Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest . Sternotomy wires are unchanged . The cardiomediastinal hilar contours are normal . Moderate hiatal hernia is seen . Mitral valve replacement is seen . Subtle opacity in the lower lungs seen on lateral view is likely a confluence of shadows . There is no focal consolidation , pleural effusion or pneumothorax . Mild increase in interstitial opacities may represent mild interstitial pulmonary edema .
    OUTPUT:
    
Mild increase in interstitial opacities may represent mild interstitial pulmonary edema .