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 similar study obtained six and a half hours earlier during the same day . Status post sternotomy and cardiac enlargement with typical annuloplasty of mitral valve prosthesis as before . Patient is now extubated . Previously described right internal jugular central venous line remains in unchanged position and terminates in lower SVC . There remains a small approximately 1 cm wide pneumothorax in the right apical area . On the next preceding examination , the pneumothorax is difficult to identify . Thus , the question if pneumothorax has increased in size can not be assessed . There is no evidence of new pulmonary abnormalities . On the preceding chest examination , the patient was still intubated . The pulmonary vasculature was more prominent , but this may be related to technical image factors .
    OUTPUT:
    
Persistent small right apical pneumothorax .