Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest demonstrate top normal cardiomediastinal silhouette allowing for low lung volumes . There is evidence of prior coronary arterial bypass surgery . Median sternotomy wires are intact . The lungs are clear with the exception of trace atelectasis in the left base . There is no pneumothorax , vascular congestion , or pleural effusion . Dense sheet - like calcifications are seen about the abdominal aorta . There is moderate lower thoracic and lumbar spondylosis . Right glenohumeral degenerative changes seen with subchondral cystic changes .
    OUTPUT:
    
No radiographic evidence for mediastinal widening .