Tetralogy of Fallot Repair (Infant)
Patient phenotype
Infant 3-12 months, cyanotic congenital heart disease. Four lesions: VSD, overriding aorta, pulmonary stenosis (RVOTO), RVH. Hypercyanotic 'tet spells' on history. Cardiology + surgery jointly managed.
Procedure
Median sternotomy + cardiopulmonary bypass + cardioplegia. Surgical: close VSD, relieve RVOTO (transannular patch or RV-PA conduit). 4-6 hours. Outcome: corrected anatomy, but lifetime cardiology follow-up.
Anesthetic plan
GETA, low-dose volatile + opioid + low-dose ketamine (preserves SVR + helps tet physiology), maintain hydration, avoid factors that worsen R→L shunt.
Setup
- ·Pediatric ASA monitors + temp + Foley + NIRS
- ·Pre-induction A-line (small; under deep sedation if needed)
- ·Central line (small bore, RIJ or femoral)
- ·Echo / TEE (mini-probe for infant)
- ·Heparin + protamine + ACT
- ·Inotropes drawn pediatric concentrations: epi 0.1 mcg/kg/min, milrinone, dobutamine
- ·Cell saver
- ·Phenylephrine for tet spell rescue
Biggest concerns by phase
Tet physiology — what worsens the R→L shunt
Worsens shunt + cyanosis: ↓SVR (vasodilators, hypotension), ↑PVR (hypoxia, hypercarbia, acidosis, sympathetic stim from light anesthesia), ↑RVOT spasm (catecholamines). Hypercyanotic 'tet spells' = sudden severe desat from any of these.
Induction technique — preserve SVR
Ketamine 1-2 mg/kg IM (or IV if access) is classic — maintains/raises SVR. Sevo + N₂O alternative if airway secure. Avoid deep propofol bolus (drops SVR). Phenylephrine drawn for any drop.
Tet spell — recognize + treat
Sudden severe cyanosis from RVOT spasm + R→L shunt increase. Treatment cascade: 100% O₂, knee-chest position (in awake infant), volume bolus, phenylephrine 5-10 mcg/kg (raise SVR, push blood to lungs), morphine 0.1 mg/kg (sympatholysis), propranolol 0.1 mg/kg IV (RV outflow relaxation), bicarb if acidotic.
CPB physiology in pediatric — tiny volumes, big shifts
Infant blood volume ~80 mL/kg → 4 kg infant = 320 mL total. Pump prime 200-400 mL = significant hemodilution. Modified ultrafiltration post-bypass concentrates RBCs + clotting factors. ACT > 480 sec target as in adult. Heparin 300-400 U/kg.
Coming off bypass — RV management
Right heart often dysfunctional after VSD closure + RVOT relief (the chronic RVH adapted to pre-op anatomy now overdone). Inotropes: milrinone (RV inotropy + pulmonary vasodilation), epi for systemic + RV support. iNO 20 ppm for pulmonary vasodilation. Avoid hypoxia/hypercarbia (raise PVR).
ICU intubated — junctional ectopic tachycardia + RV failure
Direct to PCICU intubated. Watch: junctional ectopic tachycardia (JET, common after VSD closure — treat with amiodarone, cooling, pacing), RV failure (rising CVP, low CO, hepatomegaly), residual shunts (echo POD 1).
Mock-defense scenarios
Practice answering these out loud. The probes show what an examiner is listening for.
9-month-old TOF infant in OR for repair. Pre-bypass induction complete. As you place the central line, SpO₂ suddenly drops from 88% to 65%, HR rises to 200. Surgeon hasn't started yet. What's happening and what do you do?
What an examiner probes for
- ▹Recognizes tet spell — RVOT spasm + worsening R→L shunt
- ▹100% O₂, deepen anesthetic (ketamine or fentanyl) to reduce sympathetic stim
- ▹Knee-chest position not feasible (lying flat) — alternatives: phenylephrine 5-10 mcg/kg
- ▹Volume bolus + phenylephrine to raise SVR
- ▹Propranolol 0.1 mg/kg IV if persistent
- ▹Bicarb if acidemia developing
Sources
- Pediatric Cardiac Anesthesia (Andropoulos)
- Lake Cardiac Anesthesia for Congenital Heart Disease
Anatomy reference
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