Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A left pacemaker is in unchanged position with the leads in the right atrium and right ventricle . A mitral valve replacement is in unchanged position . Sternal wires are intact . The lung volumes are low . The lungs are clear without consolidation or edema . There is no pleural effusion or pneumothorax . The mediastinal contours are normal . The heart is enlarged , and appears slightly bigger than in the prior exam .
    OUTPUT:
    
1 . No acute cardiopulmonary process . 2 . Moderate cardiomegaly , possibly slightly increased from the prior exam , which could be due to an increased heart size of pericardial effusion . Alternatively , the cardiac size could be exaggerated by low lung volumes and positioning .