running - pacemaker upper limit and vtach

Had my pacemaker put in for bradycardia/sic sinus syndrome earlier this year. I run a lot, so was eager to get back to it as soon as possible. On follow-up visits, they noted that my pulse had gone above 200 on a few occasions. 

Comparing to my Garmin tracking, it looks like when I run my HR quickly gets up to 140, which is the upper pacing limit for the Pacemaker. Then, it is pegged at 140 for most of my run. BUT, sometimes towards the end of the run my heartrate suddenly climbs out and shoots up towards 200, and then takes a while to come back down.

My legs also often feel tired as I am running. One thing that occurred to me is that perhaps because my upper chamber doesn't fire without the pacemaker most of the time, when the pacemaker topped out at 140, but I was exerting effort that might have had my HR normally go higher. Since my heart isn't going to go higher, it stays at 140 -- but that isn't high enough to pump enough blood. And then, perhaps if I keep overdoing it at that rate, that causes the rapid spike to 200?

Anyone else have similar experiences? I know a rep from Medtronix who said that it might make sense to raise the upper limit higher if I am going to be running at this level (and I have a race this weekend). Still waiting for the cardiologist to get back to me, but curious what experiences others have had in how to request adjusting of the pacemaker. I get flutterings in my chest, or very tired legs when running or doing squats, and wondering whether these are things that require more tweaking.







by doublehorn48 - 2021-08-23 18:13:39

My upper limit has always been 160 and my lower one at 60.  I don't think a Garmin watch is a  very accurate measure of a person's heart rate.  I know it certainly gets mine wrong.  My Garmin is great for measuring distance and pace.  

garmin chest strap

by justjoe - 2021-08-23 18:19:49

I got a chest strap to be more accurate, and it was a little more consistent but surprisingly close to the watch. I originally assumed some of the readings were mistakes by the Garmin -- it was only after I compared notes when they were reading the actual data from the pacemaker that I realized that Garmin was pretty accurate, or at least was in the range. Every time they told me they saw something strange on my pacemaker, it synced with Garmin activity and HR. But I think increasing the upper to 160 like yours may be the answer. 

Running - Pacemaker/AFIB

by abbelbruno - 2021-08-23 18:24:23

Hi Joe - 

I'm a runner too and have had weird HR readings since receiving my pacemaker for SSS. Mine is set at 60 and also tops at 140 but mine is only to control my HR not going to low. The thing is I also have AFIB which I think your headline says you have but didn't see you write it in the body of your post (sorry if I missed it). I know the Garmin won't catch it if while we're exercising if our heart is trying to go into AFIB or is is in AFIB therefore you'll get random and sometimes elevated Heart Rates. The only reason I know my heart tries to go into AFIB sometimes while running is it was caught during a treadmill stress test. Have you done that yet? Might be something to consider. Good luck! 


by justjoe - 2021-08-23 18:31:14


Sorry, meant vtach. So it seems my heart rate either pegs at 140, or if it goes higher may be vtach. 

They wouldn't do the treadmill stress test for some reason with pacemaker -- they simply raise my HR through the pacemaker. But I may ask if they can do that, since I'd like to more closely know what happens when I run. 

Sounds like exercise-induced atrial tachyarrhythmia

by crustyg - 2021-08-24 04:32:06

I have this, but not as much as a I used to.  When the arrhythmia hits, cardiac output drops as you lose the A=>V sync, so each heartbeat from the LV pushes less blood out into the aorta, and the working muscles quickly go into anaerobic work, and you feel tired/terrible/sick/jelly legs.

My EP doc and I discussed this and I used it to get my PM's upper limit raised to something sensible for my heart fitness+age (much higher than 140BPM).  There is *some* evidence that allowing a PM to drive the atria faster actually reduces the risk of an atrial tachyarrhythmia from becoming AFib (for SSS patients).

I still get the occasional problem when cycling up mountains, seems to be related to getting too dehydrated and still pushing hard.

I'm a keen runner and cyclist

by quikjraw - 2021-08-24 05:19:33

Before my pacemaker was fitted I would often get upto 180bpm on a run according to the chest strap on my garmin having used it for many years and looked at nearly every graph I would suggest was a real set of data. These were not blips though you could see on the graphs that my heart rate steadily creeped up to 180ish and stayed there if I kept the intensity.

I had a pacemaker fitted for heart block, I do not have sick sinus syndrome though.

