[Anomalous pulmonary venous connection]

An anatomical-embryological correlation of anomalous venous pulmonary connection is presented to gain an insight of its pathogenesis. The basic publications on embryonic development of the pulmonary veins were analyzed in its two stages: the primary connection of these veins (collectors) with the embryonic systemic veins from which the definitive veins arise. These channels normally disappear once the pulmonary veins sinus is connected with the roof of the left atrium (secondary definitive connection); when the latter does not exist, any of the primitive channels persist and originates the anatomic sites of the anomalous venous pulmonary connection. The embryonic systemic veins are the right cardinal (superior vena cava and azygos vein), the left cardinal (venous coronary sinus and vertical vein) and the umbilical-vitelline (portal vein and ductus venosus). Other mechanisms are discussed such as ectopic origin of the primitive pulmonary vein in the roof of the right atrium and misplaced left of the atrial septum. The atrial septal defect is conditioned by the hemodynamics of this malformation. The knowledge of the pulmonary venous development is of great value in understanding the structure and the anatomic variants of this cardiovascular malformation in its total and partial forms.