<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hello I am 30 years old and my heart will start suddelt beating rapidly for about one minute. It has happened when I suddenly raise my head quickly from a kneeling position. To straight standing. It had happened 3 Times on three weeks. I have no pain or shortness of breath.what could be wrong?  <response>: Hello! Welcome and thank you for asking on Chat Doctor! I carefully passed through your question and would explain that your symptoms could be related to a postural intolerance. I would recommend consulting with your attending physician for a careful physical exam and performing a Head Up Tilt test to exclude this possibility. Further tests are needed to exclude other metabolic causes that may trigger this symptomatology: - a complete blood count for anemia-blood electrolytes for electrolytes imbalances Hope to have been helpful! Best wishes, 