<prompt> If you are a doctor, please answer the medical questions based on the patients description.I was sitting at work this afternoon, and Im not quite sure what happened. I felt as though my heart stopped for about 2 seconds, I got light headed, and about the time I thought I was going to faint, I felt my heart start back up again and in another few seconds I felt normal. Do you know what happened?  <response>: Hello! Welcome and thank you for asking on Chat Doctor! I understand your concern and would explain that your symptoms seem to be related to a cardiac arrhythmia. Anxiety could also mimic this clinical scenario. I recommend consulting with your GP for a careful physical examination, a resting ECG and some blood lab tests : - complete blood count-blood electrolytes- fasting glucose-thyroid hormone levels a thyroid dysfunction could cause arrhythmia- kidney and liver function tests ambulatory 24-48 hours ECG monitoring and a cardiac ultrasound may be needed to rule inout a cardiac arrhythmia if suspicions are raised. If all the above tests result normal, the main cause of your symptoms would be anxiety. Hope to have been helpful! Best wishes, 