Modeling Boston Scientific's RightRate Pacing Algorithms

Hello Everyone:

I am posting to see if anyone can help me develop a model that will replicate the pacing that my BS Accolade pacemaker produces when I am exercising -- specifically when riding a road bike.

BACKGROUND:  Three years ago I was diagnosed with AFIB, and have gone through two ablations.  I am now on beta blockers -- to protect against recurring SVT's -- which are causing a lowered heart rate.  Last July my cardiologist implanted the BS Accolade pacemaker to protect against brachycardia.  It is programmed in DDDR, with both the Accelerometer and Minute Ventilation RightRate pacemaker programs being active.

THE ISSUE: I have recorded (and saved) my heart rate data during cycling since 2002.  After starting on the beta blockers (metoprolol) I immediately noticed that I couldn't get my heart rate to respond on demand.  My three pacemaker followup sessions with three different BS field reps were a disappointment - since none of the three were familiar enough with the RightRate settings to address my issue.

PROGRESS:  I have researched Chronotropic Incompetence and have also studied the RightRate programming manual and the programming workbook, both of which are available on the BS website.  While neither of these resources provide enough detail to replicate the BS model -- with a few assumptions -- I have a developed crude model that is a "first go,"  and was at least good enough to get one of the RightRate settings changed.

HELP DESIRED:  My questions are two: (1) Has anyone tried to do this or does anyone have the RightRate models that I can use; and (2)  Is my approach to getting what I need the right one?

Thanks!  Bill


14 Comments

Model

by AgentX86 - 2022-04-28 13:39:38

No, I don't believe your approach is going to get what you need.  You need a knowledgable BS rep.  I don't know anything about BS but Medtronic has local (sometimes dedicated to one hospital) reps, regional reps, and the experts at their "headquarters".  Each in increasing knowledge of the pacemaker and how to tune them. I can't imagine that BS doesn't have a similar hierarchy.

IMO, there are too many unkown variables to make a respectable model of RR and your response to RR.  It is a feedback system which can quikly become very complicate.  Throw a beta blocker into the gears and I think you're barking up a tree.

BS Accolade for cycling

by nickhu - 2022-04-28 17:39:48

I had an Accolade implanted in February this year, partly because of the ventilation pacing it offered, I've been a cyclist all my life.  It was very disappointing when my heart rate still wouldn't go up above 108 when riding on the trainer when I first started trying to ride again, despite  it being set to 150bpm max.  I mentioned it to the Dr and they adjusted the setting for how quickly the PM reacts from 8 to 12 and it was like rocket fuel - my HR responded and went to 150, my power when climbing at a tempo type effort was easily 30% more than before, I had the biggest smile on my face.  I did notice though that sometimes it doesn't kick in and I get stuck at 120bpm.  Reviewing my garmin data suggests that is linked to my breathing rate (150bpm = 40+ breaths per minute, 120bpm = around 30 breaths per minute).  I need to experiment more as I anicdotaly don't feel like my breathing is that different, possibly it is picking up cadence as breathing, not sure.

Not sure that helps but my recommendation would be to speak to your Dr and PM tech and try out some adjustments.  As a cyclist myself I know we are used to tinkering and seeing results ourselves with equipment, training etc and we are control freaks but I don't think trying to second guess the PM is going to get you anywhere.  There seem to be too many variables and I doubt it would be of any use anyway - the Dr and Tech hold the keys so you can't tweak it yourself anyway.

Good luck

You need a tuning session on a static bike

by crustyg - 2022-04-29 03:09:14

Also a road cyclist.  My lovely EP-doc setup a session about 5weeks post implant to tune my Accolade.  I did five separate 'runs' on the bike and we got the box tuned perfectly for me, validated by my extensive HR data when cycling out on my own and in a group (i.e. not all maxHR for 3hrs and plenty of spikes to maxHR when needed with sensible mid-range HR on gradients).

Five runs: because, if you read the docs carefully, MV can be deactivated for a couple of minutes after each programming - which is how you change the settings.  Also, you need to use Zoom comms during the runs as the big magnet/inductive coupler interferes with MV - and ideally, if you can, find a static bike that's not magnetically braked, as MV input is *very* sensitive to magnetic fields.

