Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates low lung volumes which results in bronchovascular crowding . The heart remains stably enlarged . There is dense left basilar opacification , which may represent atelectasis or pneumonia , but is not significantly changed from prior . Median sternotomy wires and a left ventricular assist device are in place . A Swan - Ganz catheter is present with the tip ending in the right pulmonary artery , but its ifnerior loop in the right atium appears to be subluxing into the IVC . There is no pneumothorax .
    OUTPUT:
    
Stable dense left basilar opacification may represent atelectasis , however pneumonia could be considered in the appropriate clinical setting . No pulmonary edema .