Congenital systemic venous return anomalies to the right atrium review

Congenital anomalies of the systemic venous return to the right atrium are rare and stem from variations in the embryogenesis of the venous system. They are usually asymptomatic, and such the major clinical significance of their recognition is to prevent misdiagnosis, in addition to some having technical implications on invasive procedures. Typically, the venous blood from the upper half of the body is carried by the right-sided, superior vena cava (SVC), and some common congenital abnormalities found are persistent left SVC, SVC duplication, anomalous drainage of the brachiocephalic veins, or interruption of the SVC. The venous blood from the lower body is carried by the right-sided, inferior vena cava (IVC), and some common congenital abnormalities found are left-sided IVC, IVC duplication, the absence of IVC (total or just the infrarenal segment), and azygos continuation of the IVC. The azygos system of veins, running up the side of the thoracic vertebral column, connects both systems and can provide an alternative path to the right atrium when either of the venae cavae is absent. Other associated azygos-hemiazygos system anomalies are the azygos lobe and variable configuration of the azygos and hemiazygos veins. Such anomalies are reviewed with particular respect to their embryology and imagiological presentation, as knowledge of the normal anatomy and the most common congenital anomalies of the systemic venous return by a radiologist is important, being incidentally found.