FINDINGS:
The patient is status post median sternotomy and CABG.  The heart remains
 moderately enlarged.  Aortic knob calcifications are again seen.  Low lung
 volumes are present with crowding of the bronchovascular structures.  There is
 no overt pulmonary edema, with a small left pleural effusion likely present. 
 Retrocardiac opacity may reflect atelectasis.  Infection cannot be excluded. 
 The right costophrenic angle is excluded, but no large right pleural effusion
 is demonstrated.  There is no pneumothorax.

IMPRESSION:
Left basilar opacity may reflect atelectasis but infection is not excluded. 
 Small left pleural effusion.  Low lung volumes.