Transposition of the great arteries
Transposition of the great arteries or the great vessels is a cyanotic congenital heart disease characterised by the aorta arising from the right ventricle (rather than the left) and the pulmonary trunk arising from the left ventricle (rather than the right). This essentially creates two parallell circuits which are not connected. This is incompatible with life unless there is some intracardiac shunt, like patent ductus arteriosus or ventriculoseptal defect.
Diagnosis and evaluation
Echocardiography will reveal the diagnosis. Chest radiography will show the "egg on a string" sign.