Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A left pectoral pacer has leads ending in the right atrium and right ventricle . Minimal left lower lobe opacities most likely represent atelectasis ; otherwise , the lungs are clear without pulmonary edema , pleural effusions or pneumothorax . Aortic knob is calcified . The heart size is normal . There is no free air beneath the right hemidiaphragm .
    OUTPUT:
    
Pacemaker leads in appropriate position . No pneumothorax .