Attending to breathing gives me a pounding heart.

[FeeHutch]

I remember becoming very aware of both my breathing and my heart beat when I first started mindfulness and I found it off putting and sometimes the sensation strangely made me feel sick!

It mostly settled as I got used to it thankfully so no advice to add just a bit of empathy

[Mudlotus]

I remember becoming very aware of both my breathing and my heart beat when I first started mindfulness and I found it off putting and sometimes the sensation strangely made me feel sick!

It mostly settled as I got used to it thankfully so no advice to add just a bit of empathy

Me too: I always feel the heart and blood to be a bit 'icky'. Today I noticed a heavy pumping of my elevated heartbeat during a bodyscan. But I decided to allow it and befriend it. It's a working heart; a blessing. Somehow it's agitated, so that's there and probably the best option of the moment, including the feeling of nausea. I thought: "I accept!"
The heavy thumping didn't stop from this, but the nausea did.
Remember that 'the way you are feeling right now is the way you are feeling right now'. I've been noticing how it can actually be a beautiful feeling to be able to accept that.

[RMJS]

The same thing happens to me. Regarding the replies, telling somebody that their problem is “psychosomatic“ does not help them fix the problem. I understand some of the people who have replied are trying to be helpful, but this is very unhelpful. I would be willing to listen to some people who have had the same experience. My heart rate becomes insanely irregular and I cannot tell you why. I wish I had a solution for you but I do not. For anyone else who has an actual actionable suggestion, that would be nice.