Tetralogy of Fallot
Background
Congenital heart defect resulting in right to left shunt, characterized by:
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Large VSD
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Aorta that overrides RV & LV
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RVOT obstruction
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Right ventricular hypertrophy
Considerations
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Complex congenital heart disease with high risk of perioperative cardiac complications
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Both fixed & dynamic RVOT obstruction:
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Fixed RVOT obstruction: variable R → L shunt & pulmonary blood flow
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Dynamic RVOT obstruction (infundibular spasm): ↑ R to L shunting & hypoxia
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Associated conditions:
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Paradoxical embolus – avoid air bubbles in lines
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Thrombophilia 2’ to polycythemia
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25% have another congenital abnormality
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Tracheoesophageal fistula & trisomy 21
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SBE prophylaxis
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No AIR in IVs!
Anesthetic Goals/Conflicts
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Hemodynamic goals:
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Full preload: stiff RV, stent open RVOT
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↓ contractility to reduce dynamic RVOT obstruction
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Maintain afterload to minimize R → L shunt & promote pulmonary blood flow
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Avoid ↑ PVR (hypoxia, acidosis, aggressive PPV/PEEP)
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"Tet spell": sudden hypoxia/acidosis due to infundibular spasm or ↓ systemic vascular resistance (SVR): causes ↑ R → L shunt:
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100% O2 +/- gentle PPV
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Fluid bolus
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Sedation (↓ sympathetic drive): morphine 0.1mg/kg
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Knee chest position (↑ SVR & preload)
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Phenylephrine 5 mcg/kg, propanolol 0.1-0.3mg/kg (to ↓ infundibular spasm)
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Induction Options for Patient with Unrepaired TOF Undergoing Non-cardiac Surgery
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Goals are to prevent significant R → L shunt:
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Avoid ↑ PVR
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Avoid ↓ SVR
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Avoid myocardial depression
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Keep full preload
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Options include:
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Sevoflurane induction then place IV then paralyze then ETT
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If IV → ketamine IV (2mg/kg), then paralyze, then ETT
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Avoid propofol/remifentanil in these kids to prevent reduced SVR/contractility
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Repaired Tetralogy of Fallot: Most kids get definitive repair in 1st year of life
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The repair:
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Patch closure of the ventricular septal defect (VSD), thereby separating the pulmonary & systemic circulation
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Enlargement of the RVOT, relieving obstructed pulmonary flow
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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
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Chronic problems after repair that may arise:
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Chronic pulmonary regurgitation
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Pulmonic stenosis
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RV enlargement & dysfunction
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Aortic root & valve dilation
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Arrhythmias
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