Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: ETT tip in standard position . Enteric tube traverses the diaphragm the left upper quadrant . Swan - Ganz catheter tip unchanged lying within the mediastinal contours . The patient is status post median sternotomy and cardiac valve replacement . Lung volumes remain low with bronchovascular crowding . Retrocardiac and left lower lung opacity most likely reflects a combination of atelectasis and probable small left pleural effusion . No right pleural effusion . Mild central pulmonary vascular congestion is unchanged . No pneumothorax . The heart is moderately enlarged , unchanged .
    OUTPUT:
    
Mild atelectasis and a small left pleural effusion .