What is the management for a pediatric patient with a history of congenital heart disease experiencing a Blalock-Taussig (BT) shunt occlusion during hemodynamic exploration?

Management of BT Shunt Occlusion During Hemodynamic Exploration

Complete BT shunt occlusion during cardiac catheterization requires immediate bolus anticoagulation with unfractionated heparin 50-100 U/kg, hemodynamic support with phenylephrine to maximize shunt perfusion pressure, and controlled ventilation to optimize oxygen delivery—this is the first-line emergency treatment per American Heart Association guidelines. 1, 2

Immediate Interventions (First-Line)

The following must be initiated simultaneously and emergently:

• Anticoagulation: Administer unfractionated heparin 50-100 U/kg IV bolus immediately 1, 2
• Hemodynamic support: Use phenylephrine (titrated to effect) to increase systemic systolic blood pressure and maximize shunt perfusion pressure 1, 2
  • Alternative: Epinephrine 10 μg/kg if phenylephrine is not immediately available 1
• Respiratory optimization: Institute controlled ventilation to maximize oxygen delivery and minimize oxygen consumption 1, 2

Escalation Strategy if Initial Measures Fail

If the above maneuvers do not immediately restore shunt patency, proceed urgently through the following hierarchy: 1, 2

Second-Line: Emergent Catheter-Based Intervention

• Mechanical thrombus removal via the existing catheter access during the ongoing hemodynamic exploration 1, 2
• Balloon angioplasty has demonstrated 84.8% early success rates and 78.8% long-lasting success 3
• Combined local thrombolytic therapy (r-tPA via catheter) with balloon angioplasty achieves 96% success rates 4
• Stent implantation may be necessary if fixed thrombus with neointimal hypertrophy is present 4

Third-Line: Emergent Surgical Thrombectomy

• Emergent sternotomy for surgical thrombectomy (milking the shunt of thrombus) if catheter-based intervention fails 1, 2

Fourth-Line: ECMO Support

• ECMO cannulation for stabilization if all above measures are unsuccessful and the patient remains critically hypoxemic 1, 2
• ECMO was required in 6 of 9 patients (67%) who needed urgent shunt intervention in one series 1

Critical Context and Risk Factors

• Complete shunt occlusion is life-threatening in patients dependent on the shunt as their sole source of pulmonary blood flow 1, 2, 5
• Shunt thrombosis occurs in 9.3% of all BT shunt patients, with 20% occurring shortly after surgery 1, 2, 5
• Younger age and lower body weight are significantly associated with procedural failure (p=0.0364 and p=0.0247 respectively) 3

Common Precipitating Factors to Address:

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

Important Caveats

• Partial shunt occlusion manifests as inability to correct hypoxemia despite increasing inspired oxygen delivery—this may precede complete occlusion 1, 2
• Heparinization at 100 U/kg is standard during catheterization to prevent femoral artery occlusion, though it has no measurable effect on coil-related occlusion rates 1
• Catheter-based interventions carry 15.2% complication rates including transient complete AV block, cardiac tamponade, and thromboembolic stroke 3
• Patients requiring early shunt intervention have significantly worse 5-year survival (41.2% vs 76.8%, p=0.002) 1