What is the best initial treatment option for a patient with acute thrombosis of a Brachiocephalic (BC) or Brachial (BT) arteriovenous shunt (AV shunt)?

Acute Thrombosis of Blalock-Taussig Shunt: Emergency Management

Immediate anticoagulation with unfractionated heparin (50-100 U/kg bolus) combined with hemodynamic support (phenylephrine to increase systemic blood pressure) and controlled ventilation represents the first-line emergency treatment for acute BT shunt thrombosis. 1

Immediate Resuscitation Protocol

The American Heart Association guidelines establish a clear algorithmic approach for this life-threatening emergency 1:

First-Line Interventions (Simultaneous)

• Anticoagulation: Administer unfractionated heparin 50-100 U/kg IV bolus immediately 1, 2
• Hemodynamic support: Increase systemic systolic blood pressure with phenylephrine (titrate to effect) to maximize shunt perfusion pressure 1
• Respiratory optimization: Institute controlled ventilation to maximize oxygen delivery and minimize oxygen consumption 1

Alternative Vasopressor Option

• Epinephrine 10 μg/kg may be used if more readily available than phenylephrine 1

Escalation Strategy When Initial Measures Fail

If the above maneuvers do not immediately restore shunt patency, proceed urgently to 1:

Interventional Options (in order of preference based on available resources)

1. Emergent cardiac catheterization for mechanical thrombus removal 1, 3

   • Transcatheter intervention achieves 84.8% early procedural success and 78.8% long-lasting patency 3
   • Balloon angioplasty with or without stent placement is the primary technique 3
   • Higher failure rates occur in younger patients and those with lower body weight 3

2. Emergent sternotomy for surgical thrombectomy (to manually "milk" the shunt of thrombus) 1

3. ECMO support if the above interventions are unsuccessful and ECMO is available for stabilization 1

Alternative Thrombolytic Approach

While not the first-line recommendation in the primary guideline, systemic thrombolysis with recombinant tissue plasminogen activator has been successfully used when clinical status and resources preclude traditional rescue therapies 4. However, this should be considered only when catheterization or surgical options are not immediately available.

Critical Context and Pitfalls

Complete shunt occlusion is life-threatening in patients who depend on the shunt as their sole source of pulmonary blood flow, requiring immediate recognition and emergent management 1, 5. The American Heart Association reports that shunt thrombosis occurs in 9.3% of patients, with 20% occurring shortly after surgery 1, 5.

Common Risk Factors to Address

• Intravascular volume depletion 1
• Persistently draining pleural effusions 1
• Infection 1

Key Monitoring Points

• Partial shunt occlusion manifests as inability to correct hypoxemia with increasing inspired oxygen delivery 1
• Physical examination findings include continuous murmur (when patent), cyanosis, clubbing, and absent/diminished brachial pulse on the shunt side 5

The critical distinction: This emergency protocol differs fundamentally from chronic stenosis management, where elective interventions may be planned. Acute complete thrombosis demands immediate action within minutes to prevent death 1.