You didn't state how many ectopics were recorded. Short runs of VT in a healthy person while not normal are most likely acceptable. The low rate was most likely at sleep, and the high rate was most likely during the VT episode. The isolated supra-ventricular ectopics are most likely benign and are nothing to worry about.
The stress test is to no doubt attempt to antagonize her heart to either drop into SVT or to see what else it may throw off under high stress. This is nothing to be concerned about.
My opinion: At 8 years old, your daughter is old enough to tell you that her heart feels funny, and you should encourage her to tell you of any event she may feel. Take it from someone who had their first event at 6. You can easily feel these events occur within your chest. While you shouldn't wave them off (as my mother initially did), you also shouldn't be too concerned if they are just isolated events. Sustained events, event's lasting several minutes or more should be immediately looked into.
You may want a specialists input on this. It's good though that these abnormalities havee been foundearly. The docs can help you sort this out. Some things, including some types of vt and svt are genetic, the stress test might just be the first step in getting the final diagnosis. Don't get too much about this. Not all episodes indicate a serious issue, and she could be quite healthy. It's good that you are seeing a doctor, maybe consist a specialist, but it sounds like you are headed in the right direction.
Happy to see you moved you question over here: Heart Rhythm
The above inputs are good ones, as I suspected you'd get.
Don't worry, but take measures to protect against the unexpected. It is better that you know there is an abnormality than have it be undetected. I'm sure all will work out well and while not mentioned and I think "tom_h" is an example of where it didn't, children often "outgrow" troubling health problems.
You are correct, Jerry. Despite physicians claims that I would most likely outgrow it, my arrhythmia, SVT only worsened as I aged from my first episode at six years of age to when I finally got it fixed at sixty.