Abstract
The aberrant right subclavian artery or the aberrant right subclavian artery syndrome is a rare anatomical variant of the right subclavian artery origin but it is the most common form of congenital anomaly of the aortic arch. The normal or abnormal appearance of the aortic arch can be explained by the regression or the persistence of one or other of the two embryonic aortic arches. The regression of the right aortic arch after the origin of the right subclavian artery will result in a normal aspect of left aortic arch with normal vascular anatomy. While the right ductus arteriosus is regressing, the left one persists. This anomaly is apparently found in the general population in approximately 0.5-1.4% of the cases and in approximately 3% of cases with congenital heart malformations. The present review is focus on the prevalence of aberrant right subclavian artery in Down syndrome. Until present it is known that ultrasound evaluation in the screening programs for Down syndrome is of uncertain value and studies on larger number of cases are reconsidered. In addition we suggest that the echocardiographic examination in the first and second trimesters should be included as a first step of the diagnosis in such congenital anomalies.