Transposition of the great arteries

Transposition of the great arteries (TGA) is a form of cyanotic congenital heart disease. It is caused by the failure of the aorticopulmonary septum to spiral during septation. Children of diabetic mothers are at an increased risk of TGA.

Basic anatomical changes

• aorta leaves the right ventricle
• pulmonary trunk leaves the left ventricle

Clinical features

• cyanosis
• tachypnoea
• loud single S2
• prominent right ventricular impulse
• 'egg-on-side' appearance on chest x-ray

There is globular or ovoid appearance of the heart with apparent narrowing of the superior mediastinum (egg-on-a-string sign).

Management

• maintenance of the ductus arteriosus with prostaglandins
• surgical correction is the definite treatment.