Diagnosis of a left-sided superior vena cava during placement of a pulmonary artery catheter.

We report a case of a left sided superior vena cava (SVC) that was diagnosed during placement of a pulmonary artery (PA) catheter. After entering the left internal jugular, the PA catheter passed into the left side of the heart, through the aortic valve, and into the aorta. This was an unusual cause of right-to-left shunting and persistent cyanosis in a patient who had undergone two open cardiac procedures, including repair of an atrial septal defect. Cardiac catheterization and echocardiography also failed to reveal the abnormality. The embryology and physiology of a left sided SVC is reviewed, including an historical perspective. A discussion of the variants of the syndrome is included, as is a review of aberrant placement of central venous catheters.