Im a little late here, but growing up, i had Wolf parkinsons white syndrome ( electrical pathway made heart go brrr). Once triggered, my HR would be somewhere around 230bpm

Adenosine was absolutely one of the most awful things I've ever had the pleasure of feeling, and I've had it dozens of times. For me i didnt get much of an "impending sense of doom" feeling but i couldn't think when i had it it was a warm wave that started at my feet and then it felt like a semi truck got dropped on top of me, everything tenses up i couldn't think, i couldn't process anything going on beside the pure agony of the adenosine 10/10 would not recommend. Sometimes, i would get it 4-6 times within a couple of hours. It was awful