Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A cardiac conduction device is in unchanged position . Lung volumes are low . Cardiomegaly is moderate . No definite pneumothorax . A lung base opacity seen on the lateral view may represent atelectasis , however pneumonia can not be excluded in the appropriate clinical setting . Mild vascular congestion appears to be more pronounced than on the previous study .
    OUTPUT:
    
Mild vascular congestion , new . A lung base opacity seen on the lateral view may represent atelectasis , however pneumonia can not be excluded in the appropriate clinical setting . Otherwise , no findings to explain the patient 's chest pain .