A 3-day-old male neonate born to non-consanguineous parents presents with severe cyanosis and respiratory distress. On examination, he has a single loud S2, a systolic ejection murmur at the left upper sternal border, and hepatomegaly. Chest X-ray shows an 'egg-on-string' appearance with pulmonary oligemia. Echocardiography confirms anterior aorta overriding the right ventricle with a large VSD and right ventricular outflow tract obstruction. Which of the following is the most appropriate immediate management?

Explanation

## Diagnosis Recognition **Key Point:** The clinical presentation—severe cyanosis in a neonate with 'egg-on-string' chest X-ray appearance, single loud S2, and echocardiographic findings of anterior aorta, large VSD, and RVOT obstruction—is pathognomonic for **Transposition of the Great Arteries (TGA) with VSD and pulmonary stenosis**, a variant of complex cyanotic heart disease. ### Immediate Management Strategy **High-Yield:** In cyanotic heart disease dependent on right-to-left shunting for pulmonary blood flow, the **ductus arteriosus is critical for survival**. PGE1 maintains ductal patency, allowing systemic venous return to reach the lungs via the ductus arteriosus. **Clinical Pearl:** The 'egg-on-string' appearance (narrow mediastinum with egg-shaped heart) is classic for TGA and indicates severely reduced pulmonary blood flow. Without ductal patency or an atrial communication, the infant will not survive the first hours of life. ### Why PGE1 is Correct 1. **Maintains ductus arteriosus patency** → allows pulmonary blood flow in the presence of RVOT obstruction 2. **Buys time** for definitive surgery (arterial switch operation or other repair) 3. **Improves oxygenation** by increasing pulmonary circulation 4. **Standard of care** in all duct-dependent cyanotic lesions (TGA, severe PS, critical AS, HLHS, etc.) ### Dosing & Monitoring - **PGE1 dose:** 0.05–0.1 μg/kg/min IV, titrate to effect (target SpO₂ >75%) - **Monitor for:** apnea (most common side effect), fever, hypotension, seizures - **Concurrent support:** supplemental oxygen (modest benefit in TGA), mechanical ventilation if needed, inotropes if hypotensive ```mermaid flowchart TD A[Neonate with severe cyanosis + egg-on-string CXR]:::outcome --> B{Duct-dependent lesion?}:::decision B -->|Yes| C[Start PGE1 infusion]:::action C --> D[Improve pulmonary blood flow]:::outcome D --> E[Arrange urgent echocardiography]:::action E --> F[Plan definitive surgery]:::action F --> G[Arterial switch operation or variant repair]:::action B -->|No| H[Other management pathway]:::outcome ``` **Mnemonic:** **DUCT-DEPENDENT** = **D**uctus **U**rgently **C**ritical for **T**herapy — **D**ependent lesions need **E**arly **P**rostaglandin **E1** **N**ow **D**uctus **E**xtends **N**eonatal **T**ime [cite:Nelson Textbook of Pediatrics 21e Ch 433]