You need to see a doctor, and they will probably either:
1)Put a 24-hour heart monitor on you if it happens daily.
2)Put an event recorder on you that you can keep for up to one month to capture the fast heartrate and see what it looks like.
If you do not have any symptoms such as shortness of breath
, low blood pressure, or dizziness
during it, that's good. Still need to find out what it is.
I would see a cardiologist or electrophysiologist, who specializes in abnormal heart rhythms. They are experts in this stuff.