Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . Heart size is normal . The aorta remains tortuous . Pulmonary vascularity is not congested . Linear opacities in the left lung base likely reflect subsegmental atelectasis . No focal consolidation , pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities . Mild degenerative changes are seen in the imaged thoracolumbar spine .
    OUTPUT:
    
Subsegmental atelectasis in the left lung base . Otherwise no acute cardiopulmonary abnormality .