Imaging description

Persistent left-sided superior vena cava (SVC) is the most common congenital venous anomaly of the chest. In this variant, the left-sided cava receives blood from the left subclavian and left jugular veins and courses inferiorly in the chest, lateral to the left aortic arch and hilum, and drains directly into the coronary sinus. In the vast majority of cases, a separate right-sided SVC is also present. These vessels communicate via a persistent bridging vein in 35% of patients. On chest radiograph, left-sided SVC appears as superior mediastinal widening and a right-sided venous catheter will cross the mediastinum to enter the heart on the left side. A CT will confirm the presence of left-sided SVC coursing lateral to the aortic arch and terminating in the coronary sinus (Figure 100.1). Duplicated inferior vena cava (IVC) and left-sided IVC are two congenital IVC anomalies where a left-sided IVC will be present in the left para-aortic region.

Importance

Anomalous veins can be mistaken for lymphadenopathy or masses, particularly in studies performed without intravenous contrast. The presence of anomalous veins is also important for planning of central venous access.

Typical clinical scenario

Unless the patient has congenital heart disease, these anomalies are often identified incidentally during imaging. Persistent left-sided SVC is present in 0.3% of people, with a higher incidence (4.3%) in those who have congenital heart anomalies.

Differential diagnosis

The differential diagnosis for a large venous structure coursing lateral to the ascending thoracic aorta is partial anomalous pulmonary venous return (Figure 100.2). Unlike a persistent left SVC, which courses inferiorly into the coronary sinus (Figure 100.1), this venous structure courses into the left hilum and branches into the lung parenchyma, along with the left pulmonary arteries. A central line positioned in PAPVR (partial anomalous pulmonary venous return) will course away from the mediastinum at the level of the hilum (Figure 100.2), unlike one positioned in a duplicated SVC, which extends along the heart border into the coronary sinus (Figure 100.1).