Main types of coarctation of the aorta
Coarctation of the aorta is a focal flow-limiting narrowing of the aorta which can be either preductal (located upstream from the ductus arteriosus) or postductal (located downstream from the ductus arteriosus). In preductal coarctation, blood flow to the distal aorta is dependent on a patent ductus arteriosus and can therefore be life-threatening when the ductus arteriosus closes. Preductal coarctation is associated with Turner’s syndrome. Postductal (adult) coarctation usually presents in older children or adults with differential blood pressures noted, greater in the upper extremities compared to the lower extremities. Blood flow to the aorta distal to the coarctation may occur through intercostal arteries, creating inferior rib notching on chest radiograph. Sometimes, a “figure 3” sign may be seen on the frontal chest radiograph, where the upper left mediastinal contour has a bilobed configuration due to dilation of the aortic arch and left subclavian artery upstream to the site of coarctation, focal indentation of the aorta at the site of coarctation, and poststenotic dilation of the descending thoracic aorta.