Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP single view of the chest has been obtained with patient in semi-upright position . Comparison is made with the next preceding portable chest examination obtained six and a half hours earlier during the same day . Status post sternotomy , marked cardiac enlargement and aortic valve replacement ( metallic structures of porcine valve ) unchanged . Pulmonary congestive pattern encountered earlier during the day has regressed slightly . Patient remains intubated , the ETT in unchanged position . Previously suspected small left apical pneumothorax can not be identified with certainty now on portable film and a special high contrast copy . No new pulmonary abnormalities are seen .
    OUTPUT:
    
No significant pneumothorax remaining . No new pulmonary abnormalities . Slight regression of pulmonary congestion .