Heart Rate Does Not Respond To Exercise

I am now 4 months post Biotronic implant, having been diagnosed (I believe) with SSS . Throughout my life I have been very active, including medium distance road-running (several marathons in my 50s and early 60s), cycling, weights, and more recently, recreational rowing (eights). In 2012, at the age of 80 I won the world indoor rowing competition (the "CRASH Bs" held in Boston MA) for my age group.

For most of my life my resting heartbeat has been in the order of 45 bpm; about ten months ago I started experiencing occasional dizziness but was assured by my GP that my heart was fine, so I continued with my regular exercise routine. However,  subsequent more intense/frequent bouts of dizziness led to an ECG from which it appeared that I was suffering from some aspect of SSS.  Reference to a heart specialist, followed by more tests etc, and I eventually found myself the proud owner of a pacemaker which, I was assured, would make me feel like my old self.
         The installed PM is set to maintain a minimum heart rate of 60bpm. The first problem I encountered was that with the PM this setting, I found that I was totally unable to sleep;  I enquired if the set rate could be lowered to approximate my long-term resting rate (45bpm) and was told that an overnight rate of 50bpm could be set: this made a marginal difference, but at the time of writing I have to take a sleeping pill to obtain 6 hours of sleep a night at best. I am given to understand that there is some agreement in the medical world that PMs may not to be set below 60bpm. Is this this the case, and if so, why?
From the standpoint of exercise, I have not been informed that my PM is set to any specific upper limit, but in the course of trying to achieve some level of fitness comparable to what it was shortly before my PM was installed, I seem to have lost all semblance of my previous endurance, and find that even short periods of medium intensity leave me panting for breath. My (admittedly somewhat inexpensive) wrist type HR monitor indicates that I can rarely reach a rate much above 80bpm, whereas until 5 months ago I could comfortably reach 130bpm. Or am I just expecting too much too soon?  



Rate Response

by Swangirl - 2019-03-08 22:09:26

Welcome to the club.  I am wondering if your device has rate response and if it's turned on.  Even with rate response higher intensity exercise is often problematic with a pacemaker.  That's my dilemma. I've had my PM tweaked by the EF but I am still breathless walking uphill when I used to be a runner.  Bottom line is you need to be the "squeaky wheel" and keep making inquiries until they give you the best your PM will allow.  


by AgentX86 - 2019-03-09 01:12:11

You'll never get a pacemaker to do as well as a healthy sinus node but since we'll never have one of those again, we're stuck hounding our pacemaker techs to get them to set our PMs up to our liking.  I wal quite a bit but mostly either on flat ground (indoors) or on a tradmill.  Stairs and long shallow slopes get me winded fairly easily.  The PM just doesn't respond well enough.  It could be  a lot worse.

As far as minimum rate and sleeping goes...  I started out at 80BPM and didn't like it a bit.  My EP said it had to be there for the first three months, then he could start setting it back.  After the three months I complained about not being able to sleep with it set to 80, so the tech set the PM to 70bpm day and 50bpm night.  The 70 didn't work out so well (PVCs) so they increased it back to 80 (still 50 at night - it's a pretty wide difference but feels a lot better, except if I have to climb any stairs.

PMs for Athletes

by KonaLawrence - 2019-03-09 01:38:00

Aloha Davecarol,
I paddle outrigger canoe (6 man crew) year around and race competitively during the summer months. I've had a Medtronics PM over a year and had may problems initially with it supporting my exercise.  The standard routine is a PM checkup at 30 days, 90 days, then annually.  I requested and got adjustment, after adjustment, after adjustment.  Eight appointments in the 1st nine months.  Biotronik is suppossed to be a better PM for athletes.  If your PM settings are the problem, you can get them changed.  Just keep asking & getting adjustment appointments.
My advice is to spend a lot of time with "Dr. Google" to learn about the options with your PM.  Then when (not if) you go in for an adjustment, you can talk their language and request specific changes.
In my case, I tried Rate Response Off and ON (better).  I had my lower and upper rates changed multiple times, finally 55 and 145.  I had changes to my Rate Response, Sensitivity Level, Response threshold, Rate Response Optimization and many other settings.  There are lots and lots of settings.  I think PMs are designed for more-or-less sedentary folks so athletes have to get special adjustments.  
Good Luck, Lawrence



by IAN MC - 2019-03-09 14:34:46

I am cønfused. In your bio you state that you have a Medtronic PM yet in the text above you say you have a Biotronik.

