Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Dual lead left - sided pacer device is stable in position . The patient is status post median sternotomy and cardiac valve replacement . The cardiac and mediastinal silhouettes are stable . There are lower lung volumes on the current study than on the prior . There is blunting of the posterior left costophrenic angle concerning for a left pleural effusion . No right pleural effusion is seen . Left base retrocardiac opacity may be represent combination of pleural effusion and atelectasis , however , underlying consolidation is difficult to exclude . While there may be minimal central pulmonary vascular engorgement , no overt pulmonary edema is seen .
    OUTPUT:
    
Left pleural effusion . Low lung volumes with possible minimal central pulmonary vascular engorgement . No overt pulmonary edema .