Any runners on here to explain ?

Rate Response

by Selwyn - 2021-02-07 15:16:53

Hi,

It sounds that your rate response (that bit of your PM that increases heart rate with exercise)  and upper threshold limit is set too high. To answer your question, I believe the settings are artificially increasing your heart rate inappropriately, especially this is the most likely situation if your pulse is regular at this high rate. 

You can vary the onset and slop of increase for the rate response- a lower setting will mean that the heart pacing rate increases at a slower rate with exercise. 

Once you reach the upper rate limit ( this can be set variably according to your usual  exercise) the pacemaker will max. out. If you have your own natural pacing  more or less intact, this will take over as it does naturally once your need for a rapid heart beat are met. 

What to do?  I would phone up your pacemaker clinic and speak to one of the techs. They will be able to get you back in and tweek your settings. A lot is about them understanding your lifestyle. Not everyone is a couch potato!

I have recently got my lower limit raised to help with going up stairs, and also I get  some postural dizziness. The new lower limits helps.  I had a chat with my consultant last week about my inability to exercise due to shortness of breath. I know from my Kardia monitor my heart rate is maxing out at 115 on exercise.. Apparently, they have set my PM's upper rate limit to 115 bpm - my consultant says they will get me back in to raise the limit [something of the reverse of your problem].

Hope this helps- phone your friendly PM dept. 

Not sure I agree

by crustyg - 2021-02-07 17:16:04

I don't think you've provided the key information to allow us to be sure - and I'm too lazy to go through *all* of your previous postings to be sure.

What really matters here is your exact pacing mode. I'm not sure that you have Rate Response enabled - why would you with incomplete HB - you even say your SA-node is fine.  You mentioned in a recent post a clever Medtronic pacing mode that switches between AAI and DDD if it detects too long an interval with no Vent-activation.  IIRC you've now had that enabled.

So, *IF* I understand you correctly, all of your heart rate is controlled by your SA-node.

However, I would take issue with your analysis "am [I] going to max my heart rate out at a running pace that is extremely slow", when you report a low-intensity (for you) exercise producing a HR of 165BPM and a maxHR of 185BPM at an impressive 6min-mile pace (long time since I could manage that).  If your HR is indeed all controlled by your SA-node there may be plenty of effort required to get you up to 185BPM and keep it there.

You've had 3months off, so you're a lot less fit than you were.  And you're worried about a HR that's well below a rate that you were happy to have 3months ago and you're in your 40s.  So what?  I imagine you running a 10k in 35min or so, with a sustained HR of 185BPM and not worrying for a moment.  Now, if you're not careful, you'll be well on the road to becoming a cardiac cripple, always worried about your heart.

Stop fretting over the numbers, and listen to your body.  I'd kill to be able to run even 7min mile pace now and have it feel easy, and for you this is a great indicator of your previous level of fitness returning.  Enjoy it.

On the other hand, *IF* you have RR enabled, then apart from the obviously trite response of 'Get it turned off, you don't need it', then it needs to be tuned for you.  This forum is littered with posts from runners and road cyclists who've had to endure months and years of incorrectly configured PMs for their athletic lifestyle.  AFAIK, all EP-docs leave the twiddly bits of PM settings to factory defaults until some weeks after initial implantation - and many never revisit these settings.  Mine was specifically tuned for road cycling - but with SSS+CI I need the Minute Ventilation feature and that *has* to be tuned to be useful and safe.  Running - I was able to take the factory defaults from the start and haven't needed them changed.

Send me a PM if this doesn't make sense, or you want to share more detailed information.  Or just shout at me.

Thank you both

by quikjraw - 2021-02-07 17:43:09

I guess I need to ring the hospital up and ask if RR is switched on. If it is I will ask them why.

Obviously I am hoping it is simply the pacemaker that is doing this rather than my heart.

Crusty I think you may have misunderstood. My heart rate for the remainder of the run today was 175bpm at 10 minute/mile pace.  That is very high for that pace for anyone never mind a seasoned runner like me. :) 

I agree

by crustyg - 2021-02-08 03:19:19

It does seem unnecessarily high.

When first paced I was extremely anxious to avoid being overpaced and causing more damage.  Over time, despite long periods at or near maxHR on a road bike (3-4hr), my total time in each decade of HR (50-60, 60-70 etc.) is overwhelmingly in the bottom two decades - i.e. under 70BPM.  Which makes sense, given how many hours a day we sit and eat and sleep.  And my EP doc wasn't the slightest bit worried about long spells near maxHR - 'A Bruce protocol every weekend' were his words, as he explained that he couldn't see any indications suggesting ischaemic heart disease.  And if the heart can take it, then it's probably not worth worrying about, so I stopped worrying.