This 75 year old female patient presents with a history of gastrointestinal reflux dysphasia (GERD).
Note the very large air fluid level seen through the heart on the frontal images, and in the retrocardiac space just posterior to the left ventricle. This large air bubble represents the fundus of the stomach (Magenblasse). This patient has approximately two-thirds of their stomach in their thorax and represents a huge sliding hiatal hernia.
A frequent symptom of hiatal hernia is acid reflux to the esophagus. This patient is likely sleeping with two or three pillows elevating their head. Not all sliding hiatal hernias are symptomatic but one this size certainly was. Follow up with a gastroenterologist is recommended.