Failure of Doppler ultrasound to detect coarctation of the aorta.

Normal velocities of flow in the aortic arch were recorded in a patient presenting with clinical signs of aortic coarctation. Angiography demonstrated complete coarctation with extensive collateral supply to the descending aorta: there was a systolic pressure difference of 40 mm Hg between the ascending and descending segments of the aorta. Despite reports of the value of Doppler ultrasound in the diagnosis of coarctation, the finding of normal velocities of flow within the aortic arch does not necessarily exclude the presence of an obstructive lesion.