Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP single view of the chest has been obtained with patient in sitting semi-upright position . Comparison is made with the next preceding available portable chest examination of ___ . Evidence of previous thoracotomy probably related to bypass surgery similar as on previous examination . Heart size not conclusively enlarged on this portable chest examination . There is no evidence of pulmonary vascular congestion , and no acute parenchymal infiltrates can be identified . The lateral pleural sinuses are free . The drooping head obscures portions of the apical area , but there is no suspicion for any significant pneumothorax .
    OUTPUT:
    
Status post bypass surgery , but no signs of pulmonary congestion or acute infiltrates on this pre-operative chest examination .