sudden heart rate drop while running

Hello, all. I got my Boston Scientific ACCOLADE MRI Pacemaker (dual chamber) on July 29, 2019. About three weeks ago I resumed running after getting cleared by my doctor. I'm rather deconditioned from not run for about 12 weeks. I have been going out every other day for very easy, 20-25 minute runs. My pace is very relaxed, about 13-minute miles, in which I have complete control of my breathing. I could easily carry on a conversation at this effort. My heart rate at this pace is usually between 130 and 145 BPM. 

On almost every run, I've had an episode which lasts for 30-60 seconds where my heart rate suddenly plummets from 130-145 BPM to about 80 BPM. Almost instantly, I lose my breath, my legs lose all their strength and I feel light-headed. Then, 30-60 seconds later, I feel fine. My heart rate goes right back up to nearly where it was, I catch my breath, and I can continue on. 

I reported this to my EP and they adjusted my device ceiling to 160 BPM. It had been set at 130 BPM.

However, on my last run after the adjustment, I had the same experience. Has anyone else experienced something like this while exercising?


Need more information about your settings and condition

by crustyg - 2019-09-20 19:06:08


I can think of some scenarios where this might happen (I *think*) but would need to know a little more information - pacing mode, and additional settings, and to know what, if anything, was in your Arrhythmia log at your last interrogation (when your max was raised to 160).  And possibly some information about the underlying heart issue that lead to you being paced.

There's at least one feature of your PM that might do this.

What did your EP doc/tech say as explanation when you reported this?  Do you have a copy of your full interrogation report?  They can give you a copy of *everything* on a USB stick (thumb-drive) for you to take away and study at your leisure.


by Tracey_E - 2019-09-20 21:05:44

I had two different things that caused that, both were fixed with programming. First, if your atrial rate goes too high- higher than your upper limit-   the pacer can't make the ventricles keep up, the pacer thinks we're in afib and puts us in an artificial 2:1 block. So, if the atria is doing 180, it paces the ventricles at 90. If we are in afib, that's a good thing because it keeps our rate down. If we are working out, it's like hitting a wall. As soon as the sinus rate comes down, it paces normally. Raising the upper limit fixes this only if your sinus rate isn't going higher than the new upper limit. So, if your sinus rate gets to 180, and the pacer is only getting the ventricles to 160, then the problem isn't fixed.

Second, sometimes my sinus rate randomly tanks. The pacer has a feature called rate drop response which kicks in and keeps the rate level if it drops suddenly. It can come down slowly after a workout, but if it tanks, the pacer kicks in and keeps it level. 

Ask them to put you on a treadmill while on the pacer computer. That is the fastest and most efficient way to fix this. They can watch what's happening real time and adjust the settings accordingly. 


by Pacedmyruns - 2019-10-01 03:10:19

Ask them to calculate your TARP! this is your 2:1 drop in half heart rate block. This can be lower than your upper limit if the TARP is not set right. So your max can be 160 but your TARP may be 130. So have them calculate that. I had that issue. You can exceed your max rate if your own heart can exceed it. Just because it's there doesn't mean you can't go beyond it. You certainly can. The pacer just won't pace you over your max rate. Mine is 185 and I can exceed 185 with my top lead bc I don't need pacing with running. But my bottom lead needs 100% pacing with running and it caps out at 185. But I don't drop in half at 185 I just cap there. My TARP is set that I don't 2:1 block until I'm at 220 

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Today I explained everything to my doctor, he set my lower rate back to 80 and I felt an immediate improvement.