Heart Rate DROPS Suddenly during Exercise.

[Toecutter666]

Hello everyone,

I’m writing on behalf of my wife Judy who has, it would seem, some very unusual things going on with her heart rate during exercise.. I have googled my head off over this, and cannot find discussions relating to this type of occurrence.

About two out of three time she goes running, always with her Garmin watch and HR strap, she will experience rapidly climbing HR to a level quite above her MAXHR, and then typically after about 6-8 minutes of jogging/running, her HR will drop quite sharply.  She always continues to run from this point, and after the sudden rise and drop of her HR, the HR graph looks completely normal in that her HR will slowly rise over the duration of the exercise.

The prevalence of this was lesser until about 18 months ago, when it became far more common.

She experiences no dizziness or reduction in performance, any only really knows about it when she gets home and we look and see “that thing” again in Garmin Connect…

Here is a link to Garmin Connect for one such instance: https://connect.garmin.com/activity/658118669
NOTE: She stopped running after 33 minutes due to injury.

This one is odd, we cannot explain it: https://connect.garmin.com/activity/680844946
NOTE: HR Climbed dramatically given she *walked* to warm up (see cadence/pace).  After 15 minute mark, HR behaviour was “normal”.

We have tested various straps and monitoring systems, contact gels, fresh batteries etc, and given this has been happening for so long now (three years to varying degrees), we’re certain it is not a technology issue with the strap or watch.  We have successfully duplicated her problem with my strap and watch (and I have never had a poor reading when I have personally been using my gear).  The heart specialist agrees this is not a monitoring error.  It is just far too common and consistent in behaviour.

It is far more prevalent with running, as distinct from cycling or walking, hiking etc..  During these other exercises, her watch and HR sensor work perfectly.

Temperature or time of day do not seem factors.

She is 41, and very fit.  About a year ago, after experiencing a period of frequent palpitation episodes, she was diagnosed with a minor Prolapsed Mitral Valve which did not raise any great concern at the heart clinic.  The palpitations have not settled in any way, but we are now less concerned about them.

Because of our concerns over the sudden HR rise/drop issue, she is now seeing a Heart Specialist.  She has had an Exercise Stress Test which did not duplicate the issue (mainly as the load was gradually increased, it perhaps did not replicate the *sudden* onset of exercise).  She has also spent some time with a portable Loop Monitor that, due to phone line transmission problems, and poor administration at the hospital, yielded virtually useless results.

Her specialist is somewhat at a loss, and while he concedes there *might* be a problem, is now suggesting she has an Insertable Cardiac Monitor for TWO YEARS.

I apologise for the lengthy post, but I wanted to give all relevant information.  Our question is, should we be concerned?  Has anyone else experienced this, or even heard of it?

As you can see from the link to her Garmin Connect session, her HR can get above 250bpm very early in a run, then settle to 150pbm after 6-8 minutes, which is where her HR should have been with 6-8 minutes running performed.  The drop down is very sudden – probably over about 2-3 minutes.  This is probably the most extreme example I could find, but it shows the nature of the events.

Any concerns?

Cheers, Matt.

[hefner33]

Hey

Sorry. R-R is this spikes in your heart beat. If you've ever seen a picture of your heart beat, the R point is that peak of the triangle. http://www.learntheheart.com/ecg-review/ecg-interpretation-tutorial/qrs-complex/

PACS (premature atrial contractions)= Are a quick extra heart beat that is fired off earlier than your normal rhythym that originates from the top part of your heart. http://www.cardiachealth.org/premature-atrial-contractions-pacs

As I can't say exactly what yours is showing, yes a HRM will pick up what its things are normal beats. So think of it this way. When you have a very fast heart rate, the beats are close together, and your HRM measures that R peak(shown earlier) on the heart beat. The closer they are the higher it shows on your device your heart beat. Well what happens with me, not saying you, is that I throw alot of PACS at the beginning of exercises from adrenaline. I have shown this on stress test in the past. As the adrenaline wears down, they stop so my heart rate would go back down a little because the R-R's are being measured at a further distance from each other than when throwing the PACS.

I am just able to pick these up using that HRV (heart rate variability) app with my hrm because it plots the R-R intervals on a graph. Heres a screenshot I took a while back showing this https://goo.gl/6e1b9c

[VCJohnson]

Your wife, Judy's, experience sounds similar to mine.  I experienced approximate 50% HR drops suddenly during intense running and cycling.  Also, I had prolonged high heart rates, up to about 150, following exercise, for up to 4 hours, as displayed on my Garmin monitor and simultaneously confirmed using a blood pressure cuff.  I went to the ER during once such prolonged high HR event, 2.5 years ago.  The EP/Cardiologist there diagnosed 2nd degree Mobitz 2 heart block and recommended a pacemaker and implanted one a few weeks later.  He didn't diagnose SVT.  It was one year later that another EP finally diagnosed SVT/AVNRT.  I had an ablation for a slow electrical pathway very near/in the A/V node.  Doing very well now during running and cycling with only a few, seldom ecotopic beats felt.

Good luck to Judy and you.  From my experience, if you're not 100% confident in your Cardiologist/EP, don't hesitate to get a 2nd opinion from another one.  If I hadn't gone to another EP, I'd probably still have SVT.

