I have tachycardia (fast heart rate). My resting pulse is very rarely under 100 bpm. Had this problem for several years. About 4 years ago I had some tests done like a heart ultra sound and also wore a monitor for 24 hours to track it. Saw a cardiologist. No one could explain why it was fast. Good news was it was always a regular heart beat. When I've seen other doctors for other things over the years I have gotten comments about it. It bothers me quite a bit actually. I get exhausted so easily.

I'm taking an amphetamine for my ADD and thought maybe that was causing this. I talked to my pdoc about it and we did an experiment for a few days where I went without my medication (was terribly grumpy). No change in my heart rate. That would have been too easy I suppose.