Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The pacer - defibrillator unit sits in the left upper chest . These are seen extending into the right atrium and right ventricle as well as into the coronary sinus and down a more distal vein , presumably to pace the left ventricle . The heart size is within normal limits and the mediastinal contours are normal . The lungs are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Pacer defibrillator unit with leads in the right atrium , right ventricle , and a distal vein of the coronary sinus .