Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A right pectoral pacemaker with leads terminating in the right atrium and right ventricle is unchanged in position . Sternotomy wires , epicardial pacer wires and mediastinal clips are constant . The heart is mildly enlarged , which accounting for technique , is unchanged . There is central vascular congestion without overt pulmonary edema . No pleural effusion or pneumothorax . An opacity in the right low lung , only appreciated on the frontal view , could reflect atelectasis or infection . There is no rib fracture .
    OUTPUT:
    
Subtle opacity of the right lower lung could reflect atelectasis or infection , less likely contusion after trauma .