—reperfusion causes multiorgan failure from ischemic metabolites. 2

Thrombolytic Regimen Options

Preferred agents and dosing:

• Alteplase (recombinant t-PA): 0.01 mg/kg/hour infusion directly into the thrombus via multi-sidehole catheter, associated with only 2% major bleeding rates in contemporary studies. 1
• Urokinase: 20,000 IU/min infusion rate (mean total dose 975,000 IU; range 450,000-1,300,000 IU) with 88% success rate in acute iliofemoral DVT registry. 1, 5
• Reteplase: Alternative agent with similar efficacy profile. 1

Administration technique:

• Position multi-sidehole catheter traversing the thrombus under imaging guidance. 1
• Advance catheter tip as thrombolysis progresses. 5
• Concomitant heparin infusion during thrombolysis reduces catheter-related thrombosis and graft reocclusion. 1, 5

Adjunctive Mechanical Thrombectomy

When thrombolysis is contraindicated or needs acceleration:

• Ultrasound-accelerated catheter-directed thrombolysis (EKOS system) significantly reduces thrombolysis time and total lytic agent required. 1, 6
• Pharmacomechanical or vacuum-assisted percutaneous mechanical thrombectomy achieves limb salvage rates exceeding 80% without thrombolytic hemorrhagic risks. 1, 3
• Mechanical fragmentation combined with superselective drug infusion optimizes recanalization. 1

Post-Thrombolysis Management

After successful thrombolysis:

• Identify and treat the underlying culprit lesion (stenosis, retained valve, neointimal hyperplasia) using angioplasty, stenting, patch angioplasty, or surgical revision—this is essential to prevent recurrence. 1, 4
• Continue systemic anticoagulation with warfarin or consider long-term anticoagulation for low-flow PTFE grafts. 7
• Monitor closely for compartment syndrome and reperfusion injury. 1

When to Choose Surgery Over Thrombolysis

Surgical thrombectomy or bypass is preferred when:

• Symptoms exceed 14 days duration—surgery provides better durability with less recurrent ischemia. 1
• Category IIb limb with motor deficits beyond toes—open surgical thromboembolectomy is more time-effective when motor deficits are present. 2
• Recent major surgery (within 7 days) or spinal surgery (within 1 month) makes thrombolysis too dangerous. 3
• Guidewire cannot be passed across the lesion. 1

Critical Pitfalls to Avoid

• Do not delay anticoagulation while arranging imaging or intervention—heparin prevents thrombus propagation. 2
• Do not use systemic thrombolysis—it increases major bleeding to 14% versus 4% with heparin alone, with no survival benefit over catheter-directed approaches. 1
• Do not attempt thrombolysis beyond 14 days—benefits are minimal and surgery becomes superior. 1
• Do not ignore recent spinal surgery history—this is an absolute contraindication due to epidural hematoma risk. 3
• For graft occlusion within 14 days of the primary operation, weigh thrombolysis benefits against surgical site bleeding risks carefully. 1

Expected Outcomes

• Complete recanalization rates: 40-92% depending on thrombus age and location. 1
• Limb salvage at 12 months: 82% for both thrombolysis and surgery when appropriately selected. 1
• Major bleeding with modern catheter-directed t-PA protocols: 2-4%. 1
• Recurrent ischemia is common (35-65% at 1 year) without treatment of underlying lesion. 1, 4