cyclezen

+1 on that.
If you told the doc how the issue came up (under strong exercise) then he was just going thru the motions doin just an EKG. If that turned out 'normal', then he should have gone to the next step and replicate the 'conditions' that cause it in the 1st place - a stress test.
If that brings on the rapid heart beat then you;re gonna have another problem, and that is to decide what, if any, of the extreme measures the docs will prolly prescribe will be considered.
But its always better to know the score than to live with the unknown.
I'm actually surprised how many others I run into who have a similar issue, and never really talk about it.

Rule out caffeine, stay off the stuff for some days, then do your own stress test by doin your exercise routine and get the HR really up, then see if it jumps into hyperdrive. If you can't get it to sky, then maybe its caffeine related and you can make adjustments. If it still hapens, well then you can decide your next steps from there.
Let us know how things progress. I'm sure that there are a lot or BF readers who have some vested interest in hearing more on your story.
In the meantime, I'll ask Angie for more clinical detail and info on everything she went thru and how it all started. I'm a poor example in this, when it happens to me (which is most every hard ride/heavy exercise I do and have done for 30+ yrs) I just back it down enough to bring the HR back down and continue on.
Prolly not smart, but I just can;t get jacked up on every thing that goes wrong, especially somehting thatz happened so often and over such a long time span.
If I get more detail from angie, I'll post it here.

catherine96821

You could have AVNRT and need an ablation.


Sometimes, the electrical flow gets blocked or travels the same pathways repeatedly creating something of a “short circuit” that disturbs normal heart rhythms. Medicine often helps. In some cases, however, the most effective treatment is to destroy the tissue housing the short circuit. This procedure is called cardiac ablation. I had it and it totally cured me...no meds, no probs. I wanted it because it made me light headed and I do a lot of deep dives. It scared me, but turns out is was no big deal.

It isn't really dangerous and you may have had the pathway from birth. Play with your hydration status, and see if the problem lessens. I would flip into this when dehydrated and my atrial filling pressures dropped.

It is common for HRM to count "twice" if the amplitude of part of the waveform is too high.