Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left - sided AICD / pacemaker device is noted with intact leads in the right atrium and right ventricle . The patient is status post median sternotomy and CABG . Heart size is mildly enlarged , though probably accentuated due to the presence of low lung volumes . There is crowding of the bronchovascular structures but no overt pulmonary edema is seen . Patchy opacities in the lung bases are similar compared to the prior exam , likely reflecting atelectasis in the setting of low lung volumes . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes with probable bibasilar atelectasis . Pacing leads in unchanged positions and appear intact .