Hi I am a 37yearold woman, I have been officialy been diagnosed with an enlarged heart, very high blood pressure, and an irregular heart beat, where it beats so fast I have to have shots at times to slow it down, I have two 2 leaky heart valves, and arteriolschlerosis. and one of my EKG s has showed thatmy heart is not functioning as it should be period and I am developing a blockagein one of the arteries that leads to my heart. Lastly I have a heard time catching my breathe during any activities, and I get dizzy whenever I do any activities. My question is; when is a increased heart and pulse rate dangerous? I ask this because just to night my heart started beating like this. thump, thump,thump,thump,thump, (pause) thump, thump, imagine this pattern going really fast repeatedly to the point it scared me and I could feel it and hear it, and when I checked my pulse, it was; thump, thump,thump,thump,thump, (pause) and thump, thump,thump,thump,thump, (pause) and it continued.