Atrial Fibrillation/Sick Sinus Syndrome/Exercise

[Sanson Corrasco]

I am a 60 year old male with a recent history of atrial fibrillation.  I have been symptom free except for shortness of breath.  I discovered it, using an exercise monitor which showed an elevated heart rate prior to exercise.  This caused me to seek an ECG and resulted in a diagnosis.

I am in sinus rhythm (100 mg flecainide 2X per day), but one of my doctors suspects sick sinus syndrome.  On rising bpm is ~50.  I have no dizziness or fainting spells.

I run 4-5 times per week, 1.5-3.0 miles.  My average bpm during my runs is 125-135.  Afterwards I get back in the 60-70 range and stay there the rest of the day except if seated for a long period.

My runs seem normal (if slow) except for the fact that during the first few steps, my bpm will jump to 150-155 bpm.  If I stop and take my pulse manually it will come in at ~90 bpm, but, having stopped to take my pulse, my monitor will show the same.  10 minutes or so into my run, my pulse will even out, 120-130, and stay there for the remainder of my run.  This high bpm at the beginning is more usual than not.

I wrote to the manufacturer of the exercise monitor to ask what was going on; they responded that the monitor registers erratic numbers in the presence of atrial fibrillation.  We knew that.

Can you suggest what is happening here?  Is the initial high bpm normal?  Is it a sign of afib?

[rhinoman]

I have been a runner for almost 40 years, though lately i have taken to biking to preserve the body.  I have been diagnosed with sick sinus syndrome, but have wondered if my condition was not induced by many years of competitive running. There are several things about my arrhthmia that make me wonder.  First, the bradycardia i have be diagnosed to have seems to me to be merely a consequence of physical conditioning.  in fact my resting heart rate at time of diagnosis was actually higher than
when i was younger, and since then has slowly crept up as i lose the level of conditioning i had.  secondly, my AR seems to be very position sensitive.  i almost always invoke it when i lie down at night for bed.  raising up slightly usually stops it, and after a while it seems to "adjust" to the new position and becomes less frequent.  my doctor believes i will eventually need a pacemaker, but he seems to be mostly concerned with the bradycardia.  i, on the other hand, am more uncomfortable with the tachycardia and potential for fibrillation.  

i was wondering if others had experienced any pain during exercise due to the arrhythmia.  the pain i have is transient, only a single beat long.  i have noticed that it is normally caused by an sino-atrially triggered pvc which occurs very soon after the previous beat.  this is usually followed by a longer delay before the following beat, which occurs at the expected time had no PVC occurred.  is suspect that what is happening is that blood continues to be "forced" into the ventricle during the pause, overstretching the heart muscle temporarily and causing the quick pain.

Regarding the initial rapid heart rate at onset of exercise, i suspect this is quite common if a proper warmup is not done.  i think it is merely a temporary overcompensation when level of activity is abruptly changed.  i have noticed it even in the morning (or especially in the middle of the night) when i get up from bed.  my heart will "race" for a few seconds and then settle back down.

i am curious about the heart ablation operation.  my doctor hasn't even suggested it to me, but my high school friend who is a doctor mentioned it immediately when i told him i had been diagnosed with sick sinus syndrome.

[pbanders]

I have to laugh, as the thing that seemed to get my problem to go away was to quit wearing my monitor for a few days! Too much attention to it was driving me nuts.

[pbanders]

I'm 46, I had my ascending aorta replaced with a graft in February, I've had SVT since I was 15. I am very fit and raced bicycles for a long time. I'm on 50 mg of Lopressor daily. I just had a 5-week episode with irregular HR (PAC's, PVC's, etc.) where my monitor (Polar) would not lock on to a reading at all. I wore a Holter and my cardio said "don't worry about it". I kept riding, as the irregular HR didn't seem to significantly affect my performance. The episode finally resolved itself last week, probably because I rode 150 miles over very difficult terrain during the week, and I'm back to normal HR readings on my monitor again. I'm also pretty sure that I'm fitter than I was before I had surgery, too.

I've just resolved to myself not to get too worried when I have PAC's and other irregularities, as long as I'm not experiencing any pain or distress. They seem to resolve themselves over time, which can be as long as weeks or months.

[runnertom]

I would not get overly anxious over what you see on the pulse monitor. I use one often, particularly when riding a bike and find odd readings to be rather common. Most recently when riding in Colorado where the air is quite dry, I was getting very alarming high readings in the first five or ten minutes of a ride. I eventually determined these to be due to poor contact with my skin before perspiration provided a better contact. I even wetted the belt prior to putting it on.
   I find the meter's response to arrythmia difficult to interpret. In general, PVCs cause it to "stick" on a pulse reading and refuse to update, presumably because the interval between pulses is too variable to assign a rate. I don't think it sees PACs at all. I would guess that it might give erratic results during atrial fib due to the variability of the ventricular rate at that time.
   It would be interesting to watch an EKG while wearing the monitor during exercise to confirm my theories, but I have not had the chance. In my case, I think wearing it results in more anxiety than its worth. I have taken it off my handlebars where its visible all the time and put it on my arm where I have to make an effort to look at it. I enjoy my rides a lot more.

[dquenzer]

I am a runner as well.  I had AFIB, but had an ablation, and now have none.  AFIB due to a runner's heart.  Runners are more susceptible to AFIB because according to my EP at Mayo they tend to stretch the pulmonary veins which is where much of AFIB comes from.

This isn't about that, but about your bpm.

I'm also a high school track coach, and one of the things I constantly harp on my kids to do is to warm up properly before they race.  They need to get the body ready to run.  They think they'll get tired out, but just the opposite occurs.

It could be you are starting out too fast, and not warming up properly.  Here's my suggestion.  Before you start to run, walk fast for at least 5 minutes, then run for a minute and walk fast a minute a few times, to just get a bit of sweat up or at least "wake up" your body. Then after you have done that start to run. This is especially true if you are a morning runner like myself.  I have found that when running in the morning you need to warm up more to get the body ready to run.

Hope that helps.  I hope I'm still running at 60.

[Clenn Camp]

I had bradycardia and sick sinus syndrone prior to implantation of a twin-lead pacemaker back in 1992.  What you describe is not sick sinus syndrone.

Glenn

[CCF-M.D.-MJM]

Hi Sanson,

Congrats on a great exercise regiment.

It is possible that initial surge in your heart right is just your heart "warming up" to the workout.  A holter monitor will provide an actually EKG strip and will help answer the question.

This doesn't look like sick sinus syndrome to me.  It sounds like you have an appropriate heart rate response to exercise.  It is in the 50-60's at rest, increases to 120-130's with exercise and returns to normal with rest.  I think a holter monitor will straighten out the question what the rhythm is the first few minutes of your run.

Good luck and keep up the running.