Looking for advice on settings

I'm now a little over a month post-implant (dual lead Boston Scientific L331) and have to say it's not going very well. My EP has been great, very responsive, etc., but to this point he's basically programmed 4 different modes with whatever their default settings are "guided by how I feel". And I'm a cyclist so I'll include that in how I feel below. 

The modes thus far (for those who are familiar with BS PM's) and the results have been:

DDD(R), rhythmIQ on - felt "OK" but not "good". Periodic episodes of lightheadedness but when I do have these episodes it's pretty pronounced (feel like I might fall), BP elevated. Felt pretty good riding. This mode paces in both the atria and ventricle and I was paced at 68/52.

AAI(R), rhythmIQ on - felt marginally better than above, no major episodes of lightheadedness but rather a consistent feeling of disorientation. Felt pretty good riding. This mode paces only in the atria. BP 104/70.

At this point, I did a session on a treadmill and it revealed I was missing v-beats until my HR got to about 118 then I was perfect 1:1 with no missed beats all the way to 147.

DDI(R), rhythmIQ on - felt REALLY bad, had to go back the same day. Nearly fell several times. In theory this mode should have been the best as it paces in the atria but only paces in the ventricle when I'm not active. 

DDD(R), rhythmIQ off - consistent lightheadedness though not severe. Feel terrible riding, really a struggle. When I go to sleep I feel like my heart is pounding and I woke up twice last night feeling nauseous. BP 130/80.

So the "guided by how I feel" thing with modes/presets isn't working.

Now my questions: how did you and your EP go about determining your settings? How long did it take before you found the right ones (if ever)?

Very frustrated to this point.

I have to say I'm envious of those of you who went in, had a setting change and immediately felt great. It seems that it takes me several days to come to terms with a setting change enough to where I can say it's better or worse unless it's REALLY bad. It also seems that my EP is basically going through different modes with whatever default settings those have.

TBH, I wish there were a more analytical approach than "how do you feel". The treadmill test was revealing but the programming based on the results were so far off that I don't know how to proceed.


Lots of Changes

by Penguin - 2023-09-02 16:14:57

I don't have the answers but here is some reference material. I am not familiar with the Rhythmiq algorithm.

Rhythmiq is described here:


Programming for exercise is described here: 


I suspect that the v.pacing is the tricky part.  To the best of my knowledge (and I'm not a medic), the AAI-DDD changeover settings (like Rhythmiq) which limit unnecessary v.pacing are indicated for sinus node disease but their effectiveness when there is AV block (the degree may be important) is less clear. Could this be the root of your issue?? 

I'm aware that my answer isnt that helpful. Wait for a cyclist with SSS & AVB to answer but I'd get the device Rep or an exercise cardio involved. 

Re: lots of changes.  You're 1 month into this and you've had your mode changed 4 times and you've had exercise testing.  Sometimes change itself can cause the symptoms and you have to wait for this to settle.

You could take advice on the most suitable pacing mode for your situation and stick with it for longer, making small adjustments to optimise how you feel along the way and feeding back. 

Sometimes it's a gradual process of elimination and trial and error.  

I hope you get this sorted out. 

I can feel your frustration

by Gemita - 2023-09-03 05:22:30

Aintgotrhythm, I would like to help you but I am not sure that I can.  Firstly have you had any follow up on the MRI findings of scarring in the basal to mid inferolateral wall area of your heart and when are you due for a PET Scan to rule out Sarcoidosis or any other inflammatory condition?  In the presence of a health condition which could potentially be affecting cardiac output and possibly triggering other disturbances, it might be difficult to see how any meaningful progress from settings adjustments alone could be achieved.

I have briefly familiarised myself with the Boston Scientific rhythmIQ algorithm which I see aims to minimise Right Ventricular pacing.  I can see there are some potential problems associated with this algorithm which can show a high rate of inappropriate switching (mostly due to PVCs) and also a high rate of induction of Pacemaker Mediated Tachycardia (PMT). The usual triggers for PMT are atrial and ventricular ectopic beats.

Algorithms to minimize ventricular pacing can occasionally have unintended consequences such as PMT. The PMT algorithm in Boston Scientific devices is associated with a high rate of incorrect PMT diagnosis during exercise resulting in inappropriate therapy and could be pro arrhythmic.  Cardiac devices cannot always differentiate between PMT and tracking of sinus or atrial tachycardia.

As an arrhythmia sufferer, I know that in the presence of rhythm disturbances getting our settings optimised can be extremely difficult.  I am still wondering whether you are experiencing arrhythmias which are causing difficulties and your settings may need more adjustments as a result.  Perhaps a trial of turning rhythmIQ OFF for a period might help to see whether your symptoms improve as well as looking at the Rate Smoothing algorithm.  You could look up Rate Smoothing feature in your manual and then work with your technicians to get this optimised for you.  It can help with any ectopic beats too that might be coming in fast upsetting pacemaker timing, but this algorithm can be difficult to optimise so you will need patience.

