Pacemakers & Increased Pulserate During Exercise

[mountaindreamer]

Hi, I’m new here.

I’m curious to know if anyone else has experienced my current limitations with pacemaker programming during exercise, and if so whether they’ve found any better options.

I’m currently in my late 40s and have had 4 pacemakers since my mid20s - for rapidly developing 2:1 heartblock, which soon became total block. With no signals going through to my ventricles, my brain was firing my top atrial heart chamber to give “p waves” at the rate I needed, and the pacemakers were “relaying” these signals to fire the ventricles and give me a pulse.

I’ve never felt I needed to fully follow pacemaker workings and programming, but my first pacemaker basically halved my pulse rate during more intense exercise, because the time it was unreactive (to avoid getting double triggered by a later part of a single pulse cycle) meant that it would suddenly only respond to every other p wave. I was then “upgraded” to a model which could go to a higher maximum rate (189bpm), and the problem was resolved.

Rolling forward to my 4th pacemaker, and a return to mobility after many years of severe spinal problems, last year I discovered with a Fitbit heart rate monitor that I was struggling to get fit because this pacemaker was also halving my pulse every time I did any intense exercise. The device has now been reprogrammed to prevent that happening, but it appears likely that this halving has been going on for years, and probably for the pacemaker before this one too. (I don’t pass out when this happens, I just slow down a lot and struggle, so no one realised.)

Now the reprogramming has been done, however, it has become apparent that my “p waves” no longer behave consistently during exercise. Sometimes I may therefore get a high pulse rate, while a standardised StairMaster hill climbing exercise may at other times result in a gradually dropping pulse rate, which increases again when I’m slowing the machine down. Similarly, when hillwalking in the mountains, climbing a long steep slope can result in my pulse gradually dropping significantly (sometimes down to 70bpm), but then increasing again massively when I sit down to rest at the top.

With my “p waves” no longer apparently reliable during exercise, I am now instead relying on a crystal sensor within my pacemaker which responds to arm movement. This crystal increases my “p waves” when it sees my rate of arm movement increase. Sadly that is not too helpful for hillwalking (where the amount of exertion is no longer in proportion to the number of steps and arm swinging movements made). It is also really of no use to any poor cyclists, who don’t swing their arms at all...

When my cardiologist looked into this for me, I was surprised to be told I was an anomaly, and that unreliable “p waves” were never to be expected for me (not until I reached about 70 anyway, when I’m told it can happen to “normal” older people who don’t have congenital heart block). So I don’t know if it’s happened to anyone else out there too, or if I’m the only one. (If I’m the only one then I’m left wondering if it’s somehow the result of intense exercise resulting in my actual “paced” pulse halving for years...)

My cardiologist had hoped that a solution could be found to either reprogramme my pacemaker somehow, or to find some other option, but a year on seems to have him now sadly saying there are no options and I’ll have to manage with what I have. One thing I’d been hopeful about were sensors in pacemakers which responded to breathing rate and breath depth instead of arm movement rate, but I’m told there were tragically fatalities due to such sensors, so no manufacturers will be looking into them further.

I’d heard that some early variable rate pacemakers had a wrist device which could be used to manually adjust rate, so I can’t help wondering if that would again be possible, but I guess eliminating the possibility for “user error” is seen as highly desirable by companies these days, so I suspect that won’t be an option.

Has anyone else experienced these problems (eg cyclists or other hillwalkers), and if so have they been given any better suggestions?

[JonathanPittsCrick]

It is not unusual for people who develop heart block at an early age to progress to sinus node disease or atrial fibrillation later on, requiring reprogramming of their pacemaker so that it can "decide for itself" how fast the heart should go.

Your pacemaker uses body movement (not just arm movement) to detect exercise but everybody is different in how the movements relates to the intensity of exercise and also how fast the heart should go to feel comfortable. The pacemaker response can be optimised by undertaking a short walk at a normal and then a brisk rate and then adjusting the settings to achieve the correct result. With some pacemakers this only needs to be done once but with others you have to make a series of walks and choose the best settings by trial and error. Unfortunately it is not usually done in pacemaker clinics because it takes time.

