Hypoplastic left heart syndrome

Background

Heart with hypoplastic left heart syndrome

• A congenital heart defect in which the left heart is severely underdeveloped
• Accounts for 2 to 3% of all congenital heart disease

Physiology

• With a diminutive LV, the RV must perfuse both pulmonary and systemic circulations
• Survival is dependent on:
  • PDA (for systemic perfusion from RV to the aorta)
  • Nonrestrictive ASD to ensure adequate mixing of oxygenated and deoxygenated blood

Clinical Features

Infant with cyanosis due to hypoplastic left heart syndrome.

• Asymptomatic at birth because of adequate systemic perfusion through a PDA and initially high pulmonary vascular resistance
• As the PDA begins to close and pulmonary vascular resistance decreases, may develop:
  • Hypotension
  • Acidosis
  • Respiratory distress
• Symptoms can rapidly progress from cyanosis, increased respiratory distress, and poor feeding to heart failure and cardiogenic shock

Differential Diagnosis

Congenital Heart Disease Types

• Cyanotic
  • Tetralogy of fallot
  • Total anomalous pulmonary venous return
  • Transposition of the great arteries
  • Tricuspid atresia
  • Truncus arteriosus
  • Ebstein anomaly
  • Hypoplastic left heart syndrome
• Acyanotic
  • AV canal defect
  • Atrial septal defect (ASD)
  • Ventricular septal defect (VSD)
  • Cor triatriatum
  • Patent ductus arteriosus (PDA)
  • Pulmonary/aortic stenosis
  • Coarctation of the aorta
• Differentiation by pulmonary vascularity on CXR
  • Increased pulmonary vascularity
    • Large ASD
    • Large VSD
    • Total anomalous pulmonary venous return
    • Transposition of the great arteries
    • Truncus arteriosus
  • Decreased pulmonary vascularity
    • Tetralogy of fallot
    • Rare heart diseases with pulmonic stenosis

Evaluation

• ECG
  • Right axis deviation, RV hypertrophy
• Chest x-ray
  • Cardiomegaly, increased pulmonary vasculature
• Echocardiography

Management

• Stabilize cardiopulmonary function prior to surgery
• Maintain PDA to provide sufficient mixing of oxygenated and deoxygenated blood, and adequate systemic perfusion
  • Prostaglandin E1
    • Start infusion at 0.05 mcg/kg/min IV and titrate up to 0.1 mcg/kg/min, monitoring for hypotension and apnea
    • Side Effects: Hypotension, Bradycardia, Seizures and Apnea
• Staged surgical repair
  • First stage (Norwood procedure) performed in neonates
    • SpO2 ranges in mid 70s-80s
  • Second stage (bidirectional Glenn procedure) performed at 3-6 months
    • SpO2 ranges in mid 70s-80s
  • Third stage (Fontan procedure) performed at 18-30 months
    • Preload dependent with SpO2 ranging from low to high 90s

Disposition

• Admit

See Also

• Congenital heart disease

External Links

• Animation of Norwood Procedure
• Animation of Glenn procedure
• Animation of Fontan procedure