I had one last year M. I was really apprehensive about having someone speed my heart rate up with a medicine, but it wasn't bad at all. I had to lie still, on my left side...they put the med in and slowly sped my heart rate to I think it was 136 beats a minute. A doc was in the room doing the reading once the desired rate was met...then they started slowing the rate down...only took a few minutes total. Just felt kinda weird lying still and my heart beating like I'd ran a couple miles.