I still get the feeling of my heart beating fast. Sometimes it's not, but it feels like my HR and breathing don't match up. When I ride my mountain bike my HR easily goes up to 170-180s which isn't right. I remember last year before I got the Mirena out I would ride my bike and my HR would go over 200. That is definitely not right. I'm pretty sure the Mirena did something to my vasculature. I put off going to a cardiologist because over the past year things seemed to be getting better (my heart palps pretty much went away). Now sometimes I feel like I forget to breathe. Anyway, I can't ignore these symptoms anymore and I have an appt. on Friday.