1. Faculty of Medicine, Sumatera Utara University, Medan, Indonesia
2. Department of Anesthesiology and Intensive Care, Faculty of Medicine, Sumatera Utara University, Medan, Indonesia
3. Department of Internal Medicine, Division of Cardiology, Faculty of Medicine, Sumatera Utara University, Medan, Indonesia
4. Department of Obstetrics and Gynecology, Faculty of Medicine, Sumatera Utara University, Medan, Indonesia