Case Background

A 2-week old infant presents to the emergency department with a 3-day history of increased respiratory rate, decreased appetite, decreased urination and pallor.

Physical examination reveals a pale, tachypneic infant with poor peripheral perfusion. Arterial pulses are equally weak in the neck and all four extremities. Heart rate is 180 bpm at rest; systolic blood pressure is 50 mmHg in the right arm; and 40 mmHg in the right leg.

Precordial examination demonstrates a sustained right ventricular impulse; single first and second heart sounds; minimal systolic murmur; and a prominent summation gallop. The liver edge is 5 cm below the right costal margin.