There is a member here who has optimised Rate Smoothing and it has been tremendously helpful for all her activities.  She has a Boston Scientific Accolade and is happy with it. She runs, bikes and plays golf. She doesn’t use the MV or accelerometer or rate response. She has heart block so paces 100% in the bottom lead during exercise but what really made the difference was optimising the Rate Smoothing algorithm, so if this is suitable for you, might be worth asking about and whether this algorithm is actually turned ON?  I think it is otherwise programmed OFF.

Looking specifically at your modes that have been tried, I see that AAIR is the one that suited you the most, particularly for cycling, so I would tend to stay with it and get that one optimised for you.  It is my mode for Sick Sinus Syndrome with intermittent bundle branch blocks, previous syncope, pausing.  I love being paced almost exclusively in the right atrium and atrial pacing certainly is an excellent treatment for some of my arrhythmias and helps to keep me stable.  I too hated going into DDI mode during mode switch to prevent the tracking of my high atrial rates during an atrial tachy arrhythmia.

I know you don’t like going by how you feel but it is all we have got to work with at the moment.  You need to be more in touch with your body. I wouldn’t compare yourself with others since you will have your own unique level of tolerance to your settings, to your heart condition or another health condition which might be present.  With a pacemaker, there is often a long period of trial and error until we hit upon the most effective settings for us.  It is a process.  This stage cannot be rushed.  I have been in your shoes and I am glad to say that finally I am where I want to be and I still have confidence that you will reach your goals too 

Current settings

by Aintgotrhythm - 2023-09-03 05:50:47

Thanks Gemita for your reply. My current settings are DDD(R) with rhythmIQ turned off and it's most definitely not working for me. It's Sunday on a holiday weekend here (Labor Day) and I expect my EP is unavailable but I am going to pursue just going back to AAI(R) with rhythmIQ turned on as thus far that's been the best. I see from the last device scan I have a report for that rate smoothing is on (Up 12%, Down 3%), I don't know whether that is the same with my current settings.

Right now (it's 03:00 here) I've awakened in the middle of the night feeling nauseous, this is the second night in a row that's happened so almost anything seems better. At this point I'm worse than pre-implant.

I should explain my dissatisfaction with "going by feel". At least to this point, when any changes to the settings are made I don't instantly feel better or worse. The worst settings thus far have been DDI(R) and it took several hours before I could say they were worse but there were really worse (losing my balance and nearly falling). As a scientist myself (though no medical training) I can't believe there's not an objective way of measuring response to various settings to arrive at the best result for an individual.

As I said previously, the current approach is to change modes and use whatever the presets are for those modes. I'm certain these presets were derived from a lot of clinical data and work for the majority of people. They just don't work for me.

I believe a session with my EP and a Boston Scientific rep is needed and that's what I'm going to pursue but given the holiday it's not likely to happen immediately.

And my PET scan isn't until Sept 8. I'd previously messaged my EP giving my symptoms and saying I'd wait until after the PET to make changes but given how I feel now that's too long.

Thanks for your reply and I'm very happy you're "where you want to be" - hope I get there!

Rhythmiq for AV conduction disorders

by Penguin - 2023-09-04 05:33:04

Hi Again, 

PMT can make you feel quite nauseous.  PMT occurs mainly in DDD mode which may be why you are feeling unwell currently.  

This may not be useful, but a search for info on Rhythmiq brought up a problem ECG in a Q&A session. It referred to the use of Rhythmiq when there is an AV conduction issue, so I've copied the relevant answer for you: 

'The RYTHMIQTM algorithm aims to minimize right ventricular pacing and has been implemented in modern Boston Scientific dual-chamber pacemakers and implantable cardioverter-defibrillators. When the atrioventricular conduction is preserved, the RHYTHMIQTM algorithm operates in AAI mode with VVI back-up pacing and switches to DDD mode if a loss of atrioventricular conduction is suspected. While in DDD mode, the AV Search +™ algorithm is used to search for restored atrioventricular conduction with periodic automatic extension of the AV interval. By design, the algorithm cannot switch from DDD to AAI without this AV search+ phase (basically 300ms AV delay, looking for 25 VS but stops if 2VP within a rolling window of 10 ventricular cycles).'

This is from the cardiocases website again. 

Do you have the AV Search+ algorithm turned on alongside Rhythmiq? Silly question as it sounds as if they go hand in hand, but you never know!


Yes, AV Search+ is on

by Aintgotrhythm - 2023-09-04 11:18:23

Thanks for the additional info! I've been browsing around the cardiocases web site and had noticed this.

