Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Again is seen a pacer unit in the right chest with leads terminating in the right atrium and right ventricle . Midline sternotomy wires are unchanged . A left - sided central venous catheter tip terminates in the lower SVC . The heart size is enlarged but stable . The mediastinal and hilar contours are unchanged . The lung volumes are low and bibasilar atelectasis is present , but improved . Small bilateral pleural effusions persist , larger on the right than left , but the right - sided pleural effusion has decreased . There is no pneumothorax .
    OUTPUT:
    
Improving pleural effusions and parenchymal opacities , which may reflect atelectasis ; superimposed pneumonia can not be excluded by this study , however .