Algorithms to Reduce Ventricular Pacing

Pacemaker Algorithms

by Gemita - 2023-11-23 13:54:49

Penguin, 

Your 2nd link was another great find.  It is good to compare manufacturer differences on algorithms.  

Yes everything in life has risks and benefits and our pacemaker algorithms are no different, are they.  Because our heart condition never stays the same, what is set up in our devices becomes even more important.  With our electrical disturbances frequently changing, we need to make sure that the algorithms that have been set for us have the ability to adjust to our changing “internal” environment. There is absolutely no point in trying to avoid pacing in the RV at any cost, if this causes harm or creates worsening symptoms.

I was interested to read about the recording of mode switch arrhythmia episodes and to see that Boston Scientific and Sorin devices store a larger number of episodes on EGMs, more so than Medtronic or Biotronik, although symptomatic significant events are usually stored on my Medtronic device since these are frequently found and discussed with me.

I see an unexpected advantage of recording a larger number of mode switch episodes provided by Boston Scientific (RYTHMIQ) and Sorin (AAI SafeR) is the opportunity to review EGMs which could lead to early diagnosis of pacemaker dysfunction (atrial or ventricular undersensing, loss of atrial capture, oversensing, or presence of noise) even when the problem is infrequent and intermittent.  These observations can trigger a change in programming (adjusting sensitivity or pacing threshold) or if lead dysfunction is suspected, provide an early alarm for the physician to investigate the issue further.

Arrhythmia induction.  As far as I can see my managed ventricular pacing (MVP) algorithm which is turned on to minimise RV pacing, allows me to miss a beat before the pacemaker will pace, but this is often a trigger for some of my arrhythmias, including AF.  All I want is to overdrive pace, not to pause.  My rhythm disturbances would be even worse if my base rate were lower, rather than set at 70 bpm, since this would result in further long-short sequences before being paced, which usually trigger rhythm disturbances.  I tried to ask to have MVP turned off, but my EP wouldn’t have it.   The risk of triggering an arrhythmia is also increased when other conditions are present, for example with electrolyte disorders, certain meds that can affect Capture Threshold.  I see this has led to the updating of the MVP algorithm to limit the duration of the pause in case of intermittent conduction delays, so I completely understand what you mean about the risk and benefits of some of our algorithms.  We cannot take our eyes off them and this is why when we start getting symptoms, we need better follow up and a resolution.

In closing, I am mindful that my husband has a simple single lead Medtronic pacemaker to his RV.  Despite all the fears about RV pacing, his Ejection Fraction in over 5 years of pacing has not changed.  He started pacing 40% of the time in the RV in 2018 and is now pacing over 80%+ of the time (although going for another check up early December).  With his simple pacemaker there is certainly less to go wrong and his battery will certainly last a good deal longer than mine.

Gemita

by Penguin - 2023-11-23 15:39:19

Thanks for your thoughts.

I was thinking of you when I read the Medtronic information and the info re: superior recording of events with Microport (previously Sorin) and Boston Scientific pacemakers.   It seems that BS may have a few features that would help you. Sorin (now Microport) used to make really good pacemakers - and I'm not saying that they don't anymore - but they seem to be increasingly uncommon in the UK. 

Sorin / Microport list / number all reasons for mode switch along with an ECG for analysis.  None of the other manufacturers list and evidence AVB episodes by type as far as I know.  

I hope the paper helps you assess these things prior to replacement. Point taken that reducing VP isn't necessarily an important issue for everyone, but it was to me and most EPs seem to take it very seriously.  As previously discussed 'unnecessary VP' is the one to watch in SSS (and LVEF - edit - as Selwyn says below). 

The first link is interesting in that it comments on long AVDs and diagnosed AV block.  The hysteresis algorithms apparently allow for more flexibility when there is intrinsic conduction rather than using a long, fixed AVD.  I understand the theory better now, but, as you know, PMT has been a significant issue for me.  

I'm pleased that the paper was interesting. 

Oh those Algorithms!

by Gemita - 2023-11-24 07:24:56

Penguin, I would be extremely happy if all the “reasons” for my annual, often over 2,000+ rapid in and out mode switch arrhythmia episodes were listed, recorded, stored for me to peruse.  I wonder how large the battery would need to be to accommodate this and to last for any decent length of time?    

Yes, like you, the more I learn about my Settings/algorithms, the better and this helps me to have that meaningful conversation with my EP.  I usually need to read several different research papers on the same subject to help with understanding and to clear the brain fog.  It isn’t easy, is it.  I will go back over your first link on AV delays/Hysteresis although my ?fixed? AV intervals are not long (Paced = 180 ms/Sensed = 150 ms) and I don’t have Hysteresis turned on apparently.  