Yes, AV Search+ WAS on, Search AV Delay is 400 ms, Search Interval 32 cycles

I emphasize "was" because the current settings have RythmIQ off and that's totally not working for me. I'm hoping to go in tomorrow (holiday here today) and get the settings changed to AAI(R) with RythmIQ on which will restore the AV Search settings.

Thanks again for the follow up!

AV Delay

by Penguin - 2023-09-04 15:45:35

400 ms is a very long AV delay. Again, it may be due to a set up I know nothing about but you might like to enquire about that?  450 ms is the max on my device and my previous device and my consultant didn't speak terribly favourably about that length of delay.  Clearly it may be helpful for you - but check. 

AV delay (if you don't already know) is roughly like a PR interval (time to get from Sinus node -> AV node).  

Lots of maybes - sorry - but perhaps a starting point for conversations. 



I was in your boat.

by PacedNRunning - 2023-09-04 17:47:54

Let me first start off by saying. Only change one thing at a time so you know what is causing what. Some settings we turned off, I ended up trying them again and it worked. So don't think if you turn if off you can't try it again. 

I also have a Boston. I should look to see what your reason for a PM Is. My is for heart block. 

if you exercise turn off Rhymiq and AV search. A search cycle of 32 cycles while exercising means it's checking for intrinsic more frequently. The faster your HR, the quicker the cycles come up for checking. It can be as long as 1046 I think. I can't remember all the numbers. It's been a while since I had to adjust those settings. Since I have AV block every time thr search cycle came up, I got punched and then immediately out of breath. I found having it off best. The reason it's 400ms search cycle is because it will allow intrinsic beats  to be found if it's shorter say 300ms, the less time and more likely won't find it and causing more pacing. So the 400ms seems long but reasonable for search cycle. 

rate smoothing up/down. Love that setting for me. That was the final piece of the puzzle for me. Reps weren't use to using that setting so at first they had both up and down on. I will say having both on is not good. At least for me. Your heart plays ping pong and made me nauseous. I only have rate smoothing down on. We started at 18% and finally felt the best at 6%. 9% wasn't bad but it stopped those hard breathing episodes while running. 

Best advice is keep taking notes with each change. Even though you don't prefer this. Do small changes. Hopefully they can get you to a tolerable place And then make small adjustments from there. 

What is your lower rate limit? 60? 50?  Also rate smoothing should be used if you are having sinus arrhythmia or dropped beats. I had dropped sinus beats while running because my P waves got smaller. 

I just know with exercise Rhythmiq 👎🏼 and AV search 👎🏼. If they want to limit V pacing then I would suggest have AV search but change the search cycle longer. 1042 something like that. So instead of it checking every 3 mins it would check every 15 mins while exercising. 

Let me know if you have any other questions or need clarification. I'm happy to help. I went through ALOT of changes. I've also been allowed to experiment with different settings, so I kind of know what causes what. Not always but definitely a good amount. Waking up at night with nausea 👎🏼. Mainly because of the rate smoothing up and down. That ping pong HR while resting. 

Thanks penguin and PacedNRunning

by Aintgotrhythm - 2023-09-04 19:21:14

Thank you both for your comments. To address some of the points you made:

As PNR noted, the 400ms AV Delay is during the search cycle when it's missed an intrinsic beat. The normal paced/sensed AV Delay setting on my PM is 140-280ms.

I do keep a journal of all of the changes and how I feel with each one. As I've said, to this point the EP/device tech is just doing modes/presets and not changing individual parameters e.g., rate smoothing but I do believe that's an important next step. The first one though is to get a baseline mode that "sort of" works to use as a jumping off point. Based on the mode settings used thus far I believe AAI(R) is the right one.

My LRL was 55 and at the last go-round they changed it to 60. I believe this is too high. My resting heart rate has been low (45-55) all my life so a setting of 50-55 would feel more natural I think.

I believe (I've not seen the report from the current settings) rate smoothing is currently set at 12% up, 3% down.

Thanks once again!


by PacedNRunning - 2023-09-04 20:10:45

You are exactly right with the AV search. Maybe try extending the search cycle longer.   Next, I would either pick up or down for the rate smoothing. This setting was intended for afib. To help with sudden increases in HR and sudden slowness from Afib. So it's good to know if your HR is speeding up to fast or slowing down too fast. Ive talked to a few others with this setting and they too have found one or the other works. Up or down. When I did the treadmill session we saw my HR go from 160bpm down to 70 then back up. So rate smooth down works. But if you are seeing your HR swing up way 150 to 180 then perhaps rate smoothing up. I would recommend trying turning one off and not have both on. 

