Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Pacer unit projects over the left chest with leads in the right atrium and right ventricle . The heart is large , but stable . Mediastinal contours demonstrate calcified atherosclerotic disease of the aortic knob and a mildly tortuous aorta . The lungs are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Stable cardiomegaly , but no acute cardiopulmonary process .