Tetralogy of Fallot

 

 

Background 

 

Congenital heart defect resulting in right to left shunt, characterized by: 

  1. Large VSD 

  2. Aorta that overrides RV & LV 

  3. RVOT obstruction 

  4. Right ventricular hypertrophy 

 

 

Considerations 

 

  • Complex congenital heart disease with high risk of perioperative cardiac complications 

  • Both fixed & dynamic RVOT obstruction:

    • Fixed RVOT obstruction: variable R → L shunt & pulmonary blood flow

      • Dynamic RVOT obstruction (infundibular spasm): ↑ R to L shunting & hypoxia

  • Associated conditions: 

    • Paradoxical embolus – avoid air bubbles in lines 

    • Thrombophilia 2’ to polycythemia

    • 25% have another congenital abnormality

    • Tracheoesophageal fistula & trisomy 21

  • SBE prophylaxis

  • No AIR in IVs!

 

 

Anesthetic Goals/Conflicts

 

  • Hemodynamic goals:

    • Full preload: stiff RV, stent open RVOT

    • ↓ contractility to reduce dynamic RVOT obstruction

    • Maintain afterload to minimize R → L shunt & promote pulmonary blood flow

    • Avoid ↑ PVR (hypoxia, acidosis, aggressive PPV/PEEP) 

  • "Tet spell": sudden hypoxia/acidosis due to infundibular spasm or ↓ systemic vascular resistance (SVR): causes ↑ R → L shunt:

    • 100% O2 +/- gentle PPV

    • Fluid bolus

    • Sedation (↓ sympathetic drive): morphine 0.1mg/kg

    • Knee chest position (↑ SVR & preload)

    • Phenylephrine 5 mcg/kg, propanolol 0.1-0.3mg/kg (to ↓ infundibular spasm)

 

 

Induction Options for Patient with Unrepaired TOF Undergoing Non-cardiac Surgery

 

  • Goals are to prevent significant R → L shunt: 

    • Avoid ↑ PVR 

    • Avoid ↓ SVR 

    • Avoid myocardial depression 

    • Keep full preload 

  • Options include: 

    • Sevoflurane induction then place IV then paralyze then ETT 

    • If IV → ketamine IV (2mg/kg), then paralyze, then ETT 

    • Avoid propofol/remifentanil in these kids to prevent reduced SVR/contractility 

 

 

Repaired Tetralogy of Fallot: Most kids get definitive repair in 1st year of life 

 

  • The repair: 

    • Patch closure of the ventricular septal defect (VSD), thereby separating the pulmonary & systemic circulation

    • Enlargement of the RVOT, relieving obstructed pulmonary flow

    • RVOT enlargement is accomplished by relieving pulmonary stenosis, resecting infundibular & subinfundibular muscle bundles, &, if necessary, by a transannular patch, creating unobstructed flow from the right ventricle (RV) into the pulmonary arteries

  • Chronic problems after repair that may arise: 

    • Chronic pulmonary regurgitation 

    • Pulmonic stenosis

    • RV enlargement & dysfunction

    • Aortic root & valve dilation

    • Arrhythmias