Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post sternotomy . The heart is at the upper limits of normal size . There is moderate unfolding of the thoracic aorta . The lungs appear clear . There are no pleural effusions or pneumothorax . Mild degenerative changes involve the lower thoracic spine .
    OUTPUT:
    
No evidence of acute disease .