Functioning of sensors Boston Accolade versus Boston Proponent

Hi and welcome

by Lavender - 2024-08-19 22:32:16

I have a three year old Boston Scientific. I found that calling the manufacturer is very helpful when I have had technical questions. 
I don't know if this is helpful for you but you may have been given contact information for them in your country. I found this online:

The phone number for Boston Scientific in the Netherlands is 0800-0292077.

Netherlands

customerservice.nl@bsci.com +31 045 5467684

You have a complex history of arrhythmias

by Gemita - 2024-08-20 01:40:01

Heike, thank you for your post and I am so sorry to learn that you are still looking for answers for your symptoms.  I hope I have understood your message and Bio history correctly.  

I see you have an extensive history of implant/explant of pacing systems, of complex arrhythmias requiring multiple ablations, as well as a history of thyroid cancer and of pacing induced arrhythmia.  Frankly, I am not surprised to learn that you are still having pacing difficulties. In the presence of rhythm disturbances you will need to be very patient and it will take longer to get your settings adjusted to suit you.

Since you have already been told that the accelerometer sensor for both Boston models L211 and L311 should work exactly the same, this might well be true.  Perhaps your doctors will need to look elsewhere for answers and I would go back to them and describe your symptoms.  Your need for an early settings change could perhaps also be due to a change in your heart condition?

When did you have the implant?  If it was recently, you may need to wait at least 3 months for things to settle.  They don’t usually like to go rushing in and make changes to settings too quickly or to change too many settings at once since sometimes our symptoms settle without intervention.

I note you had a Reveal Linq monitor implanted in 2018.  I presume that has been left in place, although won’t be working any more.  Mine had a battery of 3+ years.  I had mine explanted, but they don’t always remove it during our life time. You could ask for longer term monitoring to try to identify any new rhythm disturbances or pacing induced changes as a cause for your present difficulties?

You mention there are differences between the L211 and L311 and that these differences lie in a few parameters rather than in the settings.  These parameters will be set by your electrophysiologist so these may need increasing or decreasing, but only long term monitoring and patience to get these parameters finely adjusted to suit your heart condition and lifestyle will help.  The Boston pacemaker seems to have many excellent features, but with complex features like sympathetic/parasympathetic autonomic balance monitoring, I can imagine just how difficult it will be to get these settings optimised.

Your questions (in bold): 

Do the sensors work differently when you got the same device and this is not exactly in the same place as the previous one, even after calibration of the MV sensor?  

Your replacement device was presumably placed in the same pocket, under the muscle as your old Boston device?  Your leads were then re-attached, so there should be no change, unless your leads are malfunctioning or something like this?

Or does the Proponent respond slightly differently to the settings than the Accolade because of the 2 different parameters? 

If the new pacemaker has additional parameter settings that need adjusting, getting these finely tuned to suit your needs will make an enormous difference to your pacing experience, so I would ask for details of these new parameters and work with a Boston representative until you find the correct parameter setting for you.

Lavender

by Heike - 2024-08-20 08:13:14

Thank you, Lavender, for your comment.

In the Netherlands I can't call Boston Scientific. Everything goes through the cardiologist. A technician from Boston Scientific was there to reprogram my Proponent a bit. She just said that the setting options are the same and therefore the Proponent should work exactly the same... but it doesn't.

For the answer from Gemita

by Heike - 2024-08-20 08:44:56

Thank you, Gemita, for the detailed answer.

I know very well the setting options of all the pacemakers I have had... the settings for each system were changed between 10 and 20 times, often with a technician from the company. But I also learned that these technicians only know their own systems to a limited extent. In my experience, Biotronik technicians in particular know the system very poorly. It would take too long to explain all of this now. In any case, I should not have had the Biotronik implanted in my groin. The Biotronik technician agreed to this and said that the CLS sensor can function perfectly normally at this point in the body.

A truly optimal setting was not possible with the Accolade either and this was not easy to achieve, but these settings were the best possible compromise. So I was supposed to get another Accolade, but then the Proponent was inserted, which I was not told about. The Proponent was implanted in the same pocket under the muscle as the Accolade, but it may be positioned a little differently than its previous one. I was told that it can take 4-6 weeks for the MV sensor (minute respiratory volume sensor) to function normally, as wound healing can inhibit the system a little. But after 6 weeks it was still a long way off. My heart health and general health did not change from one day to the next and all leads were attached as they should and are working perfectly. There are no differences with the predecessor either.

