Tachycardia while running?

[Tiago_Fzz]

Hi all, have you found the causes of your SVT sarahmg and helzbelz1984? 
I'm 36 year's old and I used to run a lot, but on the last two years I stopped running that offten, so in was decided to start to be the "running machine" and started training on November 2017, everything was going fine until my first SVT while running on 25 March 2018, I was about to cross the 10k when suddenly I felt something on my chest, lack of strength and air, some pain, I couldn't bread no more, I felt like I was going to collapse right there... when I looked to my Garmin I was with 185bpm while stopped, and I remembered that I had checked a few seconds before while going down the street and i had 145bpm, I started to panic thinking I was going to have a stroke out there alone without anyone to assist me... after a few minutes my HR dropped to 145bpm ( this tooked 7min between 145 to 185 and back to 145...)  it was a very scary experience... I did some exams, stress test, 24h holter, echocardiogram, ECG (bradycardia), and they all checked normal, but I this week I started running again, I went for a 10k run 2 days ago, everything checked ok, while this morning I was running while my wife was ridding her bike, I had done like just 3k when suddenly there was the hit on the chest, the lack of air, and some dizziness, but mutch more weaker than the previous experience... this time I was with my wife who helped me to calm down, because if you get scare can be worst my HR went from 130 to 185 stayed there for 30 seconds and it went down again. After this I rested for 10min and went back on foot to the car, 3k more... 
My wife says it can be a panic attack, due to stress, but I was feeling great, and I think, shouldn't it happen when I'm not running? 
I still don't know what it was, but I know what I felt and it wasn't panic (I had panic attacks 7 year's ago and I know how do they feel)
Does anyone know anything about this? 
What can trigger this while running?

(Sorry for my English