Hypoplastic Left Heart Syndrome

Presentation

• Cyanosis developing as the ductus arteriosus closes
• Respiratory distress and tachypnea
• Diminished peripheral pulses and poor perfusion
• Lethargy or shock in severe presentation
• Single second heart sound (S2)

Initial Workup

• Pre and post-ductal pulse oximetry
• Echocardiogram (diagnostic confirmation of diminutive left ventricle and ductal-dependent systemic circulation)
• Chest X-ray (variable, often pulmonary venous congestion)
• Arterial blood gas, serum lactate, and renal function panel

Acute Stabilization

• Initiate Prostaglandin E1 (PGE1) infusion immediately to maintain ductal patency
• Avoid supplemental oxygen to prevent excessive pulmonary blood flow (Qp:Qs imbalance)
• Provide inotropic support if ventricular dysfunction is present
• Consult pediatric cardiology and cardiothoracic surgery

Extended Pharmacology & Critical Care

• Alprostadil (PGE1) continuous infusion: Start at 0.05 to 0.1 mcg/kg/min; monitor strictly for apnea, hyperthermia, and extreme vasodilation.
• Milrinone loading dose 50 mcg/kg over 15 mins (only if stable blood pressure), followed by 0.33 to 0.75 mcg/kg/min infusion.
• Strict I&O monitoring; maintain urine output > 1-2 mL/kg/hr using indwelling catheter if necessary.
• Maintain hematocrit > 35-40% via PRBC administration to optimize oxygen delivery in cyanotic lesions.
• Nursing: Q1 hour blood pressure monitoring (arterial line preferred), monitor for feeding intolerance indicating gut hypoperfusion.

Standardized Discharge & Follow-Up Criteria

• Adequate weight gain explicitly > 15-30g/day over a continuous 3-5 day period.
• Maintenance of temperature in an open crib with standard clothing for 48 hours.
• Successful completion of the 90-120 minute Infant Car Seat Challenge.
• Caregiver successfully completed CPR training, rooming-in, and independent medication administration.
• Referrals placed for High-Risk Infant Follow-Up Clinic, Early Intervention (PT/OT), and appropriate sub-specialists.

Diagnostic & Management Algorithm

• HLHS Pre-op Stabilization: [START] PGE1 Infusion Active -> [DECISION] SpO2 < 75%? -> [YES] Increase FiO2/Ventilate -> [DECISION] SpO2 > 85%? -> [YES] Add FiCO2 / decrease FiO2 to balance circulation -> [GOAL] Norwood Procedure

References

1. Barron DJ, Kilby MD, Davies B, et al. Hypoplastic left heart syndrome. Lancet.
2. Feinstein JA, Benson DW, Dubin AM, et al. Hypoplastic left heart syndrome: current considerations and expectations. J Am Coll Cardiol.