FINDINGS:
There is a large right-sided pleural effusion, mildly increased. 
 The patient is status post coronary artery bypass graft surgery and aortic
 valve replacement.  Parenchymal opacity in the right lung could be explained
 as associated atelectasis.  There is no clear evidence for parenchymal edema. 
 The left lung remains clear, without left-sided pleural effusion, aside from
 streaky opacities suggesting mild fluid in the major fissure.

IMPRESSION:
Increasing large right-sided pleural effusion.  If the etiology
 is uncertain, then chest CT, preferably with intravenous contrast if feasible,
 is suggested when clinically appropriate to evaluate for the potential cause.