Feeling of a heartbeat in throat...what causes it?

I am a 39 year old male.  I am not overweight, but I have been having some chest pain under lower left rib, plus a feeling of like a heart beat in my throat.  A couple of years ago, I had some problems that led to my heart getting checked out, everything came back okay.  I watch what I eat, try to limit the fat and cholestrol.  My chol. level is fine, blood pressure runs normal to a little low 134/84 to 90/60.  What could be these heartbeat feelings??  I work during the day, and really don't want to take off time, if it is not serious.  I have read that it could be Pacs, Pvcs, or Afib.  How do you tell which one it is?  thanks

[CCF CARDIO MD - DLB]

It sounds like a heart rhythm/rate problem, such as PACs, PVCs, or afib. There is no way that you can reliably distinguish among these possibilities on your own. Therefore, a doctor's visit would be a good idea.

[earl]

I think Larry's question might be similar to mine.  I'm new to this forum, so I don't know much medical jargon.  I'm a 61 yr-old male with no personal or family history of heart trouble.  My cholesterol and BP historically are fine.  I'm overweight but otherwise in good health.  I've noticed recently (2+ weeks) that when I'm reclining and sometimes when standing or sitting, I can feel a strong pulse (but not an elevated rate) all over my upper torso (chest and neck), eyes, scalp and ears.  My normal waking resting heart rate is in the low to mid 60's, and although I haven't worn a monitor, I suspect it get down to the low 50's or below when asleep.  Several times recently I've awakened in the 4:00 to 6:00 a.m. time frame and noticed my heart rate is very strong and elevated (relative to normal).  This lasts about 10 - 15 beats, then slows down again.  I'm not sure if stirring around when I woke up causes it, or if the change in heart rate is what wakes me up.  I'm planning to take a cardiac stress test later this month preparatory to re-starting exercise to attack the weight situation.  EKGs over the past 20+ years have come back with the computer generated note, "Pronounced Sinus Bradychardia."  I've also had 4 - 5 stress tests over the past 20+ years with normal results.  From the mid 70's through the mid 80's I was distance running enthusiast and ran two marathons -- the docs said it was not unusual for distance runners to have sinus bradychardia, and I guess I still have it, but feeling the pulse and the sudden rapid heart rate in bed are new.