Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval replacement of a left pacer for a left biventricular ICD with leads terminating appropriately projecting over the left and right ventricles . The heart size is top normal . Mediastinal silhouette and hilar contours are normal . Lungs are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Appropriate positioning of left biventricular ICD without evidence of pneumothorax .