Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In the upper lungs are clear . Subtle bilateral retrocardiac opacities may be of clinical importance however it is difficult to correlate without prior studies and are slightly obscured by the hiatal hernia . Bowel contents are traversing the diaphragm through the hiatus and is likely due to a prior gastroesophageal surgery . Otherwise , the cardiomediastinal and hilar contours are normal . Mild blunting of the right costophrenic angle may represent a small pleural effusion or chronic scarring . The left pleural surfaces are normal . No evidence of pneumothoraces . The right pacemaker is intact with leads located in the right atrium and right ventricle .
    OUTPUT:
    
1 . Appropriate positioning of the right pacemaker leads . No evidence of pneumothorax . 2 . Bilateral retrocardiac opacities which may represent pneumonia or atelectasis . If clinical concern for infectious process , CT imaging would provide superior evaluation . 3 . A probable small right pleural effusion .