For some time now I have been experiencing heart palipations then almost 2 years ago it got more serious. I went into tachycardia for a good 5 minutes with heart rate over 300 bpm. Have been to tons of cardiologist. One finally put me on atenolol 25 mg said it would help. BUT I have been on this pill over a month and I keep a heart diary. I have recorded for the last 6 plus months that I have palipations everyday and they stop me in my tracks, I am usually exhausted no matter how much rest I get and I am quite moody, oh and I get short of breath as these palipations are lots of them at once. Anyway I have noticed that I have about 5 days every month that I dont have even one misbeat, I feel great and energic. Then all the sudden they start back up and I am back to the sick me. I think it is hormonal and I cant get a dr. to help me. Does anyone know anything about this. I need a real Doctor to help me one who want to find the cause. I have clues it is not true tachycardia but hormonal.