Rolling Hiatal Hernia Type II

A 68-year-old multiparous woman presents with 6 months of postprandial epigastric pain, early satiety, and progressive dysphagia to solids. She has had two episodes of acute chest pain with shortness of breath after large meals. Upper GI endoscopy shows the squamocolumnar junction at the normal diaphragmatic level, but on retroflexed view, the structure marked **B** is visualized as a separate pouch with its own mucosa alongside the endoscope shaft in the posterior mediastinum. CT confirms a moderate paraesophageal hernia with 30% of the stomach in the posterior mediastinum. Which of the following best describes the pathophysiologic mechanism of her symptoms in Type II paraesophageal hiatal hernia?