Rapid BPM drop during exercise

So I'm experiencing a rapid drop in rate when I start to get my BPM up during exercise. Once I get into the 110 ish range, I feel some PVC's (heavy beats) and then down it goes. It'll drop down to 90 most times and then others it'll drop hard down to about 70. Sometimes it'll recover quickly, and cruise at 110 again, but there's other times it'll stay low for minutes. Bottom line is I can't exercise and get into the cardio zone at all. I told this to the PA-C (not the doctor) today and her and the PM tech looked at me like I had a screw loose. I asked if the pacemaker could do that, and according to them it doesn't purposely drop the rate down for anytihng, so they honestly didn't have a clue. I'm going to get a monitor later this week, of which I had to suggest, and I'm hoping it'll show them (and me) what's going on. My theory is that my Atrium is loosing it's marbles for some reason (sick siuns) and stops proviiding a pace signal for a bit, and since I'm now standing still the rate response doesn't do anything. I have second degree AV block, so my Ventricle is paced 100% of the time and my Atrium seems to be providing the pace to the PM most of the time, but maybe not so much under those conditions. But I would think that the pacemaker would sense a drop in signal and instantly pick things up at that same rate. Heck I don't know! Anyway... if anyone has any thoughts, I'm all ears! Tim


How are you counting your heartbeats?

by AgentX86 - 2020-05-12 22:33:16

If you're using something like a sports watch or even counting yourself by feeling the pulse in the wrist, you may be miscounting wildly.  PVCs will easily throw off these methods because the "missing" or "short" beat won't be felt but it's there.  You need to count by feeling either your carotid (neck) artery or femoral (groin) artery.  An EKG will probably work but a pacer can throw these off too.

It's not you, it's *them*

by crustyg - 2020-05-13 03:35:11

You've described a phenomenon that's sadly quite common for some athletes with PMs.  Of course no-one programs the PM to cause this, but it *IS* directly caused by a poorly set-up PM.  It's very likely that a safety mechanism in the PM is detecting some PVCs and this crosses a measurement threshold in your device and it reduces pacing rate (the PM is trying to avoid you being driven into VTach, or possibly your atrial lead is detecting retrograde activity from the ventricles and this activates the anti-PMT feature).

I don't think you're mistaken that your HR drops suddenly - this is entirely possible if the PM protection algorithms kick in, and in any case you know how it feels when you are exercising and your heart output suddenly drops and you feel terrible.

You need to bypass the folk who think you are nuts, and explain what's actually happening to (ideally) a combination of your EP doc and the manufacturer's rep (if (s)he is any good - they aren't all) and then the penny will drop and they will make the necessary adjustments to reduce the chance of the protection mechanisms being activated.

Best wishes.


by Gemita - 2020-05-13 07:36:01

are very common with arrhythmias and even benign ectopics like PVCs and PACs can do it for me too Tim.  And yes, I get the same blank looks from my pacemaker technicians and EP who reassure me that my heart rate cannot fall below the set minimum (in my case 70 bpm) but this is not what it feels like to me.  I know when my heart rate is steady and well up and I know what it feels like when it collapses to extremely low levels and it can still do this and stay at low levels for 10 mins or so or longer when my arrhythmias hit, so it is not my imagination.

In your case a sudden drop from say 110 bpm to 70 bpm is going to make you feel absolutely awful.

A monitor is the way to go to have a look at what is happening to your heart rate and rhythm during exercise.  Do you have an arrhythmia like Atrial Fibrillation which can cause such sudden bpm rises and falls??  I do and my pacemaker has a very difficult time managing with blood pressure all over the place too.  I am afraid and I dont want to depress you, but Atrial Fibrillation is all too common in endurance athletes.  It is a price we may have to pay if we push ourselves to our limits.

Like you Tim, I am looking for answers and adjustments to my pacemaker to correct these sudden heart rate falls, so if you learn something, please post.  Thank you


by tapeterson - 2020-05-13 08:14:53

Thanks for the super feedback and supporting my thoughts. I've read other posts on here that also say that the PM can react to an irregular rythm and that the rate can drop due to this, and can't for the life of me understand why my tech and EP seemed clueless about this. He even saw evidence of the PVC's in the interigation. Well I'm sure that wearing the monitor will shed some light on this real quick, and between now and then I'm going to beat on the doctor and technician a bit to maybe get some better answers.


Here's another thing I mentioned that my tech was clueless about. I've read that the PM can adapt it's setpoints based on your lifestyle, so basically move values so it's not pacing when it doesn't need too or something like that. I believe this is for the RR rate response and that you can have it in "manual" mode or "auto", but again my tech was saying that the only way values can change is by him doing so. I'm going to read through the manual again to verify this before I go spouting off, but again I'm certain that I've read this in posts.


by Tracey_E - 2020-05-13 10:27:09

Only one pacer has a rate response that learns you, I think it's the Soren. It's called CLS (closed loop system). Most pacers don't have rate response that's that smart. Some of them sense movement, some sense breathing. 

The monitor should show if you are pacing when the drops happen. I have that, my rate randomly tanks when I work out. The pacer can absolutely be programmed to prevent this! My rate can come down slowly on its own but if there is a sudden drop, the pacer will kick in and keep it level. 

Tracey_E reply

by tapeterson - 2020-05-13 11:08:18

Hey Tracey_E,

So I have a Medtronics Azure XT DM MRI SureScan and it has a feature in Rate Responce called "Rate Profile Optimization" and with that turned on it automatically adjusts the rate response associsated the ADL and UR, which are the "setpoint" values. These range from 5-80 for the ADL setpoint and 15 -180 for the UR setpoint. The other ADL and UR responce values are fixed and set by the technician, and for me he has the ADL rate at 95 and response at 3 and the UR rate is 130, with the repsonse at 2.

Here's another tid bit of information. I just worked out and had no drop outs! I even had it pegged at 130 for a while, and of course I felt NO PVCs ... go figure LOL! So now I'm definitely convinced that the PVCs are whats causing the drop outs, or at least is realted to them. Anyway it was a great, near perfect workout in my mind. I did 30 minutes of weights and kept my rate between 115 and 130 the entire time. Crazy!!!







by Pacedmyruns - 2020-05-18 01:57:03

Have them calculate your TARP. TARP is what will cause you to go into 2:1 block at higher rates. Happened to me in the beginning.  This is common with exercise if your PM is not set up for high rates. It's called upper rate behavior.  So basically your running along at 150 and your rate drops to 75.  The pacemaker will only pace every other beat because it's told too. If your paced 100% in the ventricles, this setting is super importnat.  They need to make sure it's greater than your max HR allowed. So if your max is 160bpm, your TARP needs to be higher than 160. My max is 185bpm and my TARP is 222bpm. I will never hit 222bpm or even really 185bpm much.   Next time you go in, ask about your TARP. Then ask what your max HR is for exercise because when you pace mainly in the ventricles, you will not go above your max unless your own heart can go over the max.  Let me know if you have any other issues. Took me 10months to get my PM set up for exercise. 

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