Pacemaker in hot weather

I feel like my medtronic pacemaker is less effective in very hot weather. It's working, but I seem to have more trouble walking upstairs outside than in moderate weather. Does that make sense according to way Medtronic measures needs?


It is the patient who may not tolerate the heat, not the pacemaker

by Gemita - 2023-08-15 04:41:55

Lisa, you state, I feel like my medtronic pacemaker is less effective in very hot weather. It's working, but I seem to have more trouble walking upstairs outside than in moderate weather. Does that make sense according to way Medtronic measures needs?

If I understand your question correctly, I do not believe your statement is completely accurate.  It is the patient who is less able to tolerate the hot weather, not the pacemaker.   The heat doesn’t affect the pacemaker, but it does affect us.  We slow down, we may struggle to exercise, to sleep, to eat and may easily become dehydrated.  We may also notice an increase in our electrical disturbances during hot weather and if we have heart failure or other serious health conditions, these may all deteriorate too.   Our needs for more energy may then increase and our pacemakers may need to work even harder to keep us going.   Does that answer your main concerns?

If you are struggling, it goes without saying that you should speak to your doctors for advice.  It could also be that your pacemaker settings might need some adjustments too.  I hope you feel more comfortable soon.

hot weather

by Lisa Michelle - 2023-08-15 05:50:03

I appreciate what you are saying and it all makes sense. I'm just wondering if the pacemaker has the ability to sense the stress on the heart of the hotter weather and adjust for it in the way that it senses the increased need for pacing when walking vs resting. I have heard some pacemakers have different ways of sensing needs (such as oxygen levels or other measures) and I'm wondering if Medtronic has this ability. Not that I'm about to change it at this point, but I just am trying to understand my abilities better particularly in different situations like extremely hot weather (close to 100 F).


by Penguin - 2023-08-15 06:09:22

Hi Lisa, 

This link contains an explanation of how the activity sensors in Medtronic devices sense movement and increase heart rate. To answer your question - the device doesn't specifically sense 'heat' but it may sense when you need extra assistance * depending on programming.

You would need to speak to your pacing clinic to understand how your pacemaker is programmed currently and whether or not your current settings permit this extra assistance or not.  As stated by Gemita your settings may need to be adjusted to assist you further if you are struggling during hot weather.

* However, your pacemaker will not be able to stop your blood vessels dilating in hot weather and this may lower your BP.  More water and snacks with some salt - (pretzels were suggested to me) by members of this forum.  These items may help more than setting adjustments if the problem is dehydration or lower BP in the heat. 

** I don't believe that Medtronic have minute ventilation (the breathing related rate response algorithm that you allude to). I think they just use accelerometers - but check!

* Amended 

hot weather

by new to pace.... - 2023-08-15 06:09:48

I agree with all that Gemita said above.  You need to make sure you are drinking plenty of water when out in this heat. Better yet only go out when it is cooler if possible.  Your pacemaker  should  keep up with you.  

new to pace

Medtronic pacemakers

by Gemita - 2023-08-15 06:18:45

Yes Lisa, our Medtronic pacemakers have sensors.  For example when I am dehydrated and suffering from heat stress my heart rate may drop and the pacemaker will step in and keep my rate no lower than my set lower limit.  The pacemaker cannot control an increase in heart rate though which can also occur, nor can it control blood pressure either high or low both of which will adversely affect our ability to exert ourselves in hot weather.

Have you got a copy of your manual where you will find all the features of your particular model of pacemaker to see what special features it has. I have rate response switched off but you can ask more about this feature if you have chronotropic incompetence (inability to naturally increase your own heart rate without pacemaker support). 

thank you for the helpful responses

by Lisa Michelle - 2023-08-15 06:22:27

I will take a look at the link sent and see about getting a manual. I wasn't given anything specifically from Medtronic. 

Pacemaker sensing

by AgentX86 - 2023-08-15 11:18:09

Pacemakers, Medtronc in particular, can't sense anything but motion, specifically vibration, like footfalls (and bumpy roads, and shaking something with the left arm 😣). They have no contact with either blood or the nervous system.

As others have said, the rest of your body can.  Dehydration, the loss of electrolytes (sodium, potassium, magnesium) can cause big trouble.  This is really easy to do in hot weather.  Keep careful tabs and eat food high in these elements, unless your doctor tells you to avoid salt.  You still need it but be careful. Do not bother with sports drinks.  While they're full of sodium and sugar, they have almost none of the other elements.

The loss of blood volume because of dehydration is a problem, too.  Drink a lot of water.  If you're concerned, go by your weight.  If you've been outside or sweat at all, weigh yourself.  If there is any loss during the day you need water ASAP.  A pound of weight loss is about a pint of water.  A kilo, a liter. Take into account food and you'll get a very good idea of hydration levels.  Also be careful that you don't drink too much.  Water will wash these elements out through the kidneys.  In addition to short-term gain/loss of weight, be aware of your peeing.  It shouldn't change.  If you pee less, or it's a darl color. you may well be in danger of dehydration. Too much and you could wash electrolytes out of the system.  There is a fairly large gap in the middle that's normal but just be aware of this built-in alarm.

Your body will do everything it can to keep your core temperature regulated, including dilating surface blood vessels (particularly in the head).  This acts like a radiator to shed heat.  Heat stroke is where this effect reverses and you gain heat because the environment is adding heat through these mechanisms instead of losing it (core temperature increases).

Another major problem is that you just don't feel good in hot weather so you blame it on something.

It's probably a combination of everything above. But it's not going to be your pacemaker, at least directly.  It's not going to change the rate.  Perhaps it should but it doesn't know that.

