Plain film diagnosis in coarctation of the aorta.

The authors emphasize the importance of plain films in showing abnormalities of the aortic arch, which should permit the early radiographic diagnosis of coarctation of the aorta, before the late appearance of rib notching and cardiac enlargement. These anomalies include the elongated aortic arch, the 'figure-3' sign, the 'double indentation' sign, and the dilatation of the ascending aorta. The plain film diagnosis in newborns and infants is difficult, because of subtle or absent change of the aortic arch. Cardiomegaly with left ventricular hypertrophy may give the diagnostic clue.