Incidental discovery of a partial anomalous pulmonary venous connection in the surgical critical care unit.

Routine chest roentgenogram to confirm catheter placement in a postsurgical patient showed a left-sided internal jugular central venous catheter that did not appear to cross the midline. Arterial blood gas samples showed greater oxygenation from the central catheter as compared with the peripheral arterial sample. However, a transduced waveform showed a venous tracing and pressure. Computed tomographic scan of the thorax without intravenous contrast showed a partial anomalous pulmonary venous connection with drainage of the left upper lobe pulmonary vein into the innominate vein.