I had my followup with the doc today. He said all appears well and told me to come back in three months.

The form of SVT that I have (had?) is AV nodal reentry tachycardia. In this case, it was some tissue that was conducting the short circuit. The "burns" he did to the tissue stop it from conducting.

I've been getting my heart rate up to 190 on rides with no problems ... not bad for a 37 year old, I guess!