The left retro-aortic brachiocephalic vein: morphologic data and diagnostic ultrasound in 27 cases.

A left retro-aortic brachiocephalic vein is a rare anatomic entity. A retrospective study was made of 5218 congenital cardiopathies treated between 1982 and 1998 in a medico-surgical department of paediatric cardiology. A left retro-aortic brachiocephalic vein was demonstrated in 27 patients, i.e. an incidence of 0.5%. The chief cardiopathy in these patients was a tetralogy of Fallot in 25 cases (93%). Among these 25 cases of Fallot's tetralogy the aortic arch was rightsided in 19 cases (70%). The paraclinical diagnosis of this anomaly was facilitated by ultrasonography, provided it was sought for. In this series 6 cases (22%) were discovered during surgery without previous ultrasound diagnosis. The embryological origin of the left retro-aortic brachiocephalic v. differs from that of the venous trunk in its classical anatomic form. It derives from the inferior (but not superior) transverse plexuses, connecting the two anterior cardinal veins. One of the main consequences of this anomaly is its possible confusion with other vascular structures, particularly the right pulmonary artery. Such confusion may give rise to inappropriate surgical procedures. The differential diagnosis is facilitated by the use of the Doppler: the venous flow is biphasic and regulated by respiration, whereas the Doppler recording from a pulmonary artery is that of a characteristic systolic arterial flow.