Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A portable frontal chest radiograph again demonstrates a left chest pacer device with leads projecting over the right atrium and ventricle . Lung volumes are low , with bibasilar atelectasis and bronchovascular crowding . The cardiac silhouette is not well evaluated secondary to overlying opacity . There is mild pulmonary edema . Retrocardiac opacity may be due to a combination of atelectasis and edema , but superimposed pneumonia can not be excluded . There may be a small left pleural effusion . No pneumothorax is identified . The visualized upper abdomen is unremarkable .
    OUTPUT:
    
1 . Mild pulmonary edema and bibasilar atelectasis . Retrocardiac opacity . 2 . Possible small left pleural effusion .