BostonSci rep was very good, my EP-doc left him and the EP-tech to do it all.  After a bit of playground macho-man alpha-male posturing at the start we got on very well, and made sensible contributions to the process: EP-tech admitted to having learnt a lot from the session.  Get hold of the BostonSci Brady Reference Guide - it's easy to find on the Web and well worth the read.

Send me a PM if you wish, and I'll happily share what I know from 3years of road cycling with Accolade.

Thanks for Your Inputs!

by bill70j - 2022-04-29 10:24:53

First, thanks nikhu for relating your experiences.  Amazingly, the one setting we have changed is the MV Response Factor - where we went from 8 to 12 - exactly as you did. I also saw a much quicker and higher response, but in my case I now reach the Maximum Sensing Rate of 160BPM with about 60% Perceived Effort.  So on a 3.5 hour ride, my heart rate averages ~155, which is ridiculously high.  So this needs to be tweaked, plus the other settings - four for the Accelerometer algorithm and the other three for the Minute Ventilation algorithm need to be set correctly (including the "Ventilatory Threshold" and VT Response). 

Second, thanks crystyg for relating your experience and advice. The electro physiologist who did my ablations quit and left the area.  My cardiologist implanted the pacemaker, and while I like him, I am not sure how familiar he is with the Rate Pacing routines of my pacemaker.  I have found a new EP who is attached to a well known medical institution not far from here, so I will contact him and see about setting up the sessions you describe, to include both a BostonSci sales rep as well as a clinical technician.  (By the way, the BostonSci rep in my last session had an "attitude"  as well.)  I had bookmarked the two Brady Reference guides you mention-- now I need study them.  And thanks for your offer to share your three years of learning.  I will PM you. 

I feel I now have a sensible approach for getting what I need from my "box".   But I am still going to pursue modeling this system - just because.

further updates

by nickhu - 2022-05-02 16:58:06

Please let us know how it goes Bill70j.   I was out again over the weekend for a big MTB ride and when the pacemaker hits 150 - boom, its like a turbo, but when it doesn't and gets stuck at 120 it is miserable.  In fact on one climb it was 107, 110, 120, 110 etc.  I tried riding erratically, breathing super fast, resting my left hand on my knee while pedaling (not easy on 10%+ grade!)  and it would go up for a few seconds then drop back down.  I'm sure the ventilation sensor is picking up my cadence instead of breathing rate but I'm still not convinced that this is the full story, very frustrating.  Bottom line is though that I'm not complaining - my quality of life (and exercise/recovery) is so significantly better now this is all cherry on the top and when the turbo does kick in it is amazing :)

Further Updates

by bill70j - 2022-05-03 10:41:19

Will do, nickhu.

Sounds like a you are in a very frustrating situation.   That's how I felt also, and is why I am making every effort to understand how the Boston Scientific RateRight pacing works -- to include modeling the algorithms.  Obviously I am not going to program my Accolade, but I want to be able to get into the details with the BostonSci. technicians during my upcoming session so we can discuss exactly how the pacemaker can be configured to satisfy my needs during exercise.

With that disclaimer in mind - here are some of my comments on your situation, for what they're worth, and an update on where I am with modeling the system.

First, if you haven't already done so, you may want to read and study pages 2-26 through 2-52 of the document in the link below.  It goes into fair detail about how RightRate pacing works, and the significance of the major settings.  You had mentioned that your MV Response Rate setting is 12 - and so is mine.  I will list my other RightRate settings below and have included in Members Only>Member Gallery>bill70j trends of my heart rates during four bike rides (which were downloaded from STRAVA into Excel).  Maybe comparing your trends with mine wll give you a data point to play with.

https://www.bostonscientific.com/content/dam/Manuals/us/current-rev-en/359239-002_multi_RG_en-US_S.pdf

Lower Rate Limit

60

 

 

Max Tracking Rate

135

 

 

Max Sensing Rate

160

 

 

Accelerometer:

 

Minute Ventilation

 

Response Factor

8

Response Factor

12

Activity Threshold

Medium

Ventilitory Threshold (VT)

110

Reaction Slope

12

VT Response

70

Recovery Curve

8

Fitness Level

Active

Your thought about breathing rate being an issue certainly sounds plausable, since changes in Minute Ventilation (short term MV average vs. Baseline MV) drive pacing rate.  So properly sensed breathing rate (and tidal volume) plus proper Baseline are critical, but so are Ventilatory Threshold and VT response, along with the Accelerometer slopes and curves.

