Introduction
  • Acute arterial thrombosis
  • Acute and chronic venous thrombosis (including May-Thurner and thoracic outlet syndrome.

Indications
  • Acute arterial thrombosis (<14 days) with ischemia or high risk of ischemia.
  • Acute venous thrombosis (<14 days) with pulmonary embolism (PE), high risk or prior history of PE (e.g. IVC, iliofemoral) or organ failure (e.g. portal or hepatic vein thrombosis).
  • Cool, painful and deeply cyanotic limb (Phlegmasia Cerulea Dolens). 

Contraindication 
Contraindications to Pharmacologic Thrombolysis (t-PA infusion)

In the presence of a contraindication to thrombolysis, the potential risk should be evaluated against the risk of not treating the thrombosis.

  • Active hemorrhage
  • Major operation or serious trauma within 2 weeks.
  • Related to the CNS:
    1. Evidence or history of intracranial hemorrhage or suspicion of subarachnoid hemorrhage within 3 months.
    2. Recent history (within 3 months) of intracranial or intraspinal operation, serious head trauma, or stroke within 4 weeks.
    3. Lumbar puncture within 7 days.
    4. Seizures (at the onset of stroke) and uncontrolled seizures.
    5. Uncontrolled hypertension.
    6. Intracranial neoplasm, arteriovenous malformation, or aneurysm.
  • Known bleeding diathesis including but not limited to:
    1. Current use of oral anticoagulants (e.g., warfarin sodium), an International Normalized Ratio (INR) >1.7, prothrombin time (PT) > 15 (or elevated >4) seconds (Patients can receive fresh frozen plasma and then treated with thrombolytics, if indicated), or elevated activated partial thromboplastin time (aPTT) > 4 seconds.
    2. Platelet count < 100,000/mm3, despite transfusion.
    3. Renal and hepatic failure.
    4. Anti-factor Xa activity > 0.7 U/mL with recent or current unfractionated heparin.
    5. Aspirin and platelet inhibitors within 7 days.
  • Short life expectancy

Interventional Modalities for Thrombosis Management
  • Mechanical thrombolysis.
    1. Simple methods such as balloon maceration, fragmentation, pulse spray and aspiration of clot.
    2. Thrombectomy devices such as AngioJet rheolytic thrombolysis, Arrow- Trerotola, Trellis, Amplatz ClotBuster, among others.
  • Pharmacological Thrombolysis with infusion of thrombolytics via a vascular access or special infusion catheter (e.g. AngioDynamics Unifuse catheter).
  • Prophylactic IVC filter placement.
  • Combination of the above methods.

Pre-Procedure
  • Documentation of the site and extent of thrombosis with an appropriate imaging modality deemed satisfactory by the interventionalist.
  • The indications, risks and endpoints of thrombolysis should be discussed between IR, the referring service, hematology and the ICU/ICP.
  • An urgent hematology consult is initiated once the clinical indication for thrombolysis is established.

Labs
Baseline laboratory Documentation
  • CBC
  • DIC (including fibrinogen and D-dimer)
  • Kidney and liver function tests, only if known or suspected to be abnormal (not part of routine work up)

Baseline laboratory Documentation
  • The indications and contraindications are documented by both IR and the referring service.
  • Clinical signs of PE and ischemia must be documented.

An urgent ICU/ICP bed is reserved for the patient by the referring service. 
Alternatively, and based on the approval of the hematology service, the patient can be transferred to the hematology floor (6W).
The patient is kept on clear diet or NPO throughout the treatment course.

