Heart rate dipping when paced

So I am now 7 weeks post op.. I have noticed since I had the device fitted that whenever I am being paced my heart rate drops to the base limit, or near (50bpm) then suddenly increases again. 

I decided to do a bit of power walking today and my heart rate went from 108bpm to 50bpm within seconds. Surely this can't be good for my heart?

I was on VVI pacing but now on DDD as I was having terrible palpitations and dizzyness. Turns out that VVI pacing can cause heart failure symptoms and the EP was confused as to why I was even put on this mode. 

Anyway the long story short is I have had this dip in heart rate in both settings.

Any advice and is this normal?



VVI pacing

by AgentX86 - 2020-06-07 12:24:19

There is nothing intrinsically wrong with VVI pacing (I am because my left atrium is in fluttet anyway). If did cause heart failure it wouldn't be used. However It's certainly not useful for heart block and certainly not a 2:1 sort of block. The idea is to replace the AV node, not to eliminate iit. DDD is certainly more appropriate.

The dip in heart rate is indicative of your 2:1 block but I have no idea why it's still happening. Your pacemaker should have fixed this. I'd be in my EP's face about this.


by Savannah55 - 2020-06-07 13:33:54

Thanks for replying. I think she said I had pacemaker syndrome, which gives symptoms similar to heart failure. VVI pacing can cause pacemaker syndrome for those with heart block apparently.

I really dont understand pacing if I'm honest as everyone explains things totally different! But, my understanding is that when I go in to heart block, surely my pacemaker should be pacing at the rate my atria is going, not dipping to 50 something??

VVI pacing

by AgentX86 - 2020-06-07 19:41:18

Agreed, VVI isn't the best choice for heart block (as noted above).  DDD is much preferred.  VVIR has been used but it's certainly not optimal and reduced EF isn't uncommon.  DDD should at least be tried first.  Perhaps there's some reason it doesn't work well for some but I don't know why they would have used it without trying DDD first. It sounds like your EP wasn't the one making that decision.  Not good at all.

My point was that VVI(R) is useful for other electrical issues.  For example, I have SSS and an AV block intentionally done becuase I have highly symptomatic atypical flutter.  AV synchrony was sacrificed for an elimination of the symptoms.  The atria are/were in constant flutter so weren't contributing anyway.  DDD isn't useful in this case because the intention is to cause AV dyschrony (not allow the flutter to get through to the ventricles).

Yes, your ventricals should be following your atria and you shouldn't see the rate fall but it sure sounds like you're getting into the 2:1 block area again.  Something's not right.   I'd be calling my EP.



by Savannah55 - 2020-06-14 16:18:15

So since my original post I have had more of these heart rate drops and also a trip to A&E for pre syncope...

My lower limit was upped to 60bpm but hasn't made a difference..

After persuading them to fit me with a 24hr monitor it turns out that I am now experiencing some form of atrial tachycardia which my pacemaker cannot always track; so it either paces me really fast to keep up or doesn't know what to do so I get these drops.

My consultant is calling me Tuesday to discuss the holter and the pacing clinic made some adjustments to try and help my symptoms, but by the sounds of things it will either be meds or an ablation !


by Gemita - 2020-06-15 17:05:19

Thanks for the update. I think many of us feel that our PMs fall below the minimum rate sometimes even though our doctors say it is not possible.

i have atrial tachy arrhythmias so will be interested to hear what your doctors have to say after analysing your monitor data.  


by Savannah55 - 2020-06-16 10:14:01

Gemita I spoke to my consultant this morning on a what felt like rushed call. He wants me to start taking Bisoprolol and see how I get on. If that doesn't help then it will be EP study and ablation.

Also mentioned MVP needs turning on or off (I can't remember which) as I am very sensitive to pacing and this should help the dizzy spells. 



by Gemita - 2020-06-16 19:37:30

Thank you for the update.  Funnily enough I am on Bisoprolol and had an EP study but declined an ablation, preferring the option of pacemaker.  Hopefully he will start you on a low dose of Bisoprolol and this may be all that you need to feel better.

MVP = managed ventricular pacing - I would think it needs turning on to "prevent" unnecessary ventricular pacing although not 100% sure what he told you because your pacing requirements will be different from mine.  I see you have 2:1 AV block and intermittent permanent block.  I have tachy/brady syndrome and lots of atrial and ventricular arrhythmias - pretty nasty stuff sometimes when my Medtronic PM automatically switches me from AAI mode (pacing solely in right atrium) to DDD mode (pacing/sensing both right atrium and right ventricle) until arrhythmia ceases when it switches to atrial only pacing again.  What a RELIEF!  I hate it when my dual chamber pacemaker switches me to any form of ventricular pacing/sensing when it detects a fast atrial arrhythmia like tachycardia, flutter or AF and cannot wait for it to switch me back to pacing in my right atrium alone.  We are sensitive aren't we Savannah !

I am sorry your cardiologist's phone consultation felt so rushed.  I know exactly what you mean.  I can sense straight away when they are pushing to end the conversation.  My last phone consultation with my cardiologist was quite the opposite for a change - he gave me 30 mins of his time and seemed really interested in what I had to say

You know you're wired when...

You can finally prove that you have a heart.

Member Quotes

My muscles are very sore but each day it gets better and my range of movement is improving.