1. Department of Cardiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
2. Department of Emergency Internal Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
3. Department of Pediatrics, The Qingdao Central Hospital, Qingdao, Shandong 266042; 4Department of Endoscopy, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
4. Department of Endoscopy, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China