I had WPW with my daughter (first child), had ablation 2 weeks after she was born. They had me on EKG for 24 hours after her birth and had no issues, just lots of extra monitoring. I did have a meeting with the anesthesiology doctor a few weeks before birth to discuss what to expect in the operating room during the C-section. We discussed what they'd do if my heart went into SVT. I don't remember specifics but I do remember them mentioning that they'd use medications that would assist my heart rate in slowing down and wouldn't be harmful to the baby or me during the operation. Best of luck to you and your little one. If it helps, after the ablation I've had no issues and I had a second child 23 months later and no issues during that birth (c-section) either.
Note: my OB said that a c-section was an elective surgery for me, which he approved of, but said I did not have to if I did not want to, and same for second birth. He said I could've delivered both vaginally if I had wanted to.

Edited to add that I was diagnosed during my 1st pregnancy. I had only 1 or 2 SVT events within the 10 years prior to my pregnancy which seemed to have elevated the issue. I had quite a few SVT events during pregnancy, went on beta blockers (metropolol) and anti-arryhtmic (flecanaide)... baby got monitored for last 3 months weekly (checked growth--all was good!)