Persistent left superior vena cava: an incidental finding during central venous catheterization-a case report.

Persistent left superior vena cava (PLSVC) is an uncommon anomaly, estimated to be present in about 0.3-0.5% of the population. It results from an embryological defect involving failure of the left cardinal vein to degenerate. It is present along with a right-sided superior vena cava in 82.2% of the cases reported. The condition most commonly occurs along with other cardiovascular malformations and frequently goes undiagnosed because when not accompanied by other anomalies it is typically asymptomatic. PLSVC is most often discovered subsequent to central venous or pulmonary artery catheter placement.