There are some more complex types of pacemaker which use "dual sensors" to adjust the heart rate, one being body movement and the other, either breathing or the heartbeat itself. These can give a more physiological response, especially being able to detect the difference between walking uphill and downhill and also responding better to other forms of exercise like cycling and swimming. They still need adjustment in the same way to achieve the best response.

The response does not have to be perfect as a healthy heart can function over quite a wide range of heart rates with exercise and provided it is able to reach a maximum rate of 120-140 bpm (depending on your age) this should be enough to enjoy your hillwalking.

[mountaindreamer in reply to JonathanPittsCrick]

Many thanks for your reply. It’s interesting to hear this is quite normal to happen, having been told recently it’s not, as I was always told losing my natural p waves was eventually quite likely when my original pacing team fitted my first device. (It made me push myself to climb 21 000ft peaks in Nepal as soon as I got my upgrade, incase, as is now the case, I couldn’t later on.)

Without really understanding the ins and outs of programming, but finding that pacing technicians even in a specialist heart hospital still aren’t used to seeing many fitter patients (one told me I was the only patient they’d seen who had their device set to go up to the max rate of 175bpm), I’m not quite sure if my programming is already seen as being as optimised as possible. I had a treadmill exercise test done last year when they were reprogramming the device.

I would like to try and understand further if I can, so I know what is possible. As my cardiologist tells me nothing more is really possible, I’m a bit unsure on next steps. Perhaps I’m being a bit too unrealistic though. Having had my 2nd pacemaker take my younger pulse rate up to 189bpm, I’m now frustrated that I can’t reliably maintain nearer my current 175bpm max rate unless I run on the flat. (When my heart will happily maintain exactly 175bpm until I slow my arms down.) I’m a pretty fit hillwalker, so pushing myself to go uphill will usually get my pulse far higher than 120-140bpm when my p waves are behaving. Still, that’s better than when my pulse decides to drop to 70bpm during intense uphill exercise, even if it would slow me down a bit.

I guess, after spending years believing pacemakers don’t restrict my activity levels in anyway, I’m just frustrated to realise they now do.

If you have any further advice on what I should maybe be asking my pacing technicians about as far as programming, then I’d be very grateful to hear it.

I’m also curious to hear you still referring to people having dual sensors which respond to breathing. I’ve been told these are no longer an option due to fatalities in pacemaker dependent people. (I was rather confused by how that could happen, as I thought a pacemaker would still operate only between certain safe limits, whatever sensors it was responding to. Obviously I don’t want to be a guinea pig if being a fatality statistic is a risk though.) Do you know any current models like this offered by UK hospitals? I go to Liverpool for pacing, where Medtronic seem to be the main manufacturer they deal with. I believe they have already approached Medtronic asking about customizing me a pacemaker, or a software patch for the current one, but with no apparent success.

[JonathanPittsCrick in reply to mountaindreamer]

The dropping pulse rate that you describe during exercise suggests possible triggering of the automatic mode switch algorithm caused by exercise-induced AF, atrial over-sensing or setting the tachycardia detect rate too low. But it would also require that the rate response settings were very limited.

Yes, there are currently problems with the Boston pacemakers, made in USA, using breathing to control the rate and I'm sure that they are working on a solution to these. The other breathing controlled pacemaker is the Sorin (recently rebadged LivaNova Microport), made in Italy. The pacemaker that uses heart contractility "CLS" is Biotronik made in Germany. The other two American pacemaker companies, SJM (recently rebadged Abbott) and Medtronic use just the movement detector – they work pretty well when properly adjusted. Although they cannot distinguish between walking downhill and uphill it is possible to create a difference by adopting a specific movement pattern when walking uphill with an exaggerated swinging of the shoulders. Ideally you should attend the pacing clinic with your (loaded) backpack so that the pacemaker response can be optimised to the conditions where it is most required.

[mountaindreamer]

Thanks for your detailed reply. I’m sadly not sure exaggerating arm movement for uphill would work out too well for me, as I also have a temperamental C5-C6 neck fusion that doesn’t like me upsetting it. I guess that’s why my cardiologist was asking me how much I was able to move my arms and upper body. Perhaps alternative “safe” sensors may be a better option for me, if I’m allowed to have them considered. Thanks for giving me plenty of food for thought. It sounds as if I should ask my cardiologist and pacing technicians a few more questions.