Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left - sided pacer is re - demonstrated with leads terminating in the right atrium and right ventricle . The patient is status post median sternotomy , aortic valve replacement , and CABG . Heart size is mildly enlarged , unchanged . Mediastinal and hilar contours are similar . Mild upper zone pulmonary vascular redistribution is likely chronic without overt pulmonary edema . Lung volumes remain low with streaky opacities in the lung bases suggestive of atelectasis . No large pleural effusion or pneumothorax is present . Fusion hardware within the lumbar spine is partially imaged as well as hardware within the right humeral head .
    OUTPUT:
    
Chronic mild pulmonary vascular congestion without overt pulmonary edema . Bibasilar atelectasis .