Sticky CLS (Closed Loop Stimulation)

"Sticky CLS"

by AgentX86 - 2021-11-05 13:35:47

Could this be PMT (Pacmaker Mediated Tachycardia)?  My guess is the CLS is getting confused and pushing the PM into PMT. I wonder if they've tried turning off CLS?

CLS issues

by Jerry10 - 2021-11-05 15:44:26

Hi Gemita and Desmodrome...

My experience might be relevant.  I had exactly this issue after my implant a month ago.  (Biotronik Edora 8)  May I suggest the following?

To debug the issue, the first step is to TURN OFF CLS, and if practical, do NOT replace it with the motion-sensor rate response algorithm. This should fix your pacing at your base rate, i.e. you're stuck in one gear.  (I believe this is DDD mode.) Anything above your base rate is "you", not the PM. 

See if you still have the problem ... I did! So we concluded it wasn't the PM at all. 

If you don't have the problem with all adaptive pacing off, then turn on the motion-activated rate response feature. (I believe this is DDDR mode.) If you still don't have the problem, then turn CLS on, and see if the problem returns. (I believe this is DDD-CLS mode.) If not, you're fixed! :)  If so, it's definitely something related to CLS.

Note that the Resting Rate Control feature is normally turned on, and the default value is +20BPM. What this does is limit the CLS to a 20-BPM increase when no motion is detected. If motion is detected, then CLS is limited only by it's max programmed rate. In other words, CLS with Resting Rate Control involves both motion and CLS.

You didn't mention this issue, but note that the Resting Rate Control with CLS is incompatible with stationary exercise - like a stationary bike. You will experience at most a 20 BPM increase in rate, which is very little and insufficient for a workout.

Another suggestion - turn off the darn automatic Sensor Gain. This will ratchet up (or down) the sensitivity of the CLS algorithm weekly, based on how much it thinks you are exercising. Set it to some fixed value, then adjust it manually as needed. 

Another note: Unless you have changed the defaults, you will still briefly experience an increase in rate at 12:30AM each night, for a minute or two at most. This is the PM testing to see how little power it needs to deliver to get your atrium, and separately your ventricle, to beat. This is called "autocapture". You can turn this off, change the time, etc., but it's a valuable feature as it's purpose is to maximize battery life. 

As a computer guy, and a skeptical one at that, may I say that it's unlikely that the device is actually malfunctioning. More likely CLS isn't sensing your physiological changes correctly - you may simply not exhibit the change in impedance under exertion they are looking for, or more likely, you are exhibiting changes in impedance with no exertion, which will cause CLS to run up your rate - which is what you are seeing. Lots of things could cause your impedance to change, including mental stress. So if you're a sensitive soul lying awake at night and think of something unpleasant, this can cause CLS to increase your rate.  In other words, your body may not be typical and CLS may not work for you.

But motion rate response should work