I had the reveal explanted in 2020 together with the Biotronik pacemaker.

The differences in the parameters of the L311 and L211 are fixed parameters that work in the background but are not programmable. Because I learned from the Biotronik that some parameters, even if they are not programmed to ON, can still affect the function of the sensors. Therefore, one of my thoughts is that these parameters for monitoring the sympathetic/parasympathetic autonomic balance affect the function of the sensors in the background, or that this affects the 'APP/ProAct' setting (this ensures that the pacemaker always stimulates above the patient's own rhythm). The company's technicians are often not aware of such software-related properties. As this is probably not really noticeable in most patients. As my underlying condition is inappropriate sinus tachycardia, which falls under dysautonomia, I can imagine that this sympathetic/parasympathetic parameter plays a role here.

Interesting thread

by crustyg - 2024-08-20 09:13:31

Hi: The exact orientation of the device has no direct influence on MV - it measures chest impedance from device can to the tip/ring of whichever lead is presently selected for use.  By contrast the single accelerometer is mounted in the device to respond to chest forward/backward movement, so even a small change in device orientation could have a big effect on the accelerometer's feed into RR for any given set of settings.  A different PM tie-down suture could also make MV relatively unreliable, and given the number of contributors here who have overly mobile devices where the anchor suture has failed this may be a factor for you.

Unless I'm missing something, you're very certain that RR is different between your two devices, but there's no detail beyond that.  Are you being overpaced or not reaching the required HR for the same physical activity?  Have you run out of sensitivity in the settings?

Autonomic activity: my EP-doc and I are still discussing this, as I now have episodes of HB when first becoming active.  My take on this is excessive parasympathetic drive (vagus increases AV refractory period) as my damaged atria don't produce enough ANP and my BP is too high.  With very few exceptions I never experience HB once I'm working hard, vascular peripheral resistance has dropped and sympathetic tone is predominant.  But for me, symp/parasymp can only affect AV-delay, since my device can pace RA and RV at whatever rate it chooses: in your case I'm not sure I see how symp/parasymp has any effect on your HR, *unless* your device is responding to changes in your AV-node behaviour.

This year the firmware in my L331 was updated (with no discernable difference to my RR): it's entirely possible that some 'hard-coded' sensitivity parameters are different between models from the same vendor, so that the same adjustable settings don't produce the same RR behaviour as before.  Having worked in closed-loop control systems I'm well aware of inter-device calibration issues.  There's no guarantee that BostonSci are using the same accelerometer chip on Accolade and Proponent and have tried to make the two models behave the same with software adjustments - apparently without success.

In the end, RR is just a software algorithm acting on feeds from a device (the accelerometer) and some very clever chest-impedance measurements combined with filtering software.  In your shoes I would be pushing my EP-doc hard about the decision to change device model.  Specific additional benefits?  Cheaper device (I think it is)?  Or something else?

Thanks Crustyg

by Heike - 2024-08-20 10:11:58

"The exact orientation of the device has no direct influence on MV - it measures chest impedance from device can to the tip/ring of whichever lead is presently selected for use."

This was my opinion too. If the MV sensor has been calibrated, then in my opinion it should work the same regardless of whether it is maybe positioned 1 cm differently in the pocket.

The one I can do is to ask the cardiologist whether the previous HSM was in a different position than the current one is. There is nothing about this in the protocol.

"By contrast the single accelerometer is mounted in the device to respond to chest forward/backward movement, so even a small change in device orientation could have a big effect on the accelerometer's feed into RR for any given set of settings.  A different PM tie-down suture could also make MV relatively unreliable, and given the number of contributors here who have overly mobile devices where the anchor suture has failed this may be a factor for you.
Unless I'm missing something, you're very certain that RR is different between your two devices, but there's no detail beyond that.  Are you being overpaced or not reaching the required HR for the same physical activity?  Have you run out of sensitivity in the settings?"