[Toecutter666]

Thanks hefner33,

Please excuse my ignorance, but could you briefly explain what PACS, R-R Intervals and QRS are?

I *think* you are suggesting that the Garmin HR Monitor is picking up signals that are not necessarily the biological (real) pulse, but rather some type of signal that is being confused for pulse rate.

Cheers, Matt.

[hefner33]

One siggestion I might throw out there cause this happens to me is she has adrenaline induced pacs at the beginning of exercise. The hrms measure hr but counting the distance between the r-r intervals (of the qrs complex). When you throw alot of pacs at the beginning of exercise it will count very short r-r intervals, which in turn shows a high heart rate. When the adrenaline begins to wear off and you go back into a more normal sinus rhythym, your hr ahows more to your norm..

You can actually see this happening with a HRV (heart rate variability) app on your phone that I use. Its card HRV expert by cardio mood. It will graph each r-r interval on a line graph. Pretty neat stuff

[Toecutter666]

Thanks itdood,

Unfortunately, the CardioNet Monitor is unavailable to us here in Australia.  However, as you and Michelle have made clear, proper testing to capture these events is our primary focus right now.

Incidentally, my wife has been moved to another cardiologist (not at our request..), which at least opens up the possibility that the next guy has better ideas how to approach and diagnose this.

Thanks all for your input.

[itdood]

Michelle has great advise.

When I was having issues I used a CardioNet monitor which I wore for 14 days.    I liked this one the best.  It wasn't one of these crappy cardiologists' office monitors.  those things are crap and the technicians never have them setup right.  Sorry to the good techs out there, the ones I've dealt with were miserable and incompetent.  If it weren't for the amazing ability of a heart to keep beating at all costs these folks would kill more people.  Anywho, as you can tell I, like most people, had bad experience with those holters.  lol

CardioNet doesn't provide them through the cardiologist's office.  Your doc orders it and CardioNet ships it to your house.  CardioNet specializes in this so the monitors, in my experience, are setup correctly, the internal clocks are set correctly, and whenever I pressed the button for an event it matched the strip.

Mine had data built right into it, and it connected via mobile service.  

When I was done, packed it back in the box and shipped it back.  Then I met with the doc for the report.

[Toecutter666]

Thanks Michelle - good advice and information.  :)

[MichelleP_3811]

yes, I would definitely do that to see what is going on though I find it highly interesting that she doesn't sense a thing.  when my heart was beating at 230 it felt very manic and was super difficult to breath.  I had to sit down and felt as if I would pass out.  Exerting myself to walk or even talk took all my breath away so it is interesting that she doesn't have any symptoms with it but the rate seems pretty high so it is worth getting evaluated.  

As for the loop recorder it is actually a super useful tool for catching my type of svt which was very random and did not happen every day.  I could not replicate it like your wife can fairly consistently when she exercises.  For me I would get it randomly but at least once a month so the loop monitor was good to catch it and all the doctor really needed to see was the start of the arrhythmia to have a pretty clear indication that I had an svt that was correctable.  The biggest issue though is that those types of recorders need an analog phone to send in the results and people don't necessarily have one of those.  I had one when I had the monitor but we have since gotten rid of it.  I hope they update the technology to accommodate that but in general holters are good for daily symptoms while loops are good for transient symptoms that are harder to catch.  In generally the doctor really only need see a few seconds of any arrhythmia to know what is going on but for svt it is best to catch the start.  Anyways, I would push for the holter first and have her do her normal run both days if possible to get a 48 hour one and then resort to the implanted one if you are unable to catch it.  Best of luck.

[Toecutter666]

Thank you Michelle.  

I would have thought a Holter Monitor would have been used for diagnosis, but the doctors gave Judy a loop monitor that seemed like 1970's technology in that she could record no more than a few minutes of data before she had to use modem-like data transfer over the phone line to "empty" the device for further use etc..

I suppose our concern is that when she starts to exercise, her HR will rise to extreme levels and stay there for several minutes, then drop back to much lower levels.  Intuitively, this just doesn't seem "right".

We will press for further testing that can capture the phenomena better.

[MichelleP_3811]

There aren't many doctors who come by this forum so not sure the level of advice you can get from this site.  From my experience a 3 minute change in rate isn't considered sudden.  Sudden is within a beat or two.  I had an svt where my heart would beat at 230bpm for no reason at all but it started and stopped in what felt like one beat.  Her rate changes over a minute or more which is typical for how a heart responds when one is starting or stopping an exercise routine.  I really don't have any other knowledge to give on the subject except to say I would first try a holter, maybe a 48 hour one before going through the trauma of inserting a monitor inside myself.  If this is a pretty typical result she could have 2 days of trying to replicate it for the doctor to see if the heart beat is normal but fast or if it is actually beating in an irregular way.  Considering she doesn't have any outwardly concerning symptoms like severe shortness of breath, chest pain, dizziness or passing out from what is happening it may just be the way her body responds to physical exertion but I do think it important to rule out any arrhythmia which could be dangerous.  But in the absence of symptoms that prompt her to stop exercising it could be something normal for her.  Well best of luck getting to the bottom of this.  Please do keep us posted.