Low rate set at 70 HR has dropped lower

Hi all, 

Looking for some advice please. My Husband has a Medtronic dual lead pacemaker inserted in January for Heart block. He also had an Ablation for Afib in March. We are seeing the EP tomorrow as we feel we need some questions answered, ie breathlessness, postural hypotension which seem to have worsened since these procedures. The last few days we have been monitoring BP/HR/symptoms more often in order to discuss with the EP. Today I believe John is having an episode of Afib, his heart rate is jumping around however my question is with his lower limit set to 70 his heart rate has dropped as low as 39 for a few beats and then climbs back up to high 60’s low 70’s. While John was napping I watched the finger oxygen monitor for probably 10 mins as an example over approx 12 beats his rate was:
Is this how a pacemaker should work or should it respond more quickly. 

As this is all relatively new to us any suggestions or insights would be helpful as we would like to be able to ask informed questions at the EP’s appointment tomorrow.  Thank you.


As you say, something is not right...

by crustyg - 2019-09-15 12:43:54

But you're seeing the best person tomorrow.

In general anyone with a dual-lead PM with heart block would expect to find that the box will drive the ventricle to keep at (or above, if rate response is enabled) the Lower Rate Limit - 70 for your husband.

Pulsox isn't a great way to monitor heart rate if there's Afib as some of the smaller beats can be missed (there's not a big enough pulse of blood to make a big enough difference in the light absorption so the gadget misses the beat.  Feeling for a femoral (groin) or carotid (neck) pulse is probably the most reliable.

The amount of blood ejected from the L ventricle will vary from beat to beat as there's no reliable filling mechanism (the atrial contraction): I don't know how effective your husband's atrial pacing would be at creating some sort of atrial contraction if the AFib has returned, but it *might* be that this atrial pacing is now less effective than it was, hence less filling of the LV and hence lower heart output (and less obvious pulses for the pulseox to monitor).

The breathlessness may well reflect less effective emptying of the L atrium (more back pressure on the lungs) *and* result in lower LV output, hence postural hypotension.  Often, lack of blood supply to the body also creates a sensation of breathlessness - odd but correct - with only minor reductions in %O2-sat.

Hope that helps, best wishes for tomorrow.

Asking the important questions

by Boneysjoint - 2019-09-15 13:27:47

Thank you, that does help. We both are happy John’s EP but sometimes we feel that unless questions are asked an explanation isn’t forthcoming. It is just having some knowledge to be able to ask the right questions in the time allotted. Thanks again.


Asking questions

by AgentX86 - 2019-09-15 13:50:11

There are two sorts of patients, those wo want to be completely involved in their situation and those who don't want anything to do with the details. By doing research and asking intelligent questions, your EP will put you in the first group and include you in on more of the decisions.

For your husband's sake, he wants to be that guy. AF is a royal PITA and he really has to take (keep) control of it. Only he can know how he feels and how to make the necessary tradeoffs.The more the two of you are involved in the treatment,  the more power his EP will give him.


Asking Questions

by Boneysjoint - 2019-09-15 16:27:12

 We are definitely in the “asking questions” group, and we have avidly been reading other people’s experiences and anything else we can find however there just seems so much to take in regarding Afib and pacemaker setting etc  and tomorrow we are just concerned that we may not be well enough informed to be able to agree or disagree with any answers given. Still I guess if that is the case then another appointment will be needed.

So0mething is amiss!!!!!

by donr - 2019-09-15 23:09:43

"Since the Ablation he has been in the main inNSR (he does get a lot of extra beats) with a few episodes of AFIB."  A quote from an earlier post you made.  John may have gottren the PM for "Complete heart block" but you did not say if he was totally dependant on the PM -or if he has periods when his heart functions in NSR.  You stated that he was in NSR  "in the main."  That tells me that he does have normal heart beats.  The PM only works when it has to in order to create a late or missing beat.

