Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single frontal view of the chest was obtained . The heart is moderately enlarged . The pulmonary vasculature is unremarkable . Left lung base opacity is more prominent compared to the prior exam . The right lung is clear . No pneumothorax . Median sternotomy wires are intact . Metallic clips overlie the mediastinum . There has been interval removal of a right IJ sheath . Osseous structures are unremarkable .
    OUTPUT:
    
Increased left lung base opacity , which may represent a combination of effusion , atelectasis , or infection .