Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There relatively low lung volumes . The cardiac silhouette remains markedly enlarged . The patient is status post median sternotomy and cardiac valve replacement . There is prominence of the central pulmonary vasculature suggesting mild pulmonary edema , somewhat is slightly increased as compared to the prior study . Subtle confluent opacity at the right lung base could relate to vascular congestion although an underlying consolidation is difficult to exclude . No pneumothorax is seen . There are scattered areas of linear atelectasis / scarring .
    OUTPUT:
    
Mild pulmonary edema . Cardiomegaly .