Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been previous median sternotomy and coronary artery bypass surgery . Heart is upper limits of normal in size . Enlargement of the central pulmonary arteries is suggestive of pulmonary arterial hypertension . Lungs are hyperexpanded , consistent with known emphysema on prior chest CT . Additionally , there are worsening reticular opacities at the bases , which may reflect progressive interstitial fibrosis or interstitial edema superimposed upon fibrotic opacities . A more confluent opacity has developed at the left lung base , predominantly in the retrocardiac region . There are no pleural effusions . Bones are demineralized , and there has been progression in severity of a compression deformity in the mid thoracic spine on the lateral view .
    OUTPUT:
    
1 . Emphysema . 2 . Progressive basilar interstitial abnormalities , which may represent pulmonary fibrosis with or without superimposed acute interstitial edema . 3 . Confluent left basilar opacity may reflect atelectasis , pneumonia or aspiration . Followup radiographs are recommended to document resolution . 4 . Enlarged pulmonary artery suggestive of pulmonary arterial hypertension .