Complete interruption of the aortic arch. 1. Characteristic radiographic findings in 21 patients.

The radiographs of 21 patients with complete interruption of the aortic arch are reviewed, together with the literature, to emphasize characteristic radiographic features previously not recognized or discussed. In addition to the nonspecific radiologic findings of a left-to-right shunt through the invariably present ventricular septal defect, charateristic and unique features noted on chest radiograph and barium swallow that may suggest the diagnosis prior to catheterization include: a) a midline trachea; b) a hypoplastic ascending aorta with direct vertical ascent toward the neck; c) absence of the aortic "knob;" d) termination of the descending thoracic aortic shadow at the level of the main pulmonary artery; e) a "low arch" on lateral or left anterior oblique projections; and f) absence of the normal aortic impression on the barium-filled esophagus. Rib notching, when present, in association with the above findings indicates a stenotic or closed ductus arteriosus with collateral circulation through intercostal arteries to the descending aorta. The bilateral or unilateral location, right or left side, of the notching is dependent on the site of interruption and origin of the subclavian arteries and may permit differentiation into types and subtypes on chest radiograph.