My pacemaker was set with an upper tracking rate of 150bpm. So when I did the treadmill stress test at the hospital they disovered that although my atria were firing at around 170 to 180 during the higher intensities of the test my ventricles were "maxxed out" at 150bpm. I could see it clearly on the screen a constant 150bpm through the ECG leads.

They then changed my upper tracking rate to 180 and i instantly saw my heart rate jump from 150 to above 170. It felt noticeably easier.

This sounds like you need something similar sorting using a treadmill stress test. The downsides for me are that to enable tracking of my higher heart rates the pacemaker can not wait as long as it previously did for my own ventricles to fire so I am now paced 100% of the time according to my latest download.

ventricles were "maxxed out" at 150bpm

by AgentX86 - 2021-08-24 14:28:15

This is a correlary to what Crusty was talking about.  If you sinus node pushes your heart rate above the max tracking rate, well, the ventricles will stop tracking the atria and you lose A/V synchrony.  Not only do the ventricles not pump faster, they pump less with each contraction because they no longer have the help of the atria filling them (that[s what the atria are for).  In fact, it's worse than that because, at times, the atria will be opposing the ventricles. 

As Crusty hinted, as long as the tracking rate is set too low, you're going to have this problem.  Your EP, for any number of reasons, may not want to increase this and you're stuck.  A/V dyssynchrony isn't great for the heart either, though.

update -- will be adjusting upper limit

by justjoe - 2021-08-24 16:00:10

Talked with my practitioner, who agreed we need to raise the upper limit. Unfortunately they can't do until Monday, so won't help my performance in the 10k on Sunday, but sounds like they are in agreement that it needs to be higher and looking forward to seeing what an increased upper limit does to my performance. 


Great news and for the data geek in me...

by quikjraw - 2021-08-25 08:31:25

Great news  justjoe and good luck on Sunday.

You have an absolutely unique situation to monitor the real performance effects of this new upper limit.

You will have your time on Sunday and you could see in a couple of weeks how your time looks when you do another 10k of similar terrain.

I'd be really interested in seeing how those times differ if you feel up to doing that and posting?

AgentX post shows that there was more to not matching A/V activation than purely just heart rate. So I suspect that your next 10k will almost certainly be faster  all other things (like your recovery, legs etc. )being equal.

All the best quikjraw

PS garmin chest strap and optical

by quikjraw - 2021-08-25 08:40:29

I know others will wade in on this topic but this is my opinion and experience.

I too am a keen runner, before implant last year I was getting close to running a mile in 5 minutes so I know a bit about my own heart rate and pace.

I have used a garmin chest strap for biking and running for about 5 years. They are very good no doubt about it. I have looked at lots of the graphs and see very few strange looking readings.

After my pacemaker was fitted neither of my two chest straps worked any more. I thought it was battery but I changed them both but they still did not work.

I've read others have the same issue.

I took the plunge and bought a garmin optical hr watch (fenix 6 pro it was on offer :)). It has been very reliable but if you do get one here are my tips.

1)It needs to be tight when exercising.

2) I have hairy wrists so a shaved a tiny spot to make my vein more visble for pulse oximetry sensor. To be clear it worked well for heart rate without me shaving the wrist.

On seperate point my watch will alert me if my heart rate goes above a set limit (which I can set) when exercising or below a set limit when exercising. It would only drop to a low limit if my pacemaker stopped working but for the higher limit it could be useful to know this was happening once you gain more confidence in its use.

post adjusment 10k run--all good!

by justjoe - 2021-08-30 09:41:27

quikjraw asked if I would post the results after having the pacemaker adjusted.

Friday had the pacemaker upper range set to 160, up from 140. I did a test run of a mile that night -- I started at a pace just under 10 minute, but ended at 7 minute pace, and for the first time I felt good at the faster pace, which boosted my confidence. 

So the 10k -- ran it in under 9 minutes/mile. The best I ran since I had the pacemaker installed in April was 9:20, and at times I had struggled to run a 10  minute pace, and would get light headed and my legs would fee dead. I was still being somewhat cautious, but this gives me confidence I can start training harder, and continue to improve and start to run faster. 

Fantastic news

by quikjraw - 2021-08-31 09:08:34

Thanks for posting that Justjoe, it is fantastic news.

As you say yourself, take it easy but this does sound like a real help to you.

All the best


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I had a pacemaker when I was 11. I never once thought I wasn't a 'normal kid' nor was I ever treated differently because of it. I could do everything all my friends were doing; I just happened to have a battery attached to my heart to help it work.