Persistent left superior vena cava: clinical implications for central venous cannulation.

In general, persistence of the left superior vena cava (LSVC), the most common anomaly of the venous circulation, is asymptomatic. Diagnosis of a catheter in a persistent LSVC is not straight forward, and a LSVC can create difficulties during central venous and pulmonary artery catheterization. We discuss the differential diagnosis of left-sided central venous catheters (CVC).