As far as where I am with modeling, I have completed a very basic (and crude) first draft model that calculates a sensed rate as a function of delta MV, Ventilitory Threshold, and VT response.  The MV is empirically derived by feeding the model data from a recent bike ride, and calculating a single MV from a breathing rate and estimated tidal volume during a period of known and constant heart rate.  A simple chart showing results from the model are included in Member Gallery.

I stll have a lot of work to do, specifically working the effects of the Accelerator data into the model.  My major challenge is modeling all of this using Functions in Excel.  If only they would bring back Fortran!!

Paced Beats

by dogtired - 2022-05-03 22:03:31

This thread is interesting, and I certainly understand the desire to perform better, but I wonder if forcing your heart to beat faster actually shortens your life span? Can a defective heart be forced to beat without limit?  I would think at a minimum it must depeat the battery faster.  Is the price for finishing 99 vs 150 worth it?

Great thread

by Gemita - 2022-05-04 03:16:09

Bill, cannot add to the excellent advice already given for your question (1).  

Question (2) I see you have had several ablations and are on a beta blocker to protect from atrial tachy arrhythmias.  I have noticed some athletic members cannot tolerate even small doses of a beta blocker which affects their ability to exercise but seem to do better on a calcium channel blocker, so maybe worth asking your doctor about this if your own attempts with settings fail to help overcome your difficulties.  

Personally as an arrhythmia sufferer, once a tachy arrhythmia starts I would have difficulty maintaining any form of exercise, so my advice would be to try to ‘moderate’ exercise wherever possible rather than to always push to our limits. I appreciate this will not be easy for a trained athlete to contemplate but moderating exercise now may help to hold off the potential progress of any arrhythmia.

Dogtired.  Your question would make an excellent new post, since we all know the benefits of exercise but we are also becoming increasingly aware of exercise induced arrhythmias.  I don’t think though we are talking here of forcing the heart to beat without limit, only to increase capacity during the period of exercise.  I see Bill’s Base rate is set at 60 bpm, so during periods of rest his heart rate is certainly not being pushed.

Thanks for Additional Input

by bill70j - 2022-05-04 10:58:17

dogtired  Very good questions.  I am trying to get my heart to perform better during exercise -- but am looking only to restore its performance to where it was before I was put on a beta blocker medicine.  My max observed heart rate during 90% perceived effort was 155  before the meds - and dropped to 125 post meds, which made exercise (in my case road cycling) far less enjoyable.  Thus my interest in this subject.

As far as finishing 99 vs. 150 - that was certainly relevant 20 years ago when I was riding in a traditional competitive bike club.  Today my rides are mostly solo, and I ride simply to stay in shape and to feel better.  My gage of how well I am riding is to compare my rides to virtual riders in my age group on the same courses (contained in the STRAVA website).

Gemita Thanks for your keen observations.  During the last session with my cardiologist we talked about switching from the beta blocker (Metoprolol), which was prescribed by my electro physiologist, to a calcium channel blocker (Diltiazem).  I am using up the last of the Metoprolol  so will be switching soon.  He is also hopeful that the Diltiazem will be more effective in controlling hypertension - so a side benefit could be dropping the med I am taking for that.  We'll see.

My EP told me exactly the same thing about being careful not to over-tax the heart during exercise.  In fact he was giving free lectures to local bike clubs warning them of "over-doing it," citing a statistic that over 50% of pro cyclists and competitive rowers suffer from some sort of arrhythmia.  This is the only comfort I feel about my situation - I have done it to myself!

Nickhu  I keep thinking about your situation.  I wonder if your Ventilatory Threshold and your VT response are set too low.  If they have you at 110 and 55%, that would mean that any time your heart rate gets above 110, your response factor would, in essence drop to 0.55X12 = 6.6 -- even lower that your original 8.  Just a thought.

Settings

by nickhu - 2022-05-06 18:48:00

Hi Bill70j, a lot to take in here since I last check the thread.  From looking at the info the Dr provided me with at the hospital, I don't have all the settings data you have listed, including the VT response but I will ask next time I go in.  I do know my min HR is set to 50, max 150 and they changed the accelerometer activity threshold from medium to medium low and the minute ventilation response factor from 8 to 12.  

