Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post median sternotomy and CABG . A left - sided pacemaker device is again noted with leads terminating in the right atrium and right ventricle , expected locations . Cardiomegaly is stable . The mediastinal contours are stable . Low lung volumes accentuate the bronchovascular structures . There is redemonstration of increased opacities at the lung bases bilaterally , slightly more prominent on the right when compared to prior examination .
    OUTPUT:
    
Increased bibasilar opacities in the setting of low lung volumes are likely reflective of atelectasis . Evaluation for dissection is limited on chest x-ray , however mediastinal contours are stable .