Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Linear atelectasis is noted in the bilateral lower lobes . A left chest wall pulse generator is in place , with pacemaker leads in the right atrium and right ventricle . Dense aortic arch calcifications are again noted . Hilar and pleural contours are unremarkable . No pneumonia , effusion , or pneumothorax is present .
    OUTPUT:
    
Bilateral lower lobe atelectasis . No evidence of pneumonia .