About a year ago I experienced what they told me was an episode of SVT. I had been walking on a treadmill with an incline and noticed my heart rate rise very quickly. I look fit, but i'm not. My heart rate always takes a while to come down as well. It was approx 10-15 after leaving the gym that I got dizzy and my heart rate shot up. I didn't know what was happening to I called 911. By the time they got to me, my heart rate was back down to around 84. They hooked me up in the ambulance and fortunately it happened again. They were able to catch this fast rhythm on their machine and I was later diagnosed with SVT in emerge. My heart rate only went up to 140, which some say isn't SVT. I had an echo, a stress test, and 2 holder monitors-all normal, other than PVCs and PACS, which I had been told years prior I had. What I have been having for the past 6 months feel worse than the original (happens randomly, with no trigger) "SVT." I can almost feel it coming on, as I get this weird dizzy sensation followed by a rapid heartbeat. It lasts anywhere from 10 to 30 seconds. I do check my pulse but I can't tell whether its regular or irregular. The dizzy feeling almost feels like i'm floating or my head is going to explore, it's hard to explain. I'm really worried this is more than just SVT and that is something like Vtach. Any information would be greatly appreciated. I am afraid to do anything that gets my heart rate up. I gave up caffeine about 4 months ago, I rarely drink now because of this, and I've never smoked. I am a 26 year old female around 128 pounds.