Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . The heart remains moderately enlarged , but unchanged . The aorta is tortuous and diffusely calcified . There is mild pulmonary vascular congestion and streaky opacities in the lung bases are likely reflective of atelectasis . Elevation of left hemidiaphragm is unchanged . Possible small left pleural effusion may be present . No pneumothorax is identified . There are mild degenerative changes in the thoracic spine .
    OUTPUT:
    
Mild pulmonary vascular congestion and mild bibasilar atelectasis . Possible trace left pleural effusion .