Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . Heart size is moderately enlarged and is accentuated due to low lung volumes . The mediastinal and hilar contours are unremarkable . There is crowding of the bronchovascular structures , but no overt pulmonary edema . No focal consolidation , pleural effusion or pneumothorax is seen . Minimal atelectasis is noted in the lung bases . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes . Mild bibasilar atelectasis .