My eldest son (21) has SVT. He has (thankfully short!) episodes where his HR suddenly climbs up to 200 bmp (his record is 227!) for 5/10 min and then goes back to normal as suddenly as it started. There are no obvious triggers. He’s a normal weight (low BMI but he gets his body shape from his dad- tall and thin).
He had blood tests (normal) and ECGS (normal). What actually helped his diagnosis was a smart watch that had an ecg feature in addition to being able to describe his symptoms. It meant he could actually show the consultant what was going on. Obviously it wasn’t medical grade or anything and was viewed in addition to his description of symptoms.
He has these episodes completely randomly so he’s never been in a medical setting when he’s had one. He might have 3 or 4 episodes in a fortnight … then nothing for 2/3 months… then repeat.
He was told that meds (beta blockers) wouldn’t be suitable for him, because his BP and resting HR are quite low, normal but on the lower end of the scale, and as he’s incredibly tall the dose required to deal with the SVT would lower his BP too much etc… and a small enough dose not to upset his BP wouldn’t be large enough (considering his size) to help the SVT.
He was offered an ablation after electrical studies (I can’t remember the medical name but basically they thread a catheter through his groin and electrically stimulate the heart to work out where the electrical short circuit is, then they go in with a different catheter and zap the bad cells to stop the issue).
He wasn’t keen on that. There were v small but significant risks ( inducing a heart attack, and something going wrong resulting in needing a pacemaker for life) that he wasn’t happy with.
The consultant said watching and waiting was a valid option, and he could reassess at a later date. That’s what he’s decided on for now.
His episodes are awful (his description, feels like you’re about to die!) but pass very quickly and are infrequent enough that at the moment he’d rather put up with them.
Hopefully you get some answers soon OP.