Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Minimal left pleural effusion and left lower lung atelectasis unchanged since ___ . Left upper and right lungs are clear . Mild lower lung atelectasis is similar . Normal heart size , mediastinal and hilar contours are stable . Status post median sternotomy with intact sternal sutures .
    OUTPUT:
    
Mild bibasal atelectasis and minimal left pleural effusion , stable since ___ .