Pacemaker setting optimization

I had a Boston Scientific Dual Chamber PM placed in June. It's purpose was to address symptomatic Sick Sinus Syndrom producing long pauses of asystole. I also have A-Fib and a 1st Degree AV block and PVCs. This is a difficult combination to deal with for any cardiologist. I have two good ones, An EP Cardiologist and an excercise oriented Cardiologist. I had a very successful Cardiac Ablation in August that, so far, has enitrely eliminated A-Fib. I am 75 and a long time amateur competative cyclist that has migrated to indoor spinning. Roads are just too dangerouos anymore.

Here's my question: my PPM was set to ventricular pace when intrinsic heart rate was below 60 BPM. At last device check, it paced 100% of the time. Max pacing rate was set at 140 BPM and I could comfortably reach that max rate via respiratory rate response while spinning (pushes through the AV block). Yesterday, after discussing my experience, my EP wanted me to try "going it on my own" which meant my PPM would only pace if my HR dipped below 40. He explained I really didn't need continuous ventircular pacing just needed it on demand when HR dropped to a level where, if continued, sycope was likely. Today I cycled and, as before the PPM placement, my HR would not accelerate above the ninetys. That was due to my AV block and chronotropic incompetence, not necessarily relieved by a PPM. The ride was no more challenging than when the PPM was pacing and I could get to 140 BPM. I know, seems weird.

It appears that  I have to choose between two options: (1) Continuous pacing that eliminates chronotropic incompetence and HR to 140 or deal with the chronotropic incompetence to avoid continuous paceing. Anyone else dealing with a tiuation like this?


Pacemaker settings

by Selwyn - 2023-09-07 17:22:46

Yes, I have a Boston Scientific. I've had my tweaked this week as I did not like ventricular pacing at 100 bpm when just walking up a flight of stairs. I was told by the EP tech that they do not like the ventilation setting except for competitive cyclists ( I have now heard this from three independent EPs. ). 

I have had the blanking period altered ( lengthened)  to try to give my atria some chance to function ( DDDR setting)  - with ventricular pacing at 100 there is no chance of atrial activity and this results in a poorer ejection fraction/stroke volume. The result has been some improvement with shortness of breath on going up a flight of stairs. As this is only my second day since the PM was tweaked I will see how this goes. Certainly, playing table tennis this evening seems to be a bit better.  I will see how thing go with some more strenuous exercise ( swimming) .

 I think that if you can cope with a bit of physiological pacing you are at an advantage, compared to  total ventricular pacing where there is some asynchrony between the atria and ventricles. This eventually can lead to heart failure. 


by jbuch002 - 2023-09-07 18:16:17

Thanks Selwyn. I'm set at DDR40 and yes, I want some physiologic pacing to get my HR above 90 but it seems I have to choose between ventricular pacing starting at a lower value (e.g., like it was intially set at 60) and it pacing at 100% or none at all. I was led to beleive it is either or and that there was no way for the PM to fix my AV block that won't let my HR get above around 90. It's also worth noting that I have a very large variance in R to R. Devices I uses to track HR read these variances as reduced HR (e.g., I'll go from 104 to 76 and back to 98 and so forth with skipped beats preoduced by the AV block. I'll keep working on this with my care team.


by crustyg - 2023-09-08 04:30:13

I'm also a cyclist (still out on the roads) with SSS+CI, with Boston Sci L331 and dual leads.

My EP-doc thinks that the fibrosis that has destroyed my SA-node will eventually affect the AV-node, hence dual-chamber PM and leads.  Unhappily my RV lead is right down at the RV-apex so it's a long time away in terms of signal detection by A-lead and watching for signal detection in V-lead: initially I was set to RythmIQ, BostonSci's attempt to provide the minimum of V-pacing for SSS patients who might need some V-pacing support.  This meant that maxHR was 145BPM, which wasn't nearly enough for me.  Had I been fitted with a His-bundle RV-lead a higher maxHR might have been possible (much shorter time between A-signal and V-signal => ability to initiate another pace without risk of triggering VF).  At present I'm 100% A-paced and able to get the HR that I need (almost all of the time).

I'd be interested to know if your team have tried you on RythmIQ: in theory this would be the answer for you.  MV - on, driving up your HR from the RA, and your PM able to switch to DDDR when required and then switch back automatically.  A lot of A-pacing isn't going to cause issues for you and with 1st-degree AV-block you might just be able to reach 140BPM from A-pacing.

Have your team discussed your settings with the local BostonSci rep?  Perhaps I'm lucky, but my local BostonSci rep is really good and helpful (he did the initial bike tuning of my PM) and it turns out that he's very athletic which aids understanding.

Send me a PM if you're not comfortable sharing settings in the open.

Best wishes.


by jbuch002 - 2023-09-08 13:41:53

Thanks for the post crustyg. Yes, before my EP set the PM to DDI 40 yesterday, it was set at DDDR, RYTHMIQ on, MV on low base rate 30 ppm, upper rate 140 ppm. The outcome was 100% V pacing. I complained about reduced EF, AV Asynchrony and risk of heart failure over time at 100% V pacing. He agreed and said, fine, "IYou really don't need V pacing, 'll set your PM so, you'll be on your own. You'll only get pacied if your HR drops below 40." I didn't get if the PM will auto switch back to physicologic pacing and at what point or any other settings. I only have the PM report before he changed settings.

Yes, the Boston Scientific rep was there for my first two device follow-ups (differnt reps). Two competent techs, IMO. No tech this most recent visit, yestereday. All of my team know I spin and am naturally competative, esp. on bikes that are metered (CycleBar). My EP is managing several cyclists with PMs so, he's supportive.

I've had a long term aysmtomatic first degree AV Block, devloped symptomatic A-Fib at 65 and since March of this year, developed symtomatic (near sycope) SSS (long V pauses = HR 30). I had a concurrent signficant drop in spin performance (endurance) objectively and subjectively. After PM placement with inital setting  as above (not yesterday's new settings), I was able to get my HR up to 140 (220 - age = 145). That was unsustainable but could sustain 125-135 for 4+ minutes with leg muscle fatigue the show stopper which I attribute to limited endurance. Is this detraining from the regular spin events I missed for a good 3 weeks or reduced EF as a result of PM settings. Favor the later but likely combo of both. WIth the new settings, I'm back to square one with shitty endurance and obvious AV block/delays negatively affecting HR.

I'm just starting to get familiar with the incredible capabilities of the Boston Scientific PMs. I feel like I have a good team. Still, I'm not convinced my settings are optimized and my age appropriate brain atrophy makes it difficult for me to understand what all the settings do. 


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