Low heart rate with pacemaker

I received a dual lead pacemaker at the end of February this year for intemittant complete heart block. I have had a few episodes of SVT and atrial tachycardia since then which have improved after eliminating caffeine. I take 25mg of metoprolol tartrate daily. Today my fitbit recorded a few short episodes of a 48 beat per minute heart rate.  My heart rate has not been below 60 since the pacemaker. I'm not sure what the settings are.   It was the fitbit that prompted me to go to the ER when I developed heart block without realizing what was happening,  but it could also be a false reading I suppose.  What could cause a drop in heart rate when I am paced? I did message my doctor but haven't had a response yet.


5 Comments

Fitbit

by AgentX86 - 2023-07-11 00:17:32

Fitbits aren't accurate, particularly if there is any arrhythmia in there.  They will read very low if there is any irregularity in the pulse. You might be throwing some PVCs or PACs that will drive the measured rate down.  In reality, the rate goes up (very slightly).

When I had one, it would tell me exactly when I when I had gone into flutter because the rate would instantly go from <60bpm to 80-85bpm (flutter is usually regular).  ER cardiologists would argue that it was a normal rate but I know my damn body! That wasn't my first rodeo. The ER cardiologist couldn't even see the flutter on the EKG.  My EP identified it in an instant.

My point is that the Fitbit won't tell you what's going on.  In fact, it will lie.  If you really want to know what's going on, get a Kardia Mobile.  The single-lead device is often on sale for <$70.  The six-lead for ~$120. The EKGs can be sent to your cardiologist, if he'll take it.My Kardia will give me an accurate rate, counting PVCs.

Low heart rate with pacemaker in the presence of an irregular arrhythmia

by Gemita - 2023-07-11 04:02:50

I would re-phrase your question to ask “What causes a lower heart rate to show on my home monitor which is below my pacemaker Lower Rate setting.  How can this happen?”

In the presence of an “irregular” arrhythmia (= a heart rate/pulse which is felt to be unsteady, as though it is pausing, slowing, stopping, starting, racing, thumping, fibrillating, fluttering), it can be very difficult for many home monitors to accurately assess heart rate.   Many monitors tend to give us error messages during an “irregular” arrhythmia, even my hospital grade BP monitor.  From my symptoms alone however and by feeling my neck pulse, I can get a better picture of how fast or irregular my heart rate really is.  

Always go by how you feel.  If I am tolerating these irregular heart rhythms well and they remain brief in duration, I can usually ignore them.  However when they are prolonged and I start to get symptoms like chest pain, feeling breathless, weak or even dizzy and faint, I usually know that my heart rate and rhythm are unstable.  So always go by how you feel, not by those home monitor results and always seek medical advice if you feel unwell until your arrhythmias have been identified and are well controlled.

As you will appreciate, in the presence of an arrhythmia, particularly an “irregular” one, anything is possible and pacemaker “timing” can sometimes be upset, so you are not imagining any of this.  PVCs (premature ventricular contractions), for example can apparently reset pacemaker cycle timing and delay atrial pacing, so there is a protective on/off detection safety mode. Also, some pacemaker settings/sensing can drop our Lower Rate Limit (Hysteresis for example) below the minimum lower set rate.  There is so much to learn about pacemakers and pacing in the presence of an arrhythmia which seems to be one of the most common reasons for reprogramming during any follow up. However we need to remember that a pacemaker was never promised as a cure for our arrhythmias.   Good luck and I hope things settle for you quickly

Monitor

by AgentX86 - 2023-07-11 13:28:58

It's not so much "trust but verify" rather "look and verify if result is interesting". Any monitor has to be checked against a manual check before it can be trusted. Every time.

From my experience

by PacedNRunning - 2023-07-13 02:10:49

These devies such as fitbit, apple watch, garmin etc. they do not read our slow paced beats correctly. When we are at our lower rate limit ie 60, the devices have difficulty reading our paced beats and therefore reads it falsely low. I wear an apple watch and fitbit and my lower rate is set at 50, I see less than 50, 48,46 etcc with apple I've seen the same and occsasional 40.  As long as it doesnt stay there long. You've verified it with a manual count, it's how it reads our beats.   Arrythmias and ectopic beats such as PVC's and PAC's can cause it to read falslely low as well. 

Thank you all again!

by Kmtd - 2023-07-13 11:25:20

I much appreciate the good and timely advice from all of you kind people. As a fairly nervous, new to all this person, this site has been a great help.  I did receive an answer to my inquiry to the doctor, and they suspect PVCs. 

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