Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post median sternotomy and CABG . Lung volumes are low which accentuates the size of the cardiac silhouette which remains markedly enlarged . Superior mediastinal widening is also likely due to low lung volumes , and is similar compared to the prior study . There is crowding of bronchovascular structures with mild pulmonary vascular congestion . Patchy atelectasis is seen in the lung bases without focal consolidation . No large pleural effusion or pneumothorax is present . Assessment of the left apex is somewhat obscured by external device . Tracheostomy tube tip is in unchanged position .
    OUTPUT:
    
Low lung volumes with mild pulmonary vascular congestion and bibasilar atelectasis . Unchanged marked enlargement of the cardiac silhouette .