Histological characteristics and classifications of coarctation of the aorta

Coarctation of the thoracic aorta is defined as a congenital narrowing of the upper part of the descending aorta, adjacent to the place of joining of ductus arteriosum or ligament, which produces a difference in the pressure above the narrowing and below it. One of the most widely accepted classifications of the coarctation is its division on the basis of the age of patients. According to this classification, coarctation is divided into the neonatal and adult type. The neonatal type of coarctation is characterized by the presence of the ductal sling and coarctational shelf placed proximally in relation to the ductal orifice. In newborn babies and younger nurslings, the shelf and neighboring parts of coarctational segment contain ductal tissue. The ductal tissue forms a 'sling' which completely surrounds the juxtaductal aorta. Clinical characteristics of the neonatal type are heart insuficiency at infancy, diffused narrowing of the aortic arch, called tubular hypoplasia, together with the wide open ductus and other congenital heart diseases. In the adult type of coarctation, the histological findings shows cystic medial necrosis. It is characterized by necrosis of smooth muscle cells, presence of cysts in the elastic lamellae filled with basophile mucopolysaccharides, followed by fibrosis with irregular fibroelastic tissue in the media. The adult type is characterized by clearly limited external narrowing of a short aorta segment in the shape of a sandglass, usually in place of the connection of ductus or ligament, or just distal. Concomitant heart diseases are rarely found in this type of coarctation.