Risks of long-term RV pacing - episode 2

In my earlier post "Risks of Long-term RV Pacing", I was enquiring about the risks of long-term RV pacing for someone like myself who has total heart block, but a functioning sinus.

As the discussion developed, several contributors with SSS joined the discussion to add their own, very welcome, Qs & As. This leads me to ask whether there is any difference in the risk level for heart failure between the two groups. I.e., does it change anything that the signal to pace my RV is essentially a delayed pulse derived from the one that just fired my RA, compared with those with SSS where the pacing pulse comes directly from a PM algorithm?

I am completely ignorant here, so you can safely assume I cannot suck eggs! I just do not know  whether RV pacing in the SSS case produces the same sort of synchrony between atrium and ventricle, and possibly between ventricles, that I imagine could occur in my case - or whether that would even make a difference. Could someone please explain what happens in both cases. Many thanks.


RV pacing for me as a sick sinus syndrome patient clearly triggers symptoms

by Gemita - 2023-09-11 19:22:37

Repero, you were originally concerned about a high burden of right ventricular (RV) pacing potentially causing pacing induced cardiomyopathy or dyssynchronised pacing, ultimately leading to heart failure symptoms.  You are now wondering whether there is any difference in the risk level for heart failure between heart block and sick sinus syndrome (SSS) members?  Some members have both SSS and heart block or develop both at some stage.  Both SSS members and heart block members could be equally at risk of potentially developing heart failure from a heavy burden of RV pacing.  As we have already discussed, the majority of members never go on to develop problems and those that do, will likely be treated with a pacemaker upgrade (Cardiac Resynchronisation Therapy).

As you will always read here, the total % of pacing required in either the right atrium (RA) or RV will depend on so many factors that could affect this, like medication which could slow conduction from the atria through the AV Node or even be the cause for an intermittent heart block.  The amount we need to be paced in either chamber could also be caused by a worsening of our electrical disturbances from an arrhythmia or progression of our heart block because of another untreated health condition (inflammation or an infection for example), or even by lifestyle changes, so you can appreciate how many things could affect the % time we need to be paced in the RV or RA.  (And let us not forget changes to our settings could affect our pacing percentages too).

As an example, when I got my pacemaker, I needed pacing in both my upper and lower chambers to a high degree because I developed worsening rhythm disturbances whilst my heart was settling down and getting used to being paced.  This required powerful medication at high doses which slowed conduction through the AV Node, causing left and right bundle branch blocks.  With settings adjustments and treatment for my arrhythmias, after 3 months I was pacing at 100% in my RA with only about 1-2 % pacing in the RV and this has mostly continued since 2018.  Of course my risk is minimal at the moment for heart failure from RV pacing but this situation could change at any time should my rhythm disturbances increase and trigger automatic mode switches.  I would then find myself pacing in the RV and only returning to RA pacing when my arrhythmias stopped.

Clearly in the context of your question, a member with heart block is more likely to need pacing in the RV than a SSS member without heart block, potentially increasing the member's risk for heart failure, but this may not always be the case.  I am always symptomatic during RV pacing because of the loss of atrioventricular synchrony as well as a loss of synchrony between both my ventricles.  Of course like some fortunate heart block patients, a SSS patient may also be completely asymptomatic with RV pacing which is why we still need checks throughout our lifetime to ensure that all remains well.

Great question!

by PacedNRunning - 2023-09-11 20:41:30


PICM comes from the way the ventricles contract when paced.In  Normal conduction, the ventricle signal comes from the SA node to the AV node (PM) to the HIS bundle down to the Purkinje fibers to your ventricles causing them to contract together. With the PM, the signal is from right (RV lead) to left and down the ventricles.  It's that slight delay from right to left that can lead to PICM, not from the timing from atrium down to the ventricles. Instead of the ventricles beating together with normal conduction, there is a slight delay of milliseconds. This is similar to RBBB/LBBB (right/left bundle branch block). People with RBBB and LBBB don't always end up with heart failure.  LBBB are more likely to end up with low EF but pacing CRT-3lead will help their heart coordinate.  This is where lead position is important for the RV lead.  Original placement is apex of the ventricle ( lower base of the ventricle, further from the HIS bundle), septal placememnt is higher up in the septum closer to the HIS bundle.  This is why the HIS bundle placement and Left bundle branch area pacing (LBBAP) are considered conduction system pacing because it's the same as the normal conduction pathway.  When they place a 3rd lead, they are pacing both sides together because each lead is activating each side of the heart just like normal conduction.  