I feel that a pacing pause from whatever Settings/algorithm source, is just bad news for me and a potential trigger for a rhythm disturbance.  However, I know that so many different Settings/algorithms are at play during pacing, none of them work in isolation, so programming can be tricky.

I do accept that a high percentage of pacing in the Right Ventricle can lead to worsening Atrial Fibrillation as well as to heart failure symptoms in some, if not many patients.  As I have mentioned elsewhere, I was told by my EP any signs or symptoms of dyssynchrony would likely happen quickly, if they were going to happen, say within the first few years of being paced.  If this didn’t happen, in my EP’s experience, it probably never would.  To an extent, I believe this since there are quite a few members here who have been pacing 100% in their Right Ventricle since childhood without any symptoms or signs of heart failure.  In fact many of these members lead extremely active lifestyles.  Nonetheless Right Ventricle pacing for some of us most definitely causes difficult symptoms.  I am clearly only comfortable being paced 100% in the Right Atrium.

Yes I suspect due to my active arrhythmias, my battery will need changing in the next year or two, so everything I learn in these pages will help me to get the best possible replacement.  I wonder whether my doctors are familliar with Boston Scientific or would consider giving me a different manufacturer pacemaker in the future with my Medtronic leads?  Worth asking about.

Be careful what you wish for.! Reducing right ventricular pacing.

by Selwyn - 2023-11-24 12:51:42

Despite the publication of a significant amount of evidence that has made us aware of the adverse pathophysiological mechanisms and clinical effects of prolonged Right Ventricular (RV)   pacing, as well as on the use of different strategies to overcome them, several questions remain unresolved. There is currently a lack of specifically designed studies that evaluate the potentially negative effect of long-term RV pacing in patients with normal left venticular function. 

No large scale trials have assessed the benefits and safety of the managed ventricular pacing algorithm in patients with high-grade heart block. This is not about battery life, rather remodelling of the right ventricle.

Can I refer you to a useful summary:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3857233/

If I may draw your attention to the various sub groups as to the benefit ( if any) analysis.

Mmmm...

Perhaps something to think about when considering upper rate limits?

I think hysteresis is fairly standard.  Personally, I had my atrial-ventricular blanking shortened to try to help me with exercise rate response.  Who knows?

Thanks Selwyn

by Penguin - 2023-11-24 14:57:01

'Who knows?' suggests that nobody does!

Not very comforting. 

More Physiologically-Correct Pacing Methods vs. High Ventricular Pacing Percentages

by DoingMyBest - 2023-11-26 20:55:44

I have a rather fundamental question with respect to minimizing ventricular pacing. For argument's sake, let's agree that right ventricular apical pacing (RVAP) is the condition most associated with potential cardiomyopathy (CM) and heart failure (HF). My question is with respect to other ventricular pacing sites. What do any of you know about Right-Ventricular Septal Pacing (RVSP), His Bundle Pacing (HBP), Left Bundle Branch Pacing (LBBP), selective or non-selective, and Left Bundle Branch Area Pacing (LBBAP) with respect to possible CM and HF, particularly with high ventricular pacing percentages? How do the more physiologically-correct pacing methods fare in the long-run with high pacing rates?

I ask because I am 100% LBB paced as an alternative to bi-ventricular CRT pacing. I've been thinking I should ask the technicians to enable an algorithm to reduce the ventricular pacing rate, perhaps wrongly assuming that the high pacing rate was a potential problem. Now I'm wondering if LBBP being more physiologically correct, there is not the problem I was worried about. Any thoughts on this?

Doingmybest

by PacedNRunning - 2023-11-26 21:35:35

You ask if you can minimize pacing? The answer would be no from my understanding of a Bi V pacemaker. It is soley placed to coordinate the ventricles contracing because your own heart is unable to do it.  If you minimize pacing, you are defeating the purpose of the Bi V pacing.  

RVSP has not shown a reduced risk in PICM.  It has not shown that it is superior to RVSP. I have RVSP. So far my EF has been normal.  

