Pediatrics · Year 3 · from Pediatrics

Case 1: Congenital Heart Disease - Hypoplastic Left Heart Syndrome

Patient Demographics

  • Age: 3-day-old male
  • Sex: Male

Chief Complaint

"The baby is breathing fast and looks gray."

History of Present Illness

A 3-day-old male infant, born at 39 weeks gestation via uncomplicated vaginal delivery, is brought to the emergency department by his parents. He was discharged home at 48 hours of life and was initially breastfeeding well. Over the past 12 hours, he has become increasingly difficult to feed, seems to tire quickly at the breast, and is breathing faster. His parents noticed his skin has a grayish color, and he feels cool to the touch. The pregnancy was uncomplicated, and no prenatal ultrasound abnormalities were noted. Newborn screening and pulse oximetry at discharge were reportedly normal.

Physical Examination

  • Vital Signs: Temperature 36.2C (hypothermic), HR 170 bpm, RR 68/min, BP 55/35 mmHg (right arm), SpO2 78% on room air
  • General: Lethargic, gray-appearing infant in respiratory distress
  • Skin: Mottled, cool extremities, delayed capillary refill (4 seconds)
  • Cardiovascular: Tachycardic, weak peripheral pulses, no murmur audible, single S2
  • Respiratory: Tachypneic with nasal flaring and subcostal retractions; lungs clear
  • Abdomen: Liver edge palpable 3 cm below costal margin (hepatomegaly)
  • Neurologic: Decreased activity, weak cry

Laboratory and Imaging Findings

  • Blood gas: pH 7.18, pCO2 28, pO2 35, HCO3 10 (severe metabolic acidosis)
  • Lactate: 9.2 mmol/L (markedly elevated)
  • Glucose: 45 mg/dL
  • Chest X-ray: Cardiomegaly with pulmonary venous congestion
  • Echocardiogram: Hypoplastic left ventricle, mitral atresia, aortic atresia, hypoplastic ascending aorta, patent ductus arteriosus with right-to-left flow providing systemic circulation

Diagnosis

Hypoplastic left heart syndrome with closing ductus arteriosus

Clinical Reasoning

This infant presents with shock at day 3 of life, the classic timing for ductal-dependent systemic blood flow lesions. In hypoplastic left heart syndrome (HLHS), the left ventricle, mitral valve, and aortic valve are severely underdeveloped, making systemic circulation entirely dependent on the patent ductus arteriosus (PDA) to deliver blood from the right ventricle through the pulmonary artery to the aorta. As the ductus closes physiologically in the first days of life, systemic perfusion decreases catastrophically, resulting in shock, metabolic acidosis, and end-organ dysfunction. The gray color, weak pulses, hepatomegaly, and lactic acidosis all reflect systemic hypoperfusion. This is a medical emergency requiring immediate prostaglandin E1.

Management

  1. Prostaglandin E1 (PGE1): Start IMMEDIATELY at 0.05-0.1 mcg/kg/min IV to reopen the ductus arteriosus
  2. Prepare for apnea: PGE1 side effect; have respiratory support ready, may require intubation
  3. Fluid resuscitation: 10 mL/kg normal saline bolus (cautious volume in cardiac disease)
  4. Correct acidosis: Sodium bicarbonate if severe acidosis persists after PDA opens
  5. Glucose: Correct hypoglycemia with D10W bolus (2 mL/kg)
  6. Avoid oxygen: Keep saturations in 70s-80s; excess oxygen causes pulmonary vasodilation and worsens systemic steal
  7. Cardiology/cardiac surgery consultation: Urgent; plan for staged surgical repair (Norwood procedure)
  8. Transfer to cardiac center: ICU at a pediatric cardiac surgery center

Clinical Image

Image Description: Echocardiogram demonstrating hypoplastic left heart syndrome with a severely underdeveloped left ventricle, illustrating the anatomical basis for ductal-dependent systemic circulation.

Source: Radiopaedia URL: https://radiopaedia.org/cases/hypoplastic-left-heart-syndrome-1 License: CC BY-NC-SA 3.0

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