Doctor, I have irrgular heartbeat attack twice two years ago and since then have been feeling a sudden twist or flip of heart for even less then a micro second but get normal after this. With this I feel my head circling and afterwards feel drained for some time. Since last one month I am facing another problem which started suddenly that sometimes while sleeping or trying to sleep I feel that my heart had started sinking and when I feel my pulse that time it is double beating at that time. I wake up and cough and drink water and then its OK for that time. But it is fistubing me a lot. Can u explain what is all this. I have done ETT with Bruce protocol and it was negative. Echo is normal. Holter test twice for 24 hours. Nothing during that time. I am very worried. Please answer me. I am taking loprin 75 mg and tenormin 25 mg since last two years.