Assuming that you don't have one of each, what make do you have ???

Seriously, the two makes are fundamentally  different in the way they increase heart-rate in response to exercise which is the subject of your question.



by DaveCarol - 2019-03-09 16:00:29

Thank you for pointing out the discrepancy between my bio and my text. I have corrected my bio to show that I have a Biotronik PM installed.

I would be interested to know how this type of PM responds to exercise, and if feasible (and appropriate) how to modify that response to the types of exercise in which I indulge.






by IAN MC - 2019-03-10 08:21:14

Biotronik pacemakers claim to be better than Medtronics if you are "chronotropically incompetent" and are unable to raise your HR adequately when you exercise.

Medtronics sensors respond only to movement / vibration to get your HR up . One drawback of this is that they misinterpret vibration not connected with exercise such as a bumpy car ride and they may send up your HR when you don't really need it.

Biotroniks rate response depends on measured " impedance" which loosely can be described as how difficult it is for an electrical signal to be sent/received by the pacemaker.

When you exercise your heart should go faster but even if it doesn't it may contract even more forcibly to compensate for the lower heart rate. Your Biotronik PM ( if you have Rate Response switched on ) detects the subtle change in circuit impedance caused by the increased contraction and decides that you have started to exercise; the result  is that it will increase your heart-rate.

Biotronik terminology is to call this  C.L.S. ( closed loop simulation ) and it certainly sounds as though you need the CLS sensor turning on.

One claimed advantage of the C.L.S. sensor is that it will also increase your HR in moments of stress/ anxiety for example if you are suddenly attacked by a zombie on a dark street ! In other words it is more physiological in its response than are other makes of pacemaker.

But at the end of the day it doesn't really matter how your RR function works. All that matters is :-

Do you have a Dr / technician doing the adjustments who REALLY understands Biotronik pacemakers and how to adjust them to give you back your optimum exercise performance ?  Do you ?

Best of luck





by DaveCarol - 2019-03-13 17:35:50


Thank you for your very prompt and very constructive comments, thanks to which I felt confident enough to go see the Pacemaker Clinic, located in my local hospital, to discuss several of the points you mention.

The technician I met certainly gave me the impression that she was very familiar with both the operating features, and the feasibility of the adjustment thereof, for the Biotronic Edora 8 DR-T PM installed in my left shoulder some 4 months ago.

I explained to her the problems I had encountered in relation firstly getting to and staying asleep, and secondly to the slow response of the PM during exercise. As far as sleep was concerned, she felt that that there was little she could do beyond dropping the basic rate a little.With regard to the slow response rate during exercise, using the "Rate response" function,she reset a range of available rates and responses, including a "Max. activity rate" (120 bpm), an "Upper response rate 130 bpm), and a "Mode switching rate" and "Intervention rate" (160bpm).

All this, together with a bunch of other associated data, which the technician had used in re-calibrating my PM, she provided to provided to me on a printout.

I was impressed! I'll see how it all works during my next serious bout of exercise tomorrow.





My lower limit is 45

by Tiffsterty - 2019-04-13 08:41:16

My lower limit is 45 but I’m not symptomatic so I’m not being treated for my low heart rate yet. Mine does not have a night mode. My max is 185. Like someone else said. Google about these things and how it controls our hearts. I’ve had many adjustments and we are now finally narrowing down my AV delay. Seems that has helped me the most with breathing and stamina with exercise. It’s just a matter of finding the right number 

My lower limit is 45

by DaveCarol - 2019-04-24 12:23:43

Thank you for your helpful comments!

One question: You mention "AV delay adjustment"; I can find no mention of this I the printout of my pacemaker parameters. Could you explain what this refers to?


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