Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiograph demonstrates clear lungs without effusion or pneumothorax . The heart size is top normal . Surgical clips and median sternotomy wires are seen status post CABG . Note is made of calcification of the aortic arch . On the lateral view , a retrocardiac structure which appears calcified may represent a calcified lymph node .
    OUTPUT:
    
1 . Top normal heart size , without acute chest pathology . 2 . Calcified structure seen posterior to the heart on the lateral view might represent a calcified lymph node .