39 yo, Active Runner with PM for sick sinus syndrome

Hi all,

I'm a 39 year old active person who's had a Medtronic PM for about 2.5 years. Long story short, was diagnosed with sick sinus syndrome and historically not had an issue elevating heart rate so just had the PM set to kick in at 50 bpm and had rate response turned completely off. 

Lately, I've noticed on runs that my heart rate will go to about 160 and then afater about first mile (~7:30 minutes) that my rate will start to slowly decline and by 15 minutes in I could be down in the 120s. We've made some PM setting changes today that I wanted to run by this group and also see if anyone else has had any similar issues since my main issue now is just helping my HR keep up the pacing that it should be doing while particpating in significant activity. As it stands now, I get severely fatigued and have to stop exercising/running once it gets into the 120s or teens. 

Setting changes are as follow: 

Rate Response: On

Activity threshold: High

Optimization: Off

ADL: 70 (changed from 95)

Upper Sensor: 160

Deacceleration and Acceleration: 1


Thanks for any input! 



Check out this thread

by ar_vin - 2021-04-15 03:11:28

And others like it. Especially posts by member frankmcw2.






that should help

by Tracey_E - 2021-04-15 09:07:40

Just turning on rate response should make a big difference! The other settings, it may take some experimenting to find out what works best for you. I'm not sure what all of those mean, but it appears to be fairly aggressive, so that rate response kicks in quickly. 

Do you typically get over 160 when you run?

Mine is also set to high, so it jumps up very quickly. This is great when working out but sometimes annoying when my rate goes up other times when I don't need it to, like if I jump up quickly to answer the phone I'll be breathless when I answer. I chose to keep it this way, having the response I need when working out is important to me so I'll deal with it the rest of the time. 


by quikjraw - 2021-04-15 11:21:45

Ryan if you go to page 80 of the guide in the link below there is a detailed explanation of all the settings and what they do. Some of them are a bit more complicated but others are very straightforward to understand.


Tracey - just picking up on your last point, what would cause the breathlessness with a higher heart rate than is needed, like when simply jumping up?

does too high a heart rate for a given exercise or task cause breathlessness?



by Tracey_E - 2021-04-15 12:06:45

breathlessness is from my rate jumping up quickly?


by AgentX86 - 2021-04-15 12:08:13

Yes, the same sort of symptoms can show from too much oxygen in the system and too little.  We all know that you can black out from too little oxygen but aslo black out (called "red out") from too much.  It's the reason that the atmospheic pressure has to be decreased when breathing pure oxygen.

It's my understanding that the body naturally tries to keep the pH (really pOH) at a constant. Breathing doesn't only bring oxygen into the system also expells CO2.  Which happens (more) depends on how much is in the blood.  Rapid/heavy breathing, as well as a higher heart rate, are the mechanisms for this.

thanks, Agent

by Tracey_E - 2021-04-16 10:40:51

I knew it was connected, but didn't understand what was behind it. 

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