Since you have chronotropic incompetence, 60 lower rate limit is probably best. Mine is 45 but I don't have CI. But if you do 60 is a better rate to start at Vs 50 for you. Hope that makes sense. It's mostly because the device doesn't respond that quickly when you go from sitting to standing etc. 

the next question is do you need V pacing? You will want to know that because if you don't need that pacing, your AV delay 140-280 seems reasonable. But if you need it with exercise it may need adjusting. Again, one thing at a time. I hope they can get you to a tolerable place for now and then make small changes. I would first try the rate smoothing. Pick up or down and then figure out the percent that feels good. 

Thanks PacedNRunning

by Aintgotrhythm - 2023-09-05 04:44:52

Thanks for your reply. One comment: I'm not sure about the chronotropic incompetence diagnosis. I put it in my profile and the first cardiologist added it to the report of my visit with him but I think he based that on a comment that I made during the visit rather than any diagnostic result.

The comment was that earlier in the year I had a hard time reaching my max HR and that at the time I put it down to "not having the legs" to push my heart that hard while riding. I was recovering from an injury (unrelated to my heart) and during hard efforts/intervals I'd be unable to continue the effort past a certain point. I think my diagnosis (not having the legs) was perhaps the correct one as no other tests including an exercise stress test revealed CI.

As to the V pacing - I don't know. As I mentioned in a previous post, during my initial consult with my EP he said that based on my test results I "didn't need" a dual lead PM but recommended I have one implanted anyway against future need. He turned on the V lead and I am paced in the ventricle when the PM is set to a mode with V-pacing but to be honest all of those modes (see summary in earlier post above) haven't worked well for me. I've felt the best in AAI(R) which does not pace in the ventricle.

The journey continues...

Well keep us updated!!

by PacedNRunning - 2023-09-05 16:44:36

I understand your frustration. Maybe your not frustrated but I did my best to stay as patient as I could because they kept telling me they were not use to young active people with pacemakers.  If you feel better in AAIR mode then I would think the Sinus node is your issue.  You may be able to increase your HR but can you meet the max predicted for your age?  You may have a long PR interval and hence why you pace in the ventricle with DDD mode.  Typically when we are active we have a high vagal tone that can cause prolonged PR intervals. So you may not need the pacing support but because your PR may be long, it can't out beat the PM.


 They key for progamming is knowing where you need support because if you are saying you don't have CI, then AAI may feel better without the "R" rate response. You may not need R at all.  I know for me, they. had the R on for me and I felt really out of breath and could barely walk let alone run. They ended up turning it off for me.  Hang in there! I'm sure they will get it right soon.


An update

by Aintgotrhythm - 2023-09-07 10:00:55

I wanted to give it a couple of days to see how the current settings were working for me before giving an update - thanks to all of you who have been following along for your patience!

I went in and saw the device nurse. My settings going in were DDD with rythmIQ turned off, LRL of 60. I'd previously felt best with AAI(R) but had only been at that setting for 48 hours. I had the mindset that I was going to "demand" being set back to that since a) I felt terrible with current settings and b) that felt best of what has been tried.

The nurse changed the settings to AAI(R) and I immediately started dropping v-beats. A *lot* of v-beats (maybe 20%?). She had me do a lap around the clinic and come back and although better I was still dropping v-beats.

Lengthy story short, after several changes/laps I'm at DDD(R), rythmIQ on, LRL 55, activity level "athlete". There were some other changes to the timing parameters but I've not seen the report yet so don't know what they were.

I went for a 42 mile bike ride yesterday, moderate effort (avg/max HR 105/142).

Results: I certainly feel better than with previous settings. I didn't wake up nauseous in the middle of the night and slept reasonably well (for me). Have persistent low grade lightheadedness, not debilitating but present. BP is elevated (128/72) but not to the same degree as before.

During my ride I generally felt OK (this was the first "moderately hard" ride I've done in a while and the longest so I'm somewhat deconditioned) but did notice some puzzling behavior. On an extended climb my HR was a steady 130. I pushed harder for a bit (175 watts steady increased to 225 watts) and noticed my HR went DOWN to 120 for about 10 secs then went up to 138-140. 

So end result is "better" but "not there yet".

Device nurse is trying to set up a session with the EP and the Boston Scientific rep present and me on a treadmill. I was supposed to have a follow-up appointment today but she called yesterday to ask how I was feeling and said she was going to cancel it because she didn't know what else to try.

The change in HR

by PacedNRunning - 2023-09-11 01:41:05

The change in HR from 138-140 to 120 could have been the rhythmiq checking for intrinsic. Rate smoothing may not available during this rhythmiq check. I couldn't tolerate rhythmiq or rate hysteresis  during exercise. 
 I did the treadmill session about 7 mos post op. My setting were fairly tolerable at about 4 mos post op. It was helpful because that is where we caught the rate smoothing needed to be shorter percent of change for down.  Hopefully the treadmill guide them to make adjustments. Or perhaps on a bike since you bike. Heel strike is different for accelerometer vs biking. 

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