Anesthesia Considerations 

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