What will cause the heart to pound and beat very fast?

[Platypus0]

I am 19 F.
My heart was suddenly pounding and beating very fast. I felt hot/warm and my face became reddish.

I don't know what triggered it, but it's possibly either because I ate too much or I altered my breathing pattern.

This pounding continued for two days. I thought it would stop as soon as I went back to my normal breathing pattern.

From the third day until today (two months after that incident), I experienced symptoms like:
Lightheadedness, Giddiness, numbness, chills, fatigue, muscle twitches.

The doctor ordered various tests (bloodwork, thyroid, ecg, echo, chest xray) which were all fine. He says I'm fine.

Should I worry about anything (eg pulmonary hypertension)?

[tom_h]

SVT starts up and stops on a dime; within one beat.  It's the oddest feeling.  When it halts, there's a sudden stillness, a quietness within your chest.  A 30 day monitor might catch what you're feeling.  Easy to wear...

[tom_h]

13p to 140 is not particumarly fast for SVT.  Uit the sudden onset as you described is a sign of it.  It also ends as suddenly as it begins.  It seems almost instinctive to either cough of breathe in deeply when the rapid pulse begins.  A medical exam when this is not occurring usually reveals a perfectly normal heart.  If this happens again, you should measure your pulse rate, note how it begins, and how it ends. Does it slowly ramp up and ramp down, or does it start and end seemingly in one beat?  These are important clued that can aid the physician make an accurate diagnosis.

[Platypus0]

actually, my heart rate became pretty fast all the time from that point onwards. I think it slowly ramped up. But thanks for your advice :)

[tom_h]

During this episode, did you measure your pulse?  If so  how fast was it?

[Platypus0]

Thank you for your response :) Unfortunately I was unable to measure my pulse rate during that one episode. I am guessing it should be around 130-140 but I can't remember (the feeling is similar to when I drank lots of caffeine once)

What could have happened during this episode? Thank you.

[Platypus0]

Additional info: when I mentioned strange breathing pattern, I don't exactly know what it is. I think I was doing something similar to a Valsava manuever to push out/inflate my abdomen with air.

[achillea]

Why were you trying to alter your breathing pattern?

[Platypus0]

I wanted to see how far my abdomen would enlarge, so I did a breathing pattern to kind of pump air into it. (maybe it's a fetish)

[achillea]

It certainly is weird.  Frankly, I'd skip that, if I were you.

[Platypus0]

Yes thank you. I learned exactly that from this episode. Of course, I'll never do it again. But more importantly, did something happen to me?