Algorithms

by PacedNRunning - 2023-11-26 21:50:22

I think most of us know the algorithm to minimize RV pacing was created because of the DAVID-MOST trial.  In this trial, it was found most did not need RV and were pacing unnecessarily.  The key is unnecessary pacing.  If you need pacing, you need pacing.  An example would be Gemita's AV delays 150ms sensed and 180ms paced. If they had programmed my PM with those delays at implant, I would have paced 100%.  They started my delays out longer and once the right delays were found, my own heart would beat the PM with delays 250ms or more.  Any less than 250ms the PM would beat me depending on the HR.  Which didn't allow my own heart to do the work. Sometimes the PM needs more time before intervening and most are not set to allow our own hearts to do the work.  The algorithms are nice but should only be used in those with no AV block or intermittent block.  If you have high grade block or persistent block, those algorithms should be off.  Rhythmiq was too bumpy for me with exercise.  I am now in CHB 100% paced on demand and my AV delays are now dynamic with max of 150ms sensed and 170ms paced. Any longer than 150ms I feel miserable and experience lower leg edema.  It's interesting how my delays changed becuase if I had them longer today, I would be absolutely miserable because the longer delays just equals to longer time my heart has to wait for a paced beat to help.  

I did a lot of research in this when I first got my PM. Also because my doctor was very concerned about unnecesary pacing. What I concluded after reading many research articles....is that the risk is very low. about 10%.  If your EF is in normal range prior to implant 55-70%, the chance of developing PICM is very low.  Even though 50 EF is normal and within range, 55-70% for PICM risk.  Physiologic pacing such as HIS and the newest LBBAP are similar to normal AV conduction and reduce the risk significantly.  LBBAP is easier to implant over the HIS. The HIS has smaller landing area and high chance of dislodgement. LBBAP has a larger landing area and I'm not sure of the rate of dislodgement.  

It would be nice if they could find a way to optimize our PM's with an echo. It can be done but it's time consuming and most doctors don't want to take the time to adjust to our specific hearts needs.  

My own EF was 65% prior to implant. 53%,51% and 63% this last year.  It was stressful and I did alot of research into this. Bottom line for me, is there is a fix called BIV pacing.  It's usually successful if low EF is caused by PICM.  I try and focus on that even though I never want 3 leads.  

PacedNRunning

by Penguin - 2023-11-27 07:12:08

Thank you for your post above.  

I've listened to my EPs re: pacing site (septal placement) and their opinions have varied.  Obviously, opinions change over time as results become apparent.

I've never asked about the pacing sites that you mention as they don't apply to me, but what you say sounds convincing.   

I hope that your own EF% continues to improve.

Appreciated, PacedNRunning

by DoingMyBest - 2023-11-27 11:10:59

Thank you for your insights. Very helpful.

I have read that remodeling of the conduction system can occur. This suggests that 100% pacing for ventricular dyssynchrony may be unnecessary for some patients if they have improved over time. I'd like to hear of a cardiologist that cares enough to check for this improvement and adjust accordingly.

DoingMy Best - Re-modelling

by Penguin - 2023-11-27 16:24:09

I have read about re-modelling too, but as a term that I didn't understand very well. What does 're-modelling' mean and how dooes it happen? Can it be negative as well as positive? 

Re-modelling - my understanding

by Gemita - 2023-11-27 21:31:30

Cardiac remodelling is a term that refers to changes in the heart's size and shape that occur in response to cardiac disease or cardiac damage. When doctors talk about “remodelling,” they are usually talking about the left ventricle, although it applies to other cardiac chambers too.  For example, the atria or the right ventricle.

I first heard about atrial remodelling in the context of my Atrial Fibrillation (AF).  The development of AF can quickly lead to structural damage (scarring and dilatation) and electrical (functional) changes to the atria, a process known as remodelling when abnormal atrial tissue substrate develops.  As AF progresses it continues to alter atrial electrical and structural properties and this promotes its maintenance and recurrence, hence the term AF begets AF.   However atrial remodelling due to AF can be reversed in some cases, providing we don’t stay out of normal sinus rhythm for long periods at any one time.  I doubt my episodes are causing undue harm since they are self terminating fairly quickly.  Longest episodes can sometimes be 8 hours+, but most episodes mercifully are only lasting minutes and I hope it stays this way.

Remodelling due to adverse affects of RV pacing may also be reversed in many cases, with resynchronised pacing.  

Remodelling for me means the heart has been injured and is often associated with ventricular dysfunction and serious arrhythmias with a poor prognosis unless it can be reversed or controlled.

Heart Remodeling Simplified

by DoingMyBest - 2023-11-27 21:54:04

My interpretation of the term is that remodeling means any reshaping, resizing, and/or change of function, for better or worse. I've seen it referenced in both contexts. But, to confuse matters, I've also seen some papers describe "reverse remodeling" or "inverse remodeling" suggesting a reversal of a previous change.