To really answer your question, we (& your EP) have to know how often his heart is in NSR.   A couple of comments:  1) IF the PM is functioning correctly, it will not vary in rate such that you can sense it.  The PM works in increments of time called "Milliseconds" - 1/1000 of a second.  It uses a digitasl clock that is extremely accurate, so you would not see variation on the Pulse/ox.   This tells me that there is a posibility the PM is faulty - FAT CHANCE of that.  PM's are extremely reliable & I have not heard of one failing - at least not the electronics part.  The leaast reliable part of the who;e system is the pair of leads.  ou might ask your EP if there is a chance of a lead failure - perhaps intermittent - that will allow such a situation as you are seeing.  2)  Yes, there is something wrong - this is not all in his head.  3)  The Pulse/ox is a terrible device for determining NSR.  It calculkates the heart rate for EVERY beat & as Crysty said, there are many reasons why & how it can give you such widely varying readins on a beat-for-beat situation.    It measures the time between beats & converts it into a heart rate for every beat.  If those were successive beats, John's heart rate does indeed vary wildly.  That is not an NSR at all.  All you can truly say is that his heart doesn't skip beats.   4)  It is posssible that he is having strings of PVC's (Premature Ventricular Contractions) where there is no P wave at all.   They could occur at irregular rates & the  PM would & could not react to them.  It would not send a contraction signal to the ventricals in that case.  The Pulse/Ox would, perhaps , record them as beats, but since they can have a flakey shape & strength, it would not give you a decent HR measurement.    5)  You did not mention if John has an existing "Escape Rhythm," a separately existing AV node rhythm that tales over in the event that the  that there is a long period block in signals to the node.  It is typically much lower - like 35-40 BPM - so it cannot interfere w/ the normal functioning of the heart.  Some people who are 100% dependant on their PM may have a comple lack of normal ventricular node function, but they continue to have an escape rhythm.  

You are on the right track - educating yourselves so you can get answers to your questions.  Wish you luck during ther audience you have w/ your EP.


Good appointment with EP

by Boneysjoint - 2019-09-16 18:04:01

My Husband and myself had a very positive appointment with the EP today.  Really felt listened to and understood. It appears John’s heartblock has progressed. Originally pacing at 14% now his Ventricle pacing is 80%. He has only had Afib 3% of the time.  John has got to have an echocardiogra m as the EP said the change in the amount of pacing can affect the heart and sometimes the lower chambers can beat out of time with each other and cause the symptoms that John is suffering from. If that is the case then a third lead in his pacemaker will help. If the echo is fine the EP will explore other avenues.


Thanks for the follow up report

by crustyg - 2019-09-17 11:14:11

So glad to hear that the consultation went well.  For so many of us, just feeling respected and listened to is a key part of building trust - and apart from surgical heroics, the healing and care process depends on trust.

Having the heart contract when driven by the PM as it would in normal health seems to be very important.  While there's an obvious benefit to maximising heart output per beat by having atria contract, then at the correct time later having the ventricles contract, it's clear that for some patients even the sync between right and left ventricular stimulation matters - hence the possibility of a third lead.  Please don't flame me for not mentioning His-bundle pacing...

Not mentioning His-bundle pacing

by Boneysjoint - 2019-09-17 15:20:45

i have not heard of His-bundle pacing, I will have to investigate. 

It *might* have saved a third lead

by crustyg - 2019-09-18 12:31:04

It's becoming clear that pacing the right ventricle causes remodelling of the left ventricle and this can really matter.  For some folk the answer is to add a third lead (which I *think* is placed by the coronary sinus as this provides a convenient area that provides good electrical conduction from there to left side of the heart).

His-bundle pacing isn't new but it's become much more popular since the realisation that RV pacing can be detrimental: the 'beauty' is that it introduces the pacing stimulation into the normal conduction tissue that shares the impulse between right and left ventricle as it would normally appear if the AV node were working.  It's supposed to be more tricky to get the placement correct, but with the modern EP mapping tools available, and some practice some EP docs claim that it's no more difficult than any other lead placement.  And you have only 2 leads.

I've only paced one patient with a temporary pacing wire - a *very* long time ago, and I have a *lot* of respect for EP docs who can wiggle leads into tiny little openings and quickly!

His-bundle pacing

by Boneysjoint - 2019-09-18 19:59:12

I have been reading up on this, interesting. If the results of my Husbands echocardiogram shows the need for a third lead I will ask the EP about His-bundle pacing.  Thank you for the info, much appreciated.

Results of Echcardiogram

by Boneysjoint - 2019-10-04 20:23:31

Just an update on my Husband, he had the Echocardiogram and had an appointment today with the EP for the results. His EF has dropped since April from 55 to 40. So a third lead is being put in next Thursday along with a change to the 'generator' in the pacemaker. The EP mentioned desyncrony between the ventricles (not sure if I have the correct spelling). Fingers crossed this will help the breathlessness which has become a lot worse over and affecting his quality of life over the last few months. Thank you all for your previous replies.

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