My daughter is 4 years old, healthy and very cheerful. For the past few weeks she has been saying from time to time that her heart is beating very hard. This can happen after a burst of energy or while she is watching TV or sitting quietly. I can't identify any trigger. I can feel her heart beating very hard at these times and as far as I can see it's at least 100 beats per minute, sometimes faster. It only lasts a few minutes. Her colour doesn't change and she feels fine but it startles her. She usually laughs and says "Feel this" and then I feel it pounding. We are on holiday right now; should I try to keep her particularly calm until I can get her home to a doctor? Is there anything else I should be doing?