Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post median sternotomy and CABG . Left - sided AICD device is re - demonstrated with leads in unchanged positions . Heart size is mildly enlarged . Mediastinal and hilar contours are unremarkable . Lung volumes are low . Pulmonary vasculature is not engorged . Patchy opacities are demonstrated in the lung bases . No pleural effusion or pneumothorax is present . Degenerative changes are noted throughout the imaged thoracic spine as well as within the imaged shoulders .
    OUTPUT:
    
Patchy opacities in the lung bases likely reflect atelectasis in the setting of low lung volumes .