Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . There are relatively low lung volumes . The patient is status post median sternotomy and cardiac valve replacement . There are areas of left greater than right bilateral mid to lower lung atelectasis . The patient is status post right thoracotomy with unchanged appearance of the surgical fracture of the posterolateral right sixth rib and blunting of the right costophrenic sulcus .
    OUTPUT:
    
Bibasilar atelectasis and post-procedural changes . No overt pulmonary edema .