Heart Palpitations

I have recently been noticing that after intense excercise (over 90% of max. HR) I have a pounding heart rate and feel a little short of breath.  This happens 1-2 hours after the exercise.  I exercise often (6 days/week) and am an avid cyclist.  I rode yesterday for 5 hours, including an hour long climb at a HR of 170BPM.  2 hours after I had completed my ride I noticed an uncomfortable pounding heart beat (it didn't seem overly fast) and a little short of breath.  It lasted about an hour. I think I was well hydrated and used electrolyte sports drink (Gatorade) and water during the ride.

History:  Am 43 years old, in good physical condition.  Was treated for SVT (brought on only with intense exercise) with an ablation in January 2006. I take thyroid meds (Levoxyl 125mcg.) and levels have been recently tested.  I also take Nasacort, Clarinex, Nexium.  

Could there be a chemical or electrolyte inbalance causing these symptoms?  I also have a lot of stomach discomfort (due to reflux) during long rides.  Could this cause these heart symptoms?

[Michael J. McWilliams, M.D.]

Hello,
If the palpitations are similar to what you had prior to your last ablation, then it may be a recurrence or might be a completely different arrhythmia.  Electrolyte imbalances cause arrhythmias, but they are usually significant imbalances and very rare.  You need to talk to your doctor and arrange for either an event monitor or home telemetry.  The only way to know what it is is to see it.  I would prefer this rather than just bring you to the lab and doing an EP study -- it is much easier to know what you are going after so your doctor will know how to fix it if it is an arrhythmia.  Reflux is a very unlikely cause for a racing heart.

I hope this helps.   Let us know what it is when your you and your doctor figure it out.
Thanks for posting.

[kitcurious]

Your post is interesting.  I also cycle, but only 3 to 4 times a week. I rode for only two hours this morning and got my typical result upon returning home . My  heart rate remained in the 130s for a good hour afterwards. I also drink sports drinks to remain hydrated and don't undertand the prolonged recovery time for the rate.
Coincidentally, I am also taking Levxoyl (75mcg). I have MVP but that isn't it I'm sure, that doesn't do anything.
My average BP measurement has dropped 20 points lately as well. It's now in the 100s over 60s
Oh well. I hope you get to the bottom of the situation.