Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest were provided . Midline sternotomy wires and prosthetic cardiac valves are redemonstrated . The heart is stable and top normal in size . There is improvement in overall pulmonary aeration with minimal lower lung atelectasis . No pneumothorax or pleural effusion is seen . Bony structures are intact .
    OUTPUT:
    
Improved aeration in the lungs with no effusion and mild bibasilar atelectasis .