If that's the case, then everyone who gets a pacemaker replaced with the same system and the accelerometer is programmed would have to get a new fine tuning?
My pacemaker is under my pectoral muscle. For me, the biggest problem is in the 'lower' frequencies and when the accelerometer is not working either, because my upper body is then hardly moving. Then I get 'air hunger' very quickly. If, for example, I have to concentrate, stand up talking to someone (then I also have problems standing), driving in the car (concentration) etc. For this I need an aggressive setting of the MV sensor, which can then raise my pulse because the accelerometer does not detect any movement. In contrast, when my pulse goes up very quickly and high according to the accelerometer, then I get short of breath.

Now the MV sensor's 'Minute Ventilation Response Factor' has been increased from 12 to 14 and as a result the MV sensor now reacts much more aggressively. When I'm talking to other people and laughing or something, my pulse than can constantly changes between 80 (lower rate) and 120 (my upper rate is 170). But with this setting now I no longer have much problems when driving a car or when I'm sitting on the couch and I have to concentrate. But conversation and other things are still not as easy anymore, wich were also no problem anymore with the Accolade. The 2 setting options that are left now are very limited and a worse compromise than from the Accolade.

"Autonomic activity: my EP-doc and I are still discussing this, as I now have episodes of HB when first becoming active.  My take on this is excessive parasympathetic drive (vagus increases AV refractory period) as my damaged atria don't produce enough ANP and my BP is too high.  With very few exceptions I never experience HB once I'm working hard, vascular peripheral resistance has dropped and sympathetic tone is predominant.  But for me, symp/parasymp can only affect AV-delay, since my device can pace RA and RV at whatever rate it chooses: in your case I'm not sure I see how symp/parasymp has any effect on your HR, *unless* your device is responding to changes in your AV-node behaviour."

My atrium is severely damaged by several ablations: sinus node ablation, ablations in the area from the AV node to the HIS bundle and ablations of atrial tachycardias anywhere in the atrium. Therefore, new ablation is no longer possible and the AV conduction into the chamber no longer works. However, I have a retrograde return and very symptomatic junction arrhythmia which must be suppressed by the pacemaker and therefore the 'APP/ProAct' setting is active. This parameter also reacts differently than I I'm used to.

For me, the accelerometer feels like the only constant of the two pacemaker models.

retrograde conduction

by Gemita - 2024-08-20 10:58:48

Heike, as suspected, you have confirmed that you are still getting pacing induced arrhythmia (retrograde conduction) and that won’t be helping.  Until you get that sorted the finer adjustments of your settings will be difficult to achieve.  

I have a Medtronic pacemaker.  I also have atrial preference pacing.  I find it helpful in decreasing the number of my daily atrial arrhythmias:  sinus tachycardia, multi focal atrial tachycardia, Flutter, AF and lots of other stuff.  I have been extremely responsive to pacing and feel well with AAI pacing which is at 100% now, with minimum ventricular pacing.

I see that your ProACt algorithm reacts to premature atrial contractions  while the APP algorithm reacts to non-PAC atrial senses.  I do appreciate these algorithms are either ON or OFF, with no adjustment possible.  Does Boston have Rate Smoothing algorithms to help outpace irregular, pausing beats?  I believe Rate Smoothing can be adjusted.  Several members find it helpful.

I would focus on getting your retrograde conduction under firm control before you develop worsening symptoms if this is at all possible.  Do you know what settings they have adjusted to try to get this under control, like adjustment of PVARP or adjusting the sensitivity of the atrial lead so that sinus P waves are sensed, but not retrograde P waves?  Are you taking any meds?  Lots of questions to try to see where adjustments could be made.

Thanks Gemita!

by Heike - 2024-08-20 12:11:44

"Heike, as suspected, you have confirmed that you are still getting pacing induced arrhythmia (retrograde conduction) and that won’t be helping.  Until you get that sorted the finer adjustments of your settings will be difficult to achieve." 

That's exactly right. Unfortunately, I can't tolerate medication either. The fact that this is the case doesn't explain why the Proponent now works differently than the Accolade, although according to the Boston Scientific technician it should.

