I have a pacemaker implanted and I know I am in constant Afib. I recently had my pacemaker checked at the arrythmia center and was told I am in constant Afib. Tonight sitting at my computer, my heart started to race and pound for approximately 60 seconds. It felt as if my heart was going to jump out of my chest. Has anyone had a similar experience and what did you do? My 1st pacemaker was implanted in Sept. 2000 and my 2nd was implanted in January 2008.