I am a 41 year old white famale, 5'6, 240 pounds, moderately active.  I first noticed heart palpitations at age 19.  I wore a Holter monitor and they found sinus Tac and sinus bradycardia.  ( forgive my spelling )  I was told to avoid stress and caffeine.  Most of my life I have been caffeine free.  I also limit sugar.  In the past 5 years I've had more frequent palpitations.  I have had episodes of rapid and irregular heartbeat that scared me but they have been called "anxiety attacks."   3 months ago I had a very different and more intense "anxiety attack" that lasted 2 weeks and included clamminess, sleeplessness, and rushes of adrenalin that lasted days at a time.  This passed after a while but since the episode my heart will skip and then thump hard ANYTIME I exert myself more than day to day activity.  EKG is normal.  Echo report says ( and I'm trying to read the handwriting... )  "Normal ejection fraction with mild mitral and tricusped regurgitation.  O.K."  For the past 2 months I have been taking .50 mg Toprol.  I had been given Zoloft and then changed to Lexapro after the "anxiety" episode early June.  I stopped taking the Lexapro and the palpitations became less frequent BUT anytime I exert myself ( example going to the top row of a movie theater, or trying to use the eliptical at the health club ) my heart will skip and thump so that I have to stop.  Being overweight and having heart issues it's very important to me that I can exercise!  This is very frustrating.  Any ideas?  I suspect I am having some perimenopausal issues.  Certainly life is stressful but I have friends and family and my christian faith that give me much comfort and support in my life.  Thanks for reading my question and I look forward to your reply.  -C-