Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post recent median sternotomy and aortic valve surgery . Cardiomediastinal contours are stable in the postoperative period . Atelectasis in the left retrocardiac region has slightly improved since the previous examination . Right retrocardiac atelectasis is unchanged . Small bilateral pleural effusions are present , left greater than right .
    OUTPUT:
    
Improving left retrocardiac atelectasis . Persistent small pleural effusions , left greater than right .