Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest were provided . Midline sternotomy wires and mediastinal clips are again noted . The heart is normal in size , though stable . There is no frank edema , effusion or pneumothorax . Subtle retrocardiac opacity on the frontal projection is not substantiated on the lateral projection and could represent slight changes in ventilation . Mediastinal contour is unchanged . Bony structures are intact . A catheter is seen projecting over the left hemiabdomen .
    OUTPUT:
    
Top normal heart size without convincing signs of pneumonia or CHF .