Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . Dual - lead right - sided pacemaker is seen with leads extending to the expected positions of the right atrium and right ventricle . Left retrocardiac basilar opacity is seen , which could be due to atelectasis ; however , underlying consolidation due to infection or aspiration is not excluded . There is no pleural effusion or pneumothorax . The cardiac silhouette is top normal to mildly enlarged . The aorta is somewhat tortuous .
    OUTPUT:
    
Patchy medial left basilar retrocardiac opacity is nonspecific , could be due to atelectasis , but underlying infection or aspiration not excluded .