What is a dangerous heart rate - Elevated Heart Rate Most Likely Caused by Medical Condition

Is there a point, either after a certain period of time or at a certain heart rate, where one should stop and recognise that the heart is beating dangerously fast and needs to slow down? Sometimes as you stand for the first 15 to 20 seconds, your pulse may go up a little bit, but after a couple of minutes it should settle down.

I'm 16 years old and my heart rate feels different and I have acid reflux but sometimes I feel like someone's sitting on top of my chest and I'm gonna stop breathing then it freaks me out so I get these pains and my heart rate increases cause I'm scared and my parents think its just the acid reflux but it feels weirdly different to me.

A few hours later her heart simply stopped.