Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear . The cardiac silhouette is mildly enlarged . The aortic knob is visualized . No upper mediastinal widening . No pulmonary edema are pneumonia . Prior median sternotomy with intact sternal wires and dual lead defibrillator with the tips in the right atrium and right ventricle .
    OUTPUT:
    
No acute cardiopulmonary process . No radiographic evidence of dissection .