A 2-week-old full-term infant presents with mild central cyanosis, tachypnea, poor feeding, and mild hepatomegaly. Examination shows a single loud S2 and a grade 3/6 systolic ejection murmur at the left upper sternal border. Chest X-ray reveals cardiomegaly with increased pulmonary vascular markings. Echocardiography is most likely to reveal which diagnosis?

• A Tetralogy of Fallot
• B d-Transposition of the great arteries
• C Total anomalous pulmonary venous connection with obstruction
• D Truncus arteriosus ✓

Explanation

Truncus arteriosus arises from failure of division of the embryonic truncus arteriosus into the aorta and pulmonary artery, resulting in a single arterial trunk overriding a large VSD. Pulmonary overcirculation produces early heart failure with mild cyanosis, bounding pulses, and increased pulmonary vascularity on CXR. Tetralogy of Fallot classically shows decreased pulmonary vascularity. TGA presents with severe cyanosis and a narrow mediastinum. Obstructed TAPVC shows pulmonary venous congestion with oligemic lung fields and severe cyanosis disproportionate to findings.

Reference: Park's Pediatric Cardiology for Practitioners, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.