With SSS, the reason they can develop PICM is not because of the signal from the SA node to the AV node, but the fact the pacing the RV unnecessary because they do not have AV block. It's causing dyssynchony in the ventricles of the heart that can beat on it's own. In fact, doctors don't mind pacing the Atrium as much as they want. The DAVID study revealed the PICM developing in those with SSS and no AV block. The study participants were also older with low normal EF's.  I wish they would repeat this study because I've seen other's paced 20+ years without developing PICM. I've researched this quite a bit my first 2 years of pacing. I have several articles printed out about this. The most recent and I will see if I can find it, found those with normal EF prior to implantation and younger, did not develop PICM in the first 10 years of pacing.  It was a very low risk.  There are studies showing that pacing can lead to afib. I haven't dove into this one as much because I couldn't find enough articles to explain it. When I asked my EP, he agrees it can but never gave a percentage.  Only article that gave me a little insight into PM causing afib was that it was detected with PM recipents because we have PM's to record afib and early identification vs someone without a PM. Those with and without PM's can go years without knowing they have afib.  We luckily have these devices that will detect afib.

I hope this helps. Please verify things I said with your team. 

Moving up the learning curve!

by Repero - 2023-09-12 05:08:04

Many thanks to Gemita and to PacedNRunning for these very helpful responses.

I was particularly interested in PacedNRunning's explanation of how PICM arises due to the delay between RV and LV ventricles. I am suddenly wondering whether my previous long history (which I failed to mention) of RBBB comes into any of this. The RBBB was fully investigated and never caused me any problems.

To further muddy the waters, I have just re-read my surgeon's discharge letter. He states that the RV lead was placed "low septum/apex" - does this mean anything, or was he just not sure where it ended up?

If you feel that we should be discussing this via PMs, please do let me know.

You are a good student!

by Gemita - 2023-09-12 08:38:32

Repero, personally I find your questions and all members’ answers of immense interest, so why should you deprive yourself and us of a valuable source of discussion?  Please continue to post your questions openly.  I see no need to discuss this via private messages, although you may wish to do so if this is your preferred method of communication?

The site of my RV lead tip placement is stated as:  RV Septal area.  I was told that midseptal ventricular lead placement is superior to the apical location.  

From your description Repero of "low septum/apex" I am unclear if you have mainly septal or apical pacing.  Your description would appear to be RV apical pacing.  However since you feel well with no symptoms, I do not see a problem, at least not at the moment, but may need watching.

You might like to have a look at the following links and then discuss any concerns you have with your doctors, particularly regarding any bundle branch block activitiy.  I still get this problem intermittently (LBBB and RBBB) but it no longer causes troublesome symptoms with my pacemaker.  It sounds as though you were never symptomatic even before your pacemaker so unless you start having new symptoms, I would still feel confident that all is well and will remain well with active follow up and good care




by Repero - 2023-09-12 09:51:15

What an amazing video link! The surgeons achieve the seemingly impossible. Working at the end of a long floppy wire, to be able to place it so precisely is beyond impressive. To me, the difficulty is compounded by the fact that the heart itself is not visible in the radiography images - or am I missing something? I must read more about this.

In my own case, I have only one other incidental clue to the RV lead placing. At my first review they checked the electrical energy required from the pacing lead to initiate a reliable ventricular contraction; this is routinely checked and optimised by the PM in a daily trial and error routine. The aim is to use the lowest voltage and shortest duration pulse to achieve the result. Mine was very low and both physiologists seemed impressed. They said it was good for battery life and indicated "good lead placement".

I would be very interested in any comments on this aspect.

It is looking good so far

by Gemita - 2023-09-12 13:33:41


Hello Repero, when we were discussing this subject in the past, a helpful member posted a Conduction System Pacing Diagram showing the various areas of pacing.  You might like to download a copy from the above link, to keep on your desktop that you can refer to.  It shows the major Conduction System pacing areas. 

I believe they use fluoroscopy at the first sign of resistance as they advance the RV lead. The end goal is to place the lead at the inter-ventricular septum, mid point to ensure a paced QRS complex as narrow as possible by delivering the impulse near simultaneously to the right and left ventricle.

As for your placement, my own view is that it has been a successful RV lead implant since you are completely symptom free with your current lead position/settings.  A long potential battery life will be a bonus too.  Now we have to hope that there will be no adverse RV pacing difficulties in the future, but it all sounds extremely promising.

Another great link!

by Repero - 2023-09-12 14:24:33

Thanks Gemita, very useful.

It is also good that my natural pessimistic tendencies are being more than offset by your buoyant optimism!

