1. Departments of School of Clinical Medicine, Weifang Medical University, Weifang, Shandong, China
2. Department of Gastroenterology, Peking University Third Hospital, Haidian District, Beijing, China
3. Department of Gastroenterology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
4. Department of Electrophysiology, The Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China