The big thing is to drink water (not too much) and keep cool.  Once your core temperature gets out of whack, the body has a hard time getting it back into regulation. Pretty much everything it does makes it worse, rather than better.


by USMC-Pacer - 2023-08-15 14:18:22

Do you monitor your heartrate (HR)? Hot days can definitely raise your HR. If it raises it enough and puts you at your PM upper limit, you will feel it. You didn't state your symptoms so I'm not sure if this applies. It would be easier to hit that upper number in the heat depending on what it is. Default is 125bpm for most units I believe. If that is the culprit, it is an easy adjustment for your clinic. They have upped mine several times as I'm always pushing it to that limit. It's also known as Max Tracking Rate (MTR). When I used to hit mine, it would cause a strange sensation - nausea, shortness of breath, and leg weakness. Just my random thoughts. I hope you find the culprit :)

excellent random thoughts

by Lisa Michelle - 2023-08-15 15:38:11

Those are exactly my symptoms when going upstairs in extreme heat. I'm a tour guide and I do the same route all the time so I can really see the differences in how I'm doing on different days. I will talk to my doctor about this. I will get a Fitbit or something similar. Any recommendations on an effective brand of HR monitor?

Heart rate monitor

by AgentX86 - 2023-08-15 16:31:53

It's not good to continuously worry about your heart rate.  It may turn into a compulsive disorder.

That said, none of them will give reliable readings for everyone.  Some have found that some work for them but don't count on it.  If you have any sort of irregular heartbeat, cross off any with a pulse-ox style sensor. They're not all that reliable and are often read significantly off (I'll have two disagree by 30bpm).  These have green LED on the back to monitor the pulse.

The other style are the "electrical" or can do a single-lead "EKG".  Apple and the newer Samsungs fall into this category.  When they work, they're good but often pacing spikes throw them way off.  The're not intended for people with pacemakers but sometimes they work well.


by USMC-Pacer - 2023-08-15 18:49:05

I use the Polar H10 strap monitor. I read it via MapMyRun (UnderArmor) through my iPhone. I'm sure it's compatible with other phones or fitness watches like Garman, Apple, or Fitbit. It works perfectly for me and "usually" keeps me out of trouble, or at least I know when I'm getting into it :) I also use a Garman Fitness Watch. But, I find it lags, or reacts slowly to HR changes. The strap is instantaneous and accurate, at least for me. I haven't had any problems with it. Hope that helps..

Note: I made one change above... MTR is Max Tracking Rate, not limit..

Edited to add: Those feelings when I hit my MTR are do to a 2:1 block brought on by the device for prevent your heart from going too fast. If you have no other restrictions, your EP should raise it for you. When I hit mine when it used to be 130bpm, I'd get those feelings and my HR would immediately drop to 70-80 and then the crappy feeling...


by Penguin - 2023-08-16 07:50:12

Hi again Lisa, 

I've just had a read through your previous posts. This 'stairs' issue is clearly causing you some concern in your role as a Tour Guide in Israel.  I can understand how difficult it must be for you to work through that kind of heat. Not easy at all. 

Re: USMC's comments above. I see that you were going to have your MTR raised to 150 bpm approx 6 months ago  Was this done? You were also organising an MRI for sarcoidosis. Did you get any answers from this? 

I see that you've had previous replies (historically) from people with Medtronic devices expressing similar difficulties with stairs. This may be an aspect of your current device that is going to prove difficult to overcome without a change of device. If this issue is affecting your job you could take advice regarding the virtues / negatives of other devices with minute ventilation / accelermoters or both. 

In terms of setting adjustments it may be best to ask your pacing team to explain how effective raising your MTR further would be. Sometimes it's best to get a response straight from the professionals and to have them explain whether or not it will help you.   They will obviously know more about your particular cardiac conditon and any meds which may also have an impact on your electrolyte balance in the heat. Being based in Israel I imagine that they will have a great deal of experience with explaining the effects of heat on cardiac patients and what may and may not help you.  


MTR and heat

by Lisa Michelle - 2023-08-16 08:04:58

Thank you (and everyone) for taking the time to give such helpful and thoughtful answers.  After many months of struggling with stairs from August 2022 to Feb 2023 with the help and encouragement of this group, I had the issue resolved...I think they set tracking to 150 if I remember correctly and changed something else. It was a long journey because it seems most patients in the hospital I go to aren't in my situation which is completely PM dependent (complete AV block), without other heart issues. I am 52 and have a very physically demanding job. So my tech people haven't seemed to have explored this issue so much. When I finally went to a top cardiologist, he said of course it was a problem with the settings. As it happened, just before I reached that doctor, I actually prescribed for myself a stress test. The following day, they called me and said now they see what I was talking about and asked me to come in the next day to fix the settings. Once that happened, I was doing great! I felt like I was bionic and in better shape than before I developed a problem. However, in this hot weather, I seem to be challenged again with a settings issue, or perhaps that's just something that can't be fixed. 

The doctor actually did recommend additional changes but the tech people (and doctor at the hospital) didn't agree. I was happy with the dramatic improvement so I didn't push the issue. However, I think I will revisit my private cardiologist and the PM staff and see if they can do more with the settings. 


Just another thought..

by USMC-Pacer - 2023-08-16 13:41:37

At one point with my issues. The EP finally had me got on a treadmilll with all the monitors and a Medtronic Tech standing by. I did a fairly strenuous workout and they saw my issue. Aside from my MTR, they noticed my AV delay settings were off when I exercised. They adjusted those and it corrected that issue. Once they corrected those issues, I was good to go :)

Maybe you can ask your team if they can do that? Put you on a steep treadmill to simulate stairs and see what's happening. Good luck :) Hope the best for you.

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So, my advice is to go about your daily routine and forget that you have a pacemaker implanted in your body.