Technique
  • Appropriate consents are obtained with detailed explanation of the serious risks(e.g. severe bleeding) and expected length of treatment. The consent should include thrombolysis (mechanical and pharmacologic), balloon angioplasty and IVC filter placement.
  • The need for sedation or anesthesia is assessed on a case-by-case basis.
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  • Arteriography or venography of the affected vessel(s) is preformed.
  • If IVC filter placement is indicated, it is preferable to insert the filter prior to thrombolysis. Whenever possible, filter placement should not be performed through the affected limb.
  • The use of mechanical, pharmacologic (or combined) thrombolysis is based on the assessment of the clot burden by the interventionalist.
  • Pharmacologic thrombolysis with t-PA and heparin. Currently, tissue plasminogen activator (t-PA, Alteplase, Activase, Genentech) is the main agent for pharmacologic thrombolysis.
    1. The interventionalist or designated clinician contacts the pharmacy and informs them about the treatment plan and dose.
    2. The interventionalist orders the appropriate dose of t-PA.
    3. t-PA is prepared by the pharmacy and sent to IR.
    4. t-PA is reconstituted with normal saline (0.9% Sodium Chloride), sterile water for injection or 5% Dextrose. The standard Powerchart order set includes adding 10 mg of t-PA to 500 ml of normal saline (0.02 mg/mL) for children < 30 Kg and 20 mg of t-PA to 1000 ml of normal saline for children > 30 Kg. t-PA can be used for 12 continuous hours of infusion.
    5. The infusion rate is determined by the interventionalist based on the clinical situation and thrombus burden. An initial rate of t-PA at 0.06 mg/kg/hr is
    6. recommended with maximal initial dose of 1 mg/hr (regardless of the weight or the dose used in conjunction with mechanical thrombolysis).
    7. At the interventionalist’s discretion, a loading dose of t-PA can be used.
    8. The transcatheter infusion of t-PA is initiated in IR.
    9. The t-PA is infused via a diagnostic catheter, coaxial microcatheter, infusion catheter/wire or an IV access. The infusion site is labeled with “TPA”.
    10. The patient is then transferred to the ICU/ ICP or hematology service with proper post-op sign out to the ICU/ICP and referring service.
  • Supplemental heparin infusion:
    1. Heparin is given systematically through a separate peripheral IV access or intraarterially.
    2. The recommended sub-therapeutic dose of heparin is 10 units/kg/hr (without a loading dose) with a maximal dose of 500 units/hour regardless of weight.
  • t-PA and heparin dosages apply to both venous and arterial thromboses.

Figure

 Pre-procedural angiography showing right subclavian artery thrombus (red)
Catheter-directed thrombolysis using 3000 units of heparin and slow injection of alteplase (0.2mg/mL)
Post-procedural angiography shows minimal change in the thrombus

Complications
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Post-Procedure
Orders
The post-procedure thrombolysis plan is included in the IR list in Powerchart.
  • Continuous monitoring of the vital signs per ICU/ICP protocol for arterial thrombosis. For non-critical venous thrombosis, monitoring can be performed on the hematology floor.
  • Continuous monitoring of the affected limb for signs of underperfusion including color, temperature, perfusion, limb girth, etc.
  • ​Only essential venipunctures should be obtained while t-PA is being infused. Avoid IM injections.

Labs
  • CBC, fibrinogen and D-dimer Q 4-6 hours.
  • Maintain fibrinogen >100 mg/dL (>150 mg/dL for neonates) and platelets >100,000/μL.
  • Clot in blood bank for type and cross match.

Bleeding 
Check Q 15 min:
  • Local: Check vascular sheaths, IVs, CVLs, ETT and prior puncture sites.
  • Systemic: signs of hypotension, swelling, hematuria, GI bleeding.
  • Drop in Hgb/Hct.
  • Reduce t-PA dose by 50% if fibrinogen level falls < 100 mg/dL.

Management of major bleeding 
Associated with major hemodynamic instability or affects life-threatening organ (such as the brain and the lungs).
  1. Discontinue t-PA and heparin immediately.
  2. Resuscitate.
  3. The use of aminocaproic acid (Amicar®), cryoprecipitate, packed ped blood cells and other blood products is considered and discussed with hematology.
  4. Notify IR and hematology. If necessary, obtain appropriate consults and imaging.

Management of moderate bleeding
Profuse with no major hemodynamicinstability or involvement of life-threatening organ.
  1. If the bleeding site is accessible, start with compression (via manual or a compression device).
  2. Consider lowering the t-PA dose and/or discontinuing heparin. Discontinuing the infusion should be weighed against the risk of
  3. Notify IR and hematology. If necessary, obtain appropriate consults and imaging.

Management of minor bleeding 
Slow oozing of blood (e.g. around the vascular sheaths, from old puncture sites, mild hematuria, positive occult blood in stool, etc.)
  1. Does not constitute an indication for treatment change.
  2. Apply gentle manual or/and compression dressing around the puncture site and notify IR.

Angiographic Follow-up
  • Angiography is typically repeated Q 8-12 hours, or as ordered by the interventionalist. Follow up studies usually require no sedation or anesthesia, except if scheduled with mechanical thrombolysis or angioplasty.
  • The course of the treatment including the duration of the infusion and dose adjustment is determined based on both the clinical and angiographic findings.
  • The infusion treatment can be continued as long as reasonable progress has not been achieved or if a contraindication/severe complication occurs.​​
If further thrombolysis is no longer recommended, the sheath and catheters should be removed. Urgent CBC and coagulation studies should be obtained prior to arterial sheath removal. Arterial access may require lengthy manual pressure. Applying pressure dressing devices (e.g. Safeguard, an inflatable bulb contained within an adhesive bandage) to the puncture site can be helpful.
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