Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a single lead pacemaker terminating in the right ventricle . The heart appears moderately enlarged . Superior vena cava shows new mild distention . There is also a new bilateral hilar congestion . The cardiac , mediastinal and hilar contours are otherwise unchanged . Mild interstitial process suggest pulmonary edema . Left posterior basilar opacity was present before but increased .
    OUTPUT:
    
Findings suggest mild to moderate pulmonary edema . Increased left posterior basilar opacity , likely compatible with atelectasis ; it is difficult to exclude pneumonia , however .