Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . The heart size is normal . The mediastinal and hilar contours are unremarkable . Subsegmental atelectasis left lung base is present . The right lung is clear . No pleural effusion or pneumothorax is present . There are no acute osseous abnormalities .
    OUTPUT:
    
Subsegmental atelectasis in the left lung base .