Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: 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 can not be excluded . The right costophrenic angle is excluded , but no large right pleural effusion is demonstrated . There is no pneumothorax .
    OUTPUT:
    
Left basilar opacity may reflect atelectasis but infection is not excluded . Small left pleural effusion . Low lung volumes .