Pathophysiology
Clinical meaning
Coarctation of the aorta (CoA) is a congenital cardiovascular malformation characterized by a discrete narrowing (stenosis) of the thoracic aorta, most commonly located in the juxtaductal region -- just distal to the origin of the left subclavian artery at the site where the ductus arteriosus (ligamentum arteriosum after closure) inserts into the aortic isthmus. This anatomical localization is not coincidental: the ductal tissue theory proposes that ectopic ductal smooth muscle tissue extends into the aortic wall, and when the ductus arteriosus constricts during normal postnatal closure, this aberrant ductal tissue within the aortic wall also constricts, producing a localized shelf-like narrowing of the aortic lumen. CoA occurs in approximately 5-8% of all congenital heart defects, with an incidence of approximately 4 per 10,000 live births, and has a male predominance of approximately 2:1. It is strongly associated with Turner syndrome (45,X) -- CoA is present in 10-15% of patients with Turner syndrome, and all females with CoA should be evaluated for Turner syndrome with karyotype analysis. CoA frequently coexists with other cardiac anomalies, most notably bicuspid aortic valve (present in...