One more reason that it would be worthwhile to have this evaluated: a family history can be reviewed, which can be important in certain cases of arrhythmias, especially those that could be more dangerous..
Dear Bonz,
Rapid heart beats are typically either a normal heart beat or an abnormal heart beat (arrhythmia). From just this history, I cannot tell exactly what your daughter is experiencing. Even if it is happening once a month, it still could be an arrhythmia. There are some arrhythmias that, though they are abnormal, are a nuisance. But, there are also some arrhythmias that are both abnormal and dangerous. Therefore, I do think that it would be worthwhile to get these palpitations evaluated. An ECG can be obtained, which can look for a risk for underlying rhythm abnormalities. Also, there are monitors that can be worn for one month at a time that record the heart rate during specific events, such as when your daughter has her palpitations. These can be evaluated to make sure that these are benign. Something that you can do in the meantime is to try to count how many beats are occurring in one minute; the best way to do this is to count how many beats happen in 6 seconds and multiply by 10. If there are more than 180 beats per minute at rest for no good reason, then this is most likely an arrhythmia.
Finally, if your daughter has persistent palpitations for more than 20 minutes, or has associated dizziness, passing out, or chest pain, she should be seen at your local emergency department.