Below is a link to a recent road ride I did where you can see pretty clearly where the pacemaker is going to the max and where it isnt.  You can see from about 40mins to 1hr435mins it was a pretty constant climb - the first half I couldnt get my HR up, then after a slight easing of the gradient - bingo.  Its weird because I feel like my cadence and breathing rate would have been pretty much the same for all the climbs - they are all similar gradients but that part sticks out like a sore thumb, check it out.

Dogtired - WRT to finishing 99th vs 150th, a max 150HR is still low compared to most my age and I checked with my Electrocardiologist and she said no problem.

https://1drv.ms/u/s!Ap0mnUy4aKDAgYBojN9ORN8Fey5qOg?e=zeYLtz 

Settings

by bill70j - 2022-05-07 13:54:04

Nickhu:

Yes, I see what you're saying about that strange drop in your heart rate during a climb that is shown on your chart.  I wonder if you have power data (real or calculated) that you can insert into that chart?  I have also seen my pacemaker do exactly the same thing.  (I have put that heart rate chart into the Member Gallery.)  Still very mysterious.

My initial thought was that the cause might be your Ventilatory Threshold and VT response settings, but I played around with those settings in my (yet crude) model, and it indicates that at most those settings could influence your HR by 10 PPM.

Below are the outputs from the model, based on a look at respiration rates and heart rates from your chart. You can see that the predicted heart rate results in the last column are nearly identical to your actuals.  It indicates that, for some reason your respiration rate doesn't support a higher heart rate, but as you say, your perceived effort was the same during all of those climbs, so something is strange.

Please keep us informed as you explore further - and I will continue fiddling with the model - your data is very helpful!

 

Model Results - Using Input Data From Nickhu's Chart

Heart Rate PPM

Respiration, BPM

Tidal Volume

litres

Minute

Ventilation

 Predicted

Heart Rate

(Notes)

60

15

0.50

7.50

60

150

43

1.75

75.25

153

110

30

1.25

37.50

109

Notes:

HR=1.639*MV+47.7

Formula Applies From Rest To Ventilatory Threshold

HR=1.149*MV+66.3

Formula Applies From Ventilatory Threshold To Max HR

      

 

Model Settings

Response Factor Constant

1.64

Tidal Volume at Rest, liters

0.50

Respiration Rate at Rest, BPM

15

Minute Ventilation at Rest, l/min

7.50

Baseline Initial Period, Hours

4.00

Heart Rate at Rest, PPM

60

Lower Rate Limit, PPM

60

Ventilitory Threshold, PPM

110

Ventilitory Threshold Response, %

70

 

 

Update

by nickhu - 2022-05-18 18:14:20

I do have power but I didn't show it for simplicity.  Basically it is a totally fixed relationship 150bpm I can go to threshold (approx around 250w, I haven't tested for a long time) and above without too much trouble, but when my HR is pegged to 120 then anything over 180w for more than 20-30secs I will have to stop to recover.  I hadn't seen the manual link you sent me, but  have read through it now and it sounds like there are some adjustments that might help.  I have an appointment at the clinic in a week.

In the meantime I raced my MTB at the weekend, HR stayed up the whole race and I won my category by 4 secs!  I was super surprised and happy I can tell you, my last race (January, before pacemaker) I had to stop three times to recover and finished dead last, I hope its not considered cheating....

Congrats on Your Win

by bill70j - 2022-05-20 10:25:34

Nick:

Nice win!  

As far as pacemakers go - we have the same issue.  When the pacemaker mysteriously reduces paced rate, seems there's nothing one can do to get it back up - except wait. (Not the ideal  cheater!)

Please let us know how your appointment goes with the clinicians.

Bill

Thanks bill70j

by nickhu - 2022-05-27 12:36:09

Re reducing paced rate, this thread also discusses that issue:  https://www.pacemakerclub.com/message/41681/rate-response-of-pacing-feature-stops-working-after-50-or-so-minutes.

I rode 2hrs on Wednesday and it happened twice.  Stopping for a minute or so and then riding high cadence out of the saddle when restarting definitely kick started the pacemaker back into operation. Fine for solo rides but not practical for group rides or races.

I'm off to the pacemaker clinic this morning to get some adjustments and have a 5hr sufferfest planned for tomorrow so we will see how it goes!

Nick

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Member Quotes

I'm 35 and got my pacemaker a little over a year ago. It definitely is not a burden to me. In fact, I have more energy (which my husband enjoys), can do more things with my kids and have weight because of having the energy.