Hi all,

a quick question before I go to my doctor about this. But when I was in hospital one of the reasons why I needed a pacemaker is because I was bradycardic. However recently I've been tracking my sleep via my Fitbit and my heart is still dropping to 41-42 bpm. (Before the pasemaker it was dropping to 36-38 bpm) My resting heart rate is 52-56 bpm naturally too. I thought the pacemaker would speed this up, obviously I need to have a check up and see how my heart is doing (last one the said was absolutely fine about 6 months ago and told me to go back in 2 years. But shouldn't the pacemaker stop me from going into bradycardia? Or is it the case that I'm bradycardic and that is it? Basically, should I be worried? 

apart from my heart rate dropping during sleep (which I don't notice), I have no other symptoms and my pacemaker is working perfectly. I am just worried because I don't sleep well, don't feel very rested and I feel like it's linked to this.





Double-check your data

by crustyg - 2020-05-11 08:25:54

I'm afraid it's more likely that your Fitbit is getting your pulse wrong than the PM/leads aren't working correctly.

Find a nice, easy to feel pulse on your body - for many the big pulse at the groin is easy to feel and lying in bed no-one will misunderstand what you're doing.  Count the pulses for at least 30seconds and then use that figure to determine your resting HR.

*IF* this is lower than the minimum HR that your PM is set to deliver, call your EP next morning, as there's a problem.  If not, then you've just proved why some self-monitoring kit isn't as useful as you might have hoped!


Sleeping heart rate

by Selwyn - 2020-05-11 08:58:34

Pacemakers are designed to save on the battery by having a day/sleep cycle. As long as you are symptom free during the day, a pulse of say 40-50 in your sleep is acceptable ( if your Fitbit is accurate). A sleeping heart rate is roughly 20 less than a day time resting heart rate, depending on your age, fitness, etc.  Day time resting heart rate is usually set to 60 for a PM.  The day/sleep cycle can be adjusted as an automatic function of your PM ( depending on the type). 

Battery conservation is an important function of pacing. 

Day/Night rates are not a feature of all PMs

by crustyg - 2020-05-11 12:26:59

My Accolade doesn't have this feature.  My lower rate limit (LRL) is *always* 50bpm, day and night.  A much bigger controller of battery life is pulse-width combined with pulse voltage.  Ideally a good lead will capture with a tiny impulse - perhaps 0.4ms at something like 0.7V.  Under this load the pacing output is nearly the smallest drain on the battery! 

Increase the pacing width by 50% and the battery drain goes up quite sharply, ditto the pacing voltage.

AFAIK, many PMs provide a day/night LRL so that they deliver a reasonable paced rate during the day without needing to resort to Rate Response (and all of its complications) and still enable patients to drift off to sleep with a low(ish) HR.

Low pacing rate

by AgentX86 - 2020-05-11 13:04:34

As others have noted, FitBits and other watches that use the Pulse-Ox type sensor cannot be trusted.  If the fit is too loose or the watch slips slightly, the numbers can be way high or low.  As Crusty pointed out in his first note, the only reliable point to monitor your pulse is in the femoral artery, the large artery that supplies the leg.  It's the main branch of the Aorta, the artery coming out of the left ventricle.  If you're having PVCs, the FitBit will surely be fooled and you may not be able to feel the "missing" beats in your wrist, either.  These "missing" beats aren't really missing but weak enough that you may not be able to feel them in your wrist.

As noted also, some PMs have a night mode but it would be unusual to have it enabled without your knowledge.  Usually you have to ask for it for your EP to turn it on.  They need to know your normal sleep patterns (it's set by its internal clock).

Quality of sleep

by Gemita - 2020-05-11 13:17:41

Hello Callum

I too suffer from bradycardia and my doctors know that I feel better during the day and sleep better at night with my heart rate at 70 bpm. Yes it would be rather high for most folks particularly at night but not for me.  If it drops below 70 bpm I am very prone to getting slow irregular ventricular and atrial ectopic beats which usually develop into more troublesome arrhythmias that would keep me awake all night.  By keeping my heart rate up, I can usually keep a regular heart beat going and feel so much better.

I would ask your doctors what your heart rate is set at at night and if it is possible that it is dipping below this rate ? You say you don’t feel your heart rate dropping at night and yet you say you don’t sleep well or feel well rested during the day so maybe your pacemaker is failing to meet your requirements during the night ?  You could additionally ask your doctors about getting tested for sleep apnea and whether you could have a home sleep study performed to gather further info about your sleep patterns.

I agree about some of the self monitoring equipment that is available.  When our pulse is regular, it can usually give a fairly accurate reading, but throw in a few irregular, slow or fast heart beats and the home monitors may not be able to cope or give accurate readings, so taking the pulse manually is a good idea.  I also have a good quality blood pressure monitor which confirms what my blood pressure and heart rate are doing during periods of “irregular” rhythms but it certainly isn’t 100 per cent accurate.  When I get irregular ectopic beats these often cause a slow, weak pulse which is hard to detect manually or with home monitoring.  During these times I certainly feel my pacemaker is not performing well (not keeping the 70 bpm pacing) or my heart is not responding well to being paced.  However my doctors keep reassuring me that my pacemaker will not allow my heart rate to drop below the set minimum of 70 bpm but I am convinced that this is still happening because symptoms of near syncope and weakness develop.  I shall be speaking to my doctors about this.

As far as battery conservation is concerned, I agree it is in our best interests to preserve battery life for as long as possible but not at the cost of having a pacemaker which fails to meet our needs.  I hope you get answers from your doctor Callum.  Good luck

FitBit Data

by alanr1303 - 2020-05-12 06:12:27

As crustyg said the problem is probably with the fitbit.

When i was diagnosed with bradicardia 18 months ago I spent 3 days in hospital waiting for my pacemaker to be fitted. I was hooked up to a heart monitor which showed my rate as 30-35 BPM, my fitbit consistently indicated double this value ( 60 - 70 ).

I think fitbit is expecting a "normal" heartbeat pattern, which may not be present while the pacemaker is working.


Arrhythmias can confuse meters

by Protimenow - 2020-06-28 15:32:59

I had some weird arrhythmias. They were so strange that even the blood pressure machines in the hospital were often unable to get an accurate heart rate. The electronic machines expect rather consistent heart rates - and arrhythmias can throw then way off. 

I have a pulse oximeter that the hospital gave me. I have a BP monitor, and I have a Fitbit. Even now (with a PM), my arrhythmias are still frequent and strange enough to throw these devices off. 

Strangely, in spite of showing HRs in the 50s, the Fitbit app shows a resting heart rate of 73. My PM is set to 70. 

Also, rather strange, was the climg in resting heart rate on my Fitbit app - post PM, it slowly rose from 50 to 70. I sort of expected that it would jump to 70 right away -- why did it take a week to catch up?

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