Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Rotated positioning . In addition , the patient 's chin overlies the upper mediastinum and left upper lung . Allowing for this , the patient is status post sternotomy . The heart is not enlarged . There is upper zone redistribution , without other evidence of CHF . There is increased opacity at the left lung base , not fully characterized . This may represent a combination of a small amount of pleural fluid and atelectasis . Possible hiatal hernia . Minimal atelectasis at the right lung base . The right costophrenic angle is excluded from the film , but no gross right effusion .
    OUTPUT:
    
Increased opacity at left lung base , with small pleural effusion and atelectasis . The possibility of a pneumonic infiltrate in this area can not be excluded . If clinically indicated , a lateral view may help for further assessment . Right lung grossly clear except for atelectasis at right lung base . Upper zone redistribution without other evidence of CHF . Possible hiatal hernia .