"I have a Medtronic pacemaker.  I also have atrial preference pacing.  I find it helpful in decreasing the number of my daily atrial arrhythmias:  sinus tachycardia, multi focal atrial tachycardia, Flutter, AF and lots of other stuff.  I have been extremely responsive to pacing and feel well with AAI pacing which is at 100% now, with minimum ventricular pacing."

I'm really happy to hear that it's working better for you. As is probably the case with most patients. In my case, the junction arrhythmia/escape rhythm causes the heart valves to close too early and my cardiac output then decreases, even when I am stimulated at 100%.

"I see that your ProACt algorithm reacts to premature atrial contractions  while the APP algorithm reacts to non-PAC atrial senses.  I do appreciate these algorithms are either ON or OFF, with no adjustment possible.  Does Boston have Rate Smoothing algorithms to help outpace irregular, pausing beats?"

Yes that That's right. These algorithms can only be programmed to ON or OFF and the rate smoothing increase is ignored at stimulation frequencies below the maximum APP/ProACt stimulation frequency (120 in my case). The rate smoothing is off for me and doesn't help in my case.

"I would focus on getting your retrograde conduction under firm control before you develop worsening symptoms if this is at all possible.  Do you know what settings they have adjusted to try to get this under control, like adjustment of PVARP or adjusting the sensitivity of the atrial lead so that sinus P waves are sensed, but not retrograde P waves?  Are you taking any meds?  Lots of questions to try to see where adjustments could be made."

I agree with you that you should focus as much as possible on the cause.
I don't take any medication because I can't tolerate it. My only hope is that a new drug is coming onto the market that can suppress the junction escape rhythm and which I can better tolerate. A new ablation is no longer an option, as my atrium is already full of scars from previous extensive ablations and would rather lead to a stand-still of the atrium, something that is also not desirable.
I no longer have sinus rhythm because I have had 2 sinus node ablations, so the junctional replacement rhythm functions. Because of all this, it is necessary that my atrium is stimulated 100%. In VVI, for example, I can no longer do anything.
With the Boston Scientific, I have regained more quality of life. This was not the case with Biotronik. Biotronik competed with the junction Escape rhythm. Even after optimizing the AV time via ultrasound, nothing helped.
PFARB is 240-280ms, VRP 170-250ms.

Email

by Lavender - 2024-08-20 15:52:07

I'm surprised you can't call the manufacturer. You would think you'd at least be able to email them. Here we get a booklet with contact info for Boston Sci and can call as needed. 

Email...

by Heike - 2024-08-21 13:23:39

Hello Lavender,

When I still had my first pacemaker from Medtronic, which was to be replaced by another system, I emailed Biotronik in Berlin asking whether the acceleration sensor works in the background or not when the CLS sensor is active, because the accelerometer was not allowed to be active in my case. Biotronik then sent me back to my cardiologist and they did not answer my question. At that time, no Biotronik was implanted in my heart center and so they had no idea but also the technician from Biotronik in the Netherlands had any idear. The technician told to my cardiologist that the accelerometer doesn't do anything when CLS is active ... although the accelerometer does work 20% in the background! It was only 3 years later, when a technician from Berlin came to the Netherlands to assess my settings more closely, that Biotronik NL's statement was contradicted. It was clear to me from the beginning, ever since I had the Biotronik implanted, that the accelerometer was working in the background, but everyone always denied this.

The Boston Accolade was adjusted a few times by a technician from Boston Sci, after which I had another question, but they also said that there was no direct contact between the company and the patients...

I will try emailing again, but I wonder whether it would be better to email Boston Sci in America or the people in the Netherlands. My fear is (as was the case with Biotronik) that the employees in the Netherlands do not know everything as well as those who developed the system.

Sheesh

by Lavender - 2024-08-22 20:01:21

Their device is in your body. I can see that there are limits to what they would discuss with nonmedical personnel, but they should be able to answer your questions. 

I called maybe three or four times in the three years since I have had the device. Every time they spoke with me and answered my questions. Once it was because I was having a colonoscopy and wanted to know if it was safe, another time it was because my voltage was turned up by the tech with cardiologist approval. I had more questions and they explained everything to me at Boston Sci. 

My body. I want to know what your device is doing in there. 🙃