Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low , which may be secondary to positioning , slightly apical lordotic angle , and inadequate inspiration . Bilateral mild to moderate interstitial edema is probably overall unchanged from the prior exam . Stable enlarged heart size . No pneumothorax . Retrocardiac opacity is probably from atelectasis , although underlying pneumonia can not be excluded . Increased opacity in the right upper lung is probably from atelectasis . Stable appearance of the left pectoral three - lead cardiac pacemaker device is again noted .
    OUTPUT:
    
1 . Stable interstitial edema and cardiomegaly . 2 . Retrocardiac opacity , likely atelectasis , but pneumonia can not be excluded in the appropriate clinical setting .