I'm 21 and last night I ended up in a&e, I could feel my heart pounding through my cHest but I was sitting down not doing anything to make my heart gear up. After around 2 hours it became worse I started sweating i was struggling for breath even long inhales Didn't feel like air. Just as I got to a&e I nearly fainted and had pins and needles in my hands. It was so scary in total it lasted around 3 hours I have experienced a fast heart beat for no reason before but never to the point that it's bothered me. Anyway my blood pressure dropped whilst I was there and the doctor seems to think I have SVT but the ecg wouldn't pick anything up as I'd left it so long by the time I got to the hospital it had returned to normal leaving me quite drained. I have to have an ecg when it happens and i have to ring 999 immediately. Does this sound like SVT? I'm terrified it's going to come back it was so scary! I have a history of heart problems so I'm nervous.