Structural Heart Disease, Cyanotic

Key Features

• Cyanosis, initially without associated respiratory distress

• Failure to increase PaO₂ with supplemental oxygen

• Causes

  • Transposition of the great vessels

  • Total anomalous pulmonary venous return

  • Truncus arteriosus (some types)

  • Tricuspid atresia

  • Pulmonary atresia

  • Critical pulmonary stenosis

Clinical Findings

• Hallmark of many of these lesions is cyanosis without associated respiratory distress

• In most of these infants, tachypnea develops over time either

Diagnosis

• Comparing the blood gas or oxygen saturation in room air to that in 100% FIO₂ can be helpful

  • Failure of PaO₂ or SaO₂ to increase suggests cyanotic heart disease

  • Note: A PaO₂, if feasible, is the preferred measure

  • Saturation in the newborn may be misleadingly high despite pathologically low PaO₂ due to the left-shifted oxyhemoglobin dissociation curve seen with fetal hemoglobin

• Many cases are diagnosed antenatally by ultrasound

• Chest radiograph with decreased lung markings suggests right heart obstruction, while increased lung markings suggest transposition or pulmonary venous obstruction

• Chest radiograph typically shows a small to normal heart size with marked pulmonary edema

• Infants with right-sided heart obstruction (pulmonary and tricuspid atresia, critical pulmonary stenosis, and some forms of truncus arteriosus) have decreased lung markings on chest radiographs and, depending on the severity of hypoxia, may develop metabolic acidemia

• Those lesions with an underdeveloped right-sided heart will have left-sided predominance on electrocardiography

• Echocardiography confirms diagnosis

Treatment

• Early stabilization includes supportive therapy as needed (eg, intravenous glucose, oxygen, ventilation for respiratory failure, and vasopressor support)

• Specific therapy includes infusions of prostaglandin E₁ (0.0125–0.025 μg/kg/min) to maintain ductal patency