Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable supine view of the chest . Midline sternotomy wires and a prosthetic cardiac valve noted . There is a left chest wall pacer device with 2 leads extending to the region of the right atrium and right ventricle unchanged . The heart remains moderately mildly enlarged . Right hemidiaphragm is elevated . Mild bibasilar atelectasis noted . No signs of pneumonia or CHF . No pneumothorax . Bony structures are intact .
    OUTPUT:
    
Mild cardiomegaly . Bibasilar atelectasis .