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). Finally a directive is given to prevent dilator-induced vessel injuries. We report the cannulation of an unsuspected persistent LSVC in two patients. A dilator-induced vessel injury contributed significantly to the fatal outcome in the first case. On a plain chest X-ray, a catheter in a LSVC will run down the left mediastinal border and can be confused with other intravascular malpositions and extravascular malpositions. Contrast-enhanced lateral chest radiograph is an inexpensive and readily available method that can be used to determine exact position.