Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . Heart size is mildly enlarged . Mediastinal contours are unchanged . Pulmonary vasculature is not engorged . Linear opacities are noted in the lung bases , more pronounced on left , likely reflective of atelectasis . No focal consolidation , pleural effusion or pneumothorax is seen . Degenerative changes are noted in the left glenohumeral joint .
    OUTPUT:
    
Mild bibasilar atelectasis .