Coming over from the Crohn's board

Hello everyone :)

I usually post on the Crohn's board (because I have Crohn's disease), but lately I've been experiencing a lot of Cardiovascular problems. During any given day, my heart rate is usually between 110-170bpm, it's even gone as high as 200 on some occasions. My blood pressure is pretty stable, but can get wacky, such as being 97/79 or 90/70, especially when I stand. When I'm standing, it's the worst. My heart rate just doesn't seem to go back to normal after I stand. It either stays high, or goes higher and stays that way. I experienced a "silent heart attack" January of this year due to hypovolemia from dehydration and was in the ICU and all that fun stuff. After that, my heart hasn't been the same. I have an appointment with a cardiologist on the 10th of September, but I want some idea of what this might be. Any thoughts would be appreciated.