Lead placement

by PacedNRunning - 2023-09-13 19:38:11

HI Repero, I interpret your doctors note of low Septum/apex to mean you placed it near the apex of the heart but on the septal wall. They can place the lead direclty into the apex or on the septal wall.  My EP originally explained the high septal lead placement was superior over apex but new research has shown not much difference in the 2 areas.  He said he went back to placing them on the apex.  I have a high septal lead placement. I have to ask, have you had a 12 lead EKG post implant?  Studies have shown a QRS duration >150ms can lead to PICM. The higher the duration, the higher the chance of PICM.  Mine is 152ms at the septal well.  At this point, I've learned getting regular yearly echo's is the best way to diagnose PICM earlier rather than later. Some can have no symptoms at all and develop PICM. Our bodies are well built machines and can compensate for a low EF.  

I don't think RBBB causes issues. It's typically benign. 


Role of Pacing Mode in the Development of AF

by Penguin - 2023-09-14 06:43:15

'There are studies showing that pacing can lead to afib. I haven't dove into this one as much because I couldn't find enough articles to explain it. When I asked my EP, he agrees it can but never gave a percentage'  

- PacedNRunning

This article by the same author as the previous article that I posted (Dr Israel) is an earlier paper (2006) and refers to studies looking into AF and pacing mode from the 1990s-early 200's.  It refers to the DDD(R) setting and it's propensity to cause unnecessary VP. 

It also discusses pacing site and (being an earlier paper) it replicates some of the comments about the septum as a pacing site which we've already discussed.

It seems to link AF to unnecessary VP in DDD(R) pacing and discusses AV delay programming - nominal and long.  (Nominal = the AV delays that come as a factory setting)   Comments are also made re: longer AVD programming. 

Useful perhaps? 


Role of Pacing Mode in the Development of AF

by Gemita - 2023-09-14 14:02:34

Yes it would be perfectly feasible for atrial fibrillation (AF) to be triggered by a poorly adjusted pacemaker, set in the wrong pacing mode.  Clearly I say this with a degree of confidence because my AAI pacing mode has “effectively” treated many of my atrial rhythm disturbances, that I am hardly pacing in the RV at all. 

For someone who was heading for an AV Node ablation before pacemaker implant, when anti arrhythmic and beta blocker meds, cardioversions and other treatments failed, I think my experience has been rather telling of the importance of getting the correct treatment for any arrhythmia, particularly one like AF.  The correct pacing mode (AAI) and other settings are certainly working well for me.  

I am pleased I waited and gave myself time to assess the benefits of pacing before rushing into other treatments like an ablation.  I know it was the right decision for me because I am experiencing fewer symptoms overall, confirming that I am remaining in normal sinus rhythm most of the time.

I would suggest the wrong pacing mode could also trigger the development of other arrhythmias too, not just AF.  

The problem with AF though is that sometimes no trigger can ever be found;  there are really so many potential triggers for the development of  AF which is why it can be so very difficult to treat.  AF can be triggered by stress, bereavement, alcohol, exercise, infection, an inflammatory illness, sleep apnea, high blood pressure, a falling ejection fraction, heart failure, coronary artery disease, lung disease, medication, gastric reflux and ageing itself which none of us can prevent, and I could go on, so with so many possible triggers, it is often impossible to pinpoint the exact cause of worsening AF episodes since there may be several triggers occurring at the same time.

For example I developed AF before my pacemaker, so AF was certainly not triggered by pacing.  My husband also developed AF before his pacemaker.  He paces with a single lead to the RV, which has certainly not helped to stabilise his AF but the pacemaker hasn’t worsened his symptoms overall, quite the opposite.  It has been immensely beneficial to treat his bradycardia and heart block.

Fortunately Repero doesn’t have AF and has a heart that is completely at peace now and I hope it stays that way.

Atrial and Pulmonary Vein Stretch link below might be worth a read for AF sufferers:



Reply to PacedNRunning

by Repero - 2023-09-14 16:25:57

I have not had, a 12-lead ECG since implantation. I do, however, have a Polar H10 chest-strap heart rate monitor. I paired this up with a phone app which purports to analyse the ECG trace from the sensor. This reported a mean QRS width of about 170 mS.

However, looking at the form of the trace it "analysed" I am at a loss to see how it found any QRS width to measure. I intend to ignore this on the grounds that, 1. it is only a phone app, and 2. I can't do anything about it now anyway.

I think I'll go with Gemita's, "If you feel all right, you are all right!" approach.

Thanks for the info though, it's just the sort of thing I like! Numbers to worry about!

Unnecessary VP

by Penguin - 2023-09-15 06:22:50

Gemita / Repero, 

The link was in answer to PacedNRunning's comment about studies into VP and A.Fib.  Thank you also for your link Gemita. I will read it.

