Transposition of the great arteries — branching viva

Opening question

A six-hour-old term infant is cyanosed, alert, feeding, and breathing comfortably, with a saturation of 72 per cent that does not rise on one hundred per cent oxygen and a chest X-ray showing an egg-on-a-string silhouette. What is the lesion, and why does the infant look 'comfortably blue' rather than distressed? [2] [1]

Branch 1 — securing the circulation

Take the same child. What is your immediate management, naming the drug, its starting dose range, and the airway preparation it demands? Now, an hour later, the saturation has fallen to the fifties and the lactate is climbing — what does this tell you about the mixing, and what is the next procedure, and where can it be done? [10] [1]

Branch 2 — the surgical decision

The echocardiogram confirms simple transposition with an intact septum. Name the definitive operation, state the principle that governs its timing, and explain what happens to the left ventricle if you wait too long. Now change the anatomy: add a ventricular septal defect, then add left ventricular outflow tract obstruction — how does each change the operation on offer? [4] [1]

Branch 3 — the coronary question

Why does the coronary anatomy matter so much at the arterial switch, and which coronary pattern raises the risk? What late coronary problem must you watch for in the repaired patient, and how might it first present? [4]

Closing — the atrial-switch legacy

Fast forward thirty years. A patient who had a Mustard repair presents with atrial flutter and a failing systemic ventricle. Why does this happen, why did the arterial switch replace the atrial switch, and what does this patient's future hold? [4] [1]