Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright chest radiograph ___ at 17 : 15 is submitted .
    OUTPUT:
    
Left - sided pacer unchanged in position . The patient is status post median sternotomy with valve replacement and stable postoperative cardiac and mediastinal contours . Aorta remains tortuous and unfolded . Lung volumes remain low with crowding of the central pulmonary vasculature and evidence of mild perihilar and interstitial edema . No focal airspace consolidation to suggest pneumonia . No pneumothorax . Degenerative changes of both glenohumeral joints .