Gemita, I agree with all that you say about alternative causes for AF - you're quite right. AF may have other causes and it wouldn't be sensible to 'assume' that pacing is the cause.

 A.Fib induced by a pacemaker that has not been programmed correctly is something that we, as laypeople, cannot easily guard against.  We all have to trust, particularly when we are new to pacing. Not many of us know the ideal length of AV delay for our heart when programmed to DDD(R). Unfortunately, it can be difficult to understand all of this, let alone challenge our settings if necessary.  

Gemita - PacedNRunning suggested that your mantra of symptoms, symptoms, symptoms isn't always helpful. I agree with this to some extent.  However, personally I would have found it incredibly useful to know which symptoms to look out for because I had lots of them and some of them crossed over with other causes.  I had no idea that pacing could cause any problems at all and I think it would be helpful to flag some of them up.

Please let me know whether or not you feel that this would be pertinent to this thread or not. 

Repero, I agree that to a certain extent 'going by how you feel' is entirely appropriate most of the time.  However, IMO 4 checks - i) symptoms  ii) pacing report iii) blood tests and iv) regular echos will safeguard you the best.  

I also agree that it is unnecessary VP that needs to be watched alongside the amount of VP.  Those of us paced via the DDD(R) mode need to pay the most attention,



Penguin, PacedNRunning and Repero

by Gemita - 2023-09-15 07:52:41

Penguin this post has to some extent gone off topic from Repero’s initial question and it might be better if we start another thread because PacedNRunning’s comments about studies into VP and AF are important and we might all benefit from her question being posted in a new thread or from any further comments/recommendations you may have too? 

I don’t recall PacedNRunning saying specifically that to go on symptoms symptoms symptoms isn’t always helpful.  I recall she agreed with my comments in an earlier thread from Repero by saying “No symptoms and everything is good. Our body has symptoms to warn us if something is out of balance. Our body works very hard to keep us balanced. So when something is off, we will know”.  She further stated:  “one thing with PICM is it can come up with no symptoms. The RV pacing can cause the LV to enlarge over time. Regular echos can pick it up early . . .”  I think we are all agreed about her latter comments and I have always suggested that Repero is closely watched since he is pacemaker dependent.

Repero, while I agree with Penguin about the importance of regular checks, you may find your doctors unwilling in the current climate to do regular echocardiograms or blood tests in the absence of symptoms?  In my experience, echocardiograms are certainly not routinely carried out in the UK unless there is an indication to do so, like a new symptom:  breathlessness, chest pain.  My husband with right sided heart failure, for example, doesn't routinely get an annual echocardiogram.  A pacemaker isn’t always an indication for say an annual echocardiogram or regular blood checks, although pacemaker dependency might get you on the annual waiting list for an echocardiogram, so I would respectfully ask your doctors how they will manage your care in the future?


by Penguin - 2023-09-15 08:29:05

Yes, I completely agree. 

Re: PacedNRunning's comment about symptoms - She said that symptoms are not always detectable when high VP is causing a problem and your suggestion is to go by how you feel. I straddle the fence on that one because, in my experience some symptoms provided a very clear indication that there were problems, whilst others only showed up in blood tests / echos and some were intermittent and difficult to reproduce.  

I also agree about the NHS and regular checks. There may be exclusion / inclusion criteria.

Repero EKG

by PacedNRunning - 2023-09-15 19:12:25

I wouldn't use the QRS duration from at home devices.  I would use a medical grade EKG. I always ask for a 12 lead EKG once a year. My EP doesn't mind doing one.  My 12 lead EKG is 152ms-153ms but my apple watch apps Qaly interprets them at 170-200ms.  These devices don't read very accurate so I wouldn't even consider that number as accurate. :). Bottom lline that I've learned after all my research is, get yearly echo's.  Just remember, there is a fix called CRT 3 lead. Also remember many are paced 100% many years and do fine with a normal EF.  I hope we've helped understand your risks and how to be proactive in your care. 


Reply to PacedNRunning - EKG

by Repero - 2023-09-16 04:54:30

Thank you for that clear recommendation PacedNRunning. Everyone has indeed been very helpful.

A yearly echo is obviously desirable but, as other UK residents have observed on this thread, may not necessarily be available without symptoms to prove the need! Same goes for an EKG.

Meanwhile, and just because I am interested, I have been trying to learn how QRS width could ever be measured from an RV paced heart trace - it just looks entirely different from normal, without any of he features which would normally define its start and finish. I have an EKG rhythm trace and could estimate QRS width manually, if I just knew what to do!

Thanks again for your help.


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I just want to share about the quality of life after my pacemaker, and hopefully increase awareness that lifestyles do not have to be drastically modified just because we are pacemaker recipients.