Echocardiographic diagnosis of persistent fifth aortic arch.

We describe echocardiography and computerized tomographic imaging findings in the two subtypes of fifth aortic arch in infants. In the first form, the fifth aortic arch creates a systemic to systemic connection extending from the ascending to the descending aorta. When this form appears in isolation, it does not cause hemodynamic disturbance, although associated cardiac lesions, such as aortic coarctation or interruption and patent ductus arteriosus, may influence the clinical presentation. In the second form the fifth aortic arch connects the systemic and pulmonary circulations from persistent connections between the embryological fifth and sixth arches, which may cause significant hemodynamic disturbance from left to right shunting. Although this form has been associated with a wide array of congenital cardiac lesions, this is the first description of 5th aortic arch in association with atrioventricular septal defect and double outlet right ventricle.