downsides to long delay pacing


Are there any physiological problems (other than the palpatation feeling) of such a long delay before the ventricles are paced? 

My pacing interval is 1.5 seconds (VVI40). So when I am in AV block a whole 1.5 seconds occurs and then my ventricle is paced. When I am sat down working or falling asleep this feels like a palpation or thud.

I am fine with managing this feeling moving forward as I know it is the long pacing interval but intuitively it does not seem right to wait for so long before pacing.

Without going into too mcuh detail - if the settings are changed to DDD or AAI-DDD I am paced 100% of the time.


Just a few thoughts

by Gemita - 2023-09-15 06:02:44

John, a 1.5 second pause is not significant and some may not even feel it, but clearly you are experiencing symptoms - thumps.  Have you recently had a pacemaker check or wore a holter monitor to see what is happening over a period of 24 hours or longer?  That might help.  Maybe you are getting ectopic beats as well?

I pace AAI<=>DDD but I do not have any significant heart block.  I am not confident AAI mode can be used for you because of your heart block.  Perhaps DDD mode rather than your current VVI mode would suit you better and then have them make suitable adjustments until you feel more comfortable and pace the right amount in your right ventricle (RV) since I know you have always been concerned about the % time you are being paced in your RV.  I know you have been struggling with your current pacing mode and low heart rate setting.  Have there been any improvements or any changes to your settings?

Are there any physiological problems from the delay, you ask.  Only time will tell, but if you are feeling uncomfortable and feeling symptoms with every beat, I would suggest that you could very well trigger worsening symptoms down the road.  For example when I have pausing from ectopic beats which are of equal length and they go on and on, I quickly develop tachy symptoms, deteriorating into AF (atrial fibrillation).  Long pauses (more than 3 seconds) would be more concerning, but your 1.5 second pauses wouldn’t be felt perhaps if you switched to another mode or increased your lower heart rate limit from its current low 40 bpm setting?  

Was wondering more about studies

by quikjraw - 2023-09-15 07:15:13

Hi Gemita,

Hope you are well.

The pause is not causing the sensation it is the beat after the pause that is causing it. I know this for certain because the two are concurrent when I feel my pulse. 

Unlikle most people in AV block fitted with a pacemaker I actual can perceive my blocked beats when I am at rest as the pause is 60/40 seconds = 1.5 seconds which I can feel in my pulse and then when I feel the paced beat it gives me the unpleasant sensation at that very point.

I am presuming what happens is that due to the longer delay on blocked beats my ventricles continue filling with blood and the resulting contraction is stronger to pump more blood out of them. It is this what is causing the sensation I think.

My concern was if this was something that could damage the heart or reduce the blood flow? 

If there is a negative (other than the feeling) then I can weight this up against going to 100% pacing?

They have said that they cannot move to say VVI50 as this causes issues with paced beats occuring at closer to intrinsic beats.

seems long

by Tracey_E - 2023-09-15 09:10:10

Seems like a very long delay to me. It's long enough for multiple atrial beats. The ventricles are holding that blood extra long which means they stay stretched. I don't know if it does damage long term or not but it seems to me that it isn't good. Hopefully someone who knows some facts will chime in, that's just conjecture on my part.

I get wanting to eliminate unnecessary pacing and giving the heart a chance to do it on its own, but the whole point of pacing heart block is to keep the ventricles in sync with the atria. That's not unnecessary pacing, it's just the pacer doing its job. 

Is there a reason it's set that way?

me too!

by quikjraw - 2023-09-15 10:33:27

The EPs I deal with seem to conclude that I only have two options with my long PR interval (nearly 500ms apparantly) I either go for bare minimum pacing (VVI40) or 100% pacing DDD or AAI-DDD.

I have run out of knowledge and time to be able to know if that is really true so I am left with no option but to try and change hospital for a second opinion.

I run like you Tracey but my ability to perform is now restricted i am about 20% slower for exactly the same effort as before the pacemaker. I expected this when I first had it fitted but I am nearly 3 years in and I can barely drop my times even though I am putting in the training. I also think it is making me tired all of the time. 

Try something different

by Gemita - 2023-09-15 10:51:11

Who has created the long PR interval John?  Have you or your doctors created this by chance by worrying too much about reducing the amount of RV pacing I wonder?  Wouldn’t it be worth trying DDD mode (again) and playing a bit with your lower rate limit setting first.  You might need far more pacing support than you are currently getting.  What have you got to lose by trying?

Changing doctors may not necessarily help if you want to continue doing the same thing.

try it the other way

by Tracey_E - 2023-09-15 10:56:49

I'd want to try it the other way if it was me. 100% pacing with heart block is the norm. See how you feel. Sounds like now you aren't pacing as much, but you also aren't feeling too well?

Does your doctor work with many athletes? if you find someone else, you might start with that.

Sound advice

by quikjraw - 2023-09-15 11:49:41


I may have confused you. The PR interval is my own heart's time period between atrial contraction and my ventricles starting to contract.

I am set at VVI40 which ignores the atria and simply ensures there ventricules contract at no less than 40bpm.

I think you are right it is definitely worth looking again at DDD.


I think that is a fair summary, I am not totally miserable and feel lucky to be able to exercise again. Maybe if I do move to the other hospital I will ask if they have EPs who work with people who still want to exercise to a higher level.


by Penguin - 2023-09-15 12:28:43

I have to say that I would find it similarly difficult to make a decision, but I have found VP detrimental and had some very unpleasant (and frightening) symptoms. 

You don't say whether you stopped the 100% VP because you felt unwell or for some other reason - worrying echo or blood test results perhaps or perhaps because it felt sensible to reduce VP at the time?  These are all valid reasons and if they're in the mix, your doctors really need to explain them to you so that you can be aware of the risks vs benefits of continued high VP and create a plan that sits comfortably with you. 

Neither approach is to be shamed. The decision making is a balancing act - how much VP feels OK and how much makes you feel unwell - if at all? Is there a way to keep it at bay without compromising heart health? Is there a plan if you accept 100% VP and become unwell?

These are important topics to discuss with your doctor. I hope you find an acceptable way forward if this VVI 40 bpm setting is not working for you. 


Could you ask for an upgrade of your system I wonder?

by Gemita - 2023-09-15 14:49:26

John, you sound as though you are experiencing ectopic beat after ectopic beat from your description of pauses, followed by a thump with every paced beat and this is likely caused by your pacing mode/low base rate.  As an ectopic beat sufferer, pausing, thumping heart beats can certainly affect blood flow if they are frequent/prolonged.  I would suggest that your pacing induced symptoms, if allowed to continue, could lead to structural changes like cardiomyopathy.

Did you experience any symptoms with DDD mode apart from a high pacing % in the right ventricle?  I think you had some tachycardia runs at one time too, if I recall correctly.  

How does your present VVI mode at 40 bpm compare with your earlier DDD mode/base rate at the time?  Do you feel worse today, or better?  And what about your general health/autoimmune condition;  is this stable or are you still on powerful meds?  Lots of questions but they might all need answering to help you to come to the best decision.

You sound like me, very sensitive to ventricular pacing but "barely" pacing is clearly not working.  I would try DDD mode again and if you start getting signs of dyssynchrony from RV pacing, you could perhaps ask about an upgrade to your pacing system either now or in the future, to see if that would help to make you feel more comfortable


by Penguin - 2023-09-16 05:06:30

'' I would suggest that your pacing induced symptoms, if allowed to continue, could lead to structural changes like cardiomyopathy.''

That's quite a suggestion from a layperson Gemita!  Surely a reputable EP wouldn't suggest a VVI 40 bpm setting and leave Quikjraw on this setting without discussing something as serious as cardiomyopathy as a potential risk? 


by Gemita - 2023-09-16 05:57:54

I am happy to leave my comments up, despite your intervention.  If John wishes I am happy to give personal details by private message to support my "suggestion".  I was not suggesting that a reputable EP would leave John with a dangerous setting, those were your very words Penguin, not mine.

Don't worry

by quikjraw - 2023-09-16 06:49:14

Do not worry I had not thought about cardiomyopathy being a potential risk if long pauses are happening at a high rate but it is certainly worth be asking. I will also look for studies but I expect that long pauses for hundreds of beats is something they did not look into as they would general want that to be treated?

I cannot imagine VVI40 was intended for people with 2:1 heart block so I need them to at least consider this point. I also thought that at a basic level i'm simply not getting a decent blood flow  during constant 2:1 block episodes. 

The only issue I remember when paced at 100% was that initially I think they had my minimum pacing level at 60bpm. When they moved that to 50 everything seemed good. Unfortunately I was not able to know how well that would work for exercising becuase at roughly the same time I had a total rebound of my auto-immune joint issue. If I remember I only just managed to do the treadmill stress test. 

However, now for reasons that are not clear I am in total remission with both my joints and my Crohn's. I do not need any immunosuppressants. My only limiting factor in exercise seems to be the settings on my pacemaker. Lot's of friends and family have said that I am slower because I am older and I should just not worry about it .This is frustrating to hear because I know that is not true. I simply do not have enough heart beats to meet the demand my legs are pushing.

Gemita, Tracey and Penguin you have given me clarity in what I do next and the questions to ask. 

I think my plan will be to ask for a new treadmill test but see if they have any options to only increase pacing demand 1:1 above say 100 or 120. If that is not possible due to my long PR I will go back to 100% pacing. The problem is that there is never a cardiolgist and EP in the same appointment they seem to stay separate.

I think after that I will transfer to Liverpool Heart and Chest hospital as the long term goal will be for me to have better lead placement and I suspect looking at the statistics they are much more liekly to achieve that for me.

Thank you John!

by Gemita - 2023-09-16 08:03:51

I think you have a lot of questions to ask your present team in view of your symptoms and I think it is an excellent idea to consult the Liverpool Heart and Chest hospital if you continue to make little or no progress with your current team.  

I know you got your Medtronic pacemaker at roughly the same time as my husband and I received our Medtronic implants in 2018.  Hubby is also paced VVI (at 50 bpm) for intermittent heart block + bradycardia + slow Atrial Fibrillation, although of course he is much older. 

I am delighted to hear that your autoimmune conditions are in remission and that you don’t need immunosuppressants.  Perhaps now you have the chance to fully test your pacemaker in DDD mode, without powerful medication affecting your ability to exercise.

Please keep posting John.  Your journey has been an interesting one and I want to see how it "successfully" continues

Perhaps a shorter delay?

by PacedNRunning - 2023-09-18 18:24:55

I had intermittent block at implant. I had long AV delays. I was also sensitive to pacing according to them so they set my PM with long AV delays.  I didn't feel well.  I came in once a week for 4 weeks for them to shorten my AV delay until it felt tolerable. When my block got worse, I could feel that delay with a continuos thump in my heart.  Very similar to ectopic beats but instead of randonmly they were continuous.  Shortening the delays helped.  You may not necessarily pace 100% if they change AAI to DDD, I think that's what you said. It will be based on timing cycles. So if your own heart can beat before the timer runs out, the pacemaker will withhold pacing.  So you may not pace 100%.  I paced about 50% until about 18 mos post op and my pacing slowly increased to 100% with the same settings.  That's how we knew my block got worse. Hopefully you are feeling better by now. 


by quikjraw - 2023-09-19 06:00:57

Excellent news, I have an appointment with the pacing team next week! 

Gemita I will certainly update my progress after that appointment. I will probably raise another post.

PacedNRunning you sound almost the same as me!

I will get the opportunity to ask if the AV delay can be lengthened at the lower heart rates to the maximum delay and then ramp up during exercise. My PR interval is approaching 500ms (not sure how often) so I think they have little or no room for adjustment. 

In the long-term it would be good if they can consider moving my lead to HIS bundle pacing then 100% pacing is something I can forget about.

If they do change the settings next week I will post how the runs are feeling with being more supported.

Keeping my fingers crossed

by Gemita - 2023-09-19 06:43:14

Now don't forget to worry less about "lengthening" everything and focus more on getting relief for those symptoms, however they achieve it?  Hope the appointment is not rushed and you are able to cover your main concerns.  I look forward to the update

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