Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post aortic valve prosthesis , in unchanged position . The heart size remains mildly enlarged . The mediastinal contour is unchanged . There is mild pulmonary vascular congestion and small bilateral pleural effusions , with patchy bibasilar airspace opacities appearing slightly improved in the interval . No new area of consolidation is seen . There is no pneumothorax . Multilevel degenerative changes are present within the thoracic spine .
    OUTPUT:
    
Interval improvement in mild pulmonary vascular congestion . Slight interval improvement in aeration of the lung bases likely reflective of improving atelectasis , but infection is not excluded . Small bilateral pleural effusions persist .