Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette is severely enlarged . The patient is status post median sternotomy . There is minor atelectasis the right lung base . No pleural effusion or pneumothorax . No evidence of pneumonia .
    OUTPUT:
    
Severely enlarged cardiac silhouette . Question pericardial effusion , cardiomegaly or left ventricular aneurysm . Alternatively , some of the perceived enlargement may be explained by the patient 's rotation and the AP projection .