Mediastinal collateral arteries: important vessels in coarctation of the aorta.

Mediastinal collateral arteries are usually present in children with coarctation of the aorta or obstruction of the subclavian artery. These arteries, normally bilateral, connect the subclavian artery, costocervical trunk, or supreme intercostal artery to the descending thoracic aorta. They probably represent hypertrophied preexisting normal vessels of an embryologic origin other than persistence of a dorsal aortic root. Radiologists should be aware of the high frequency of these mediastinal vessels in patients with coarctation of the aorta and subclavian obstruction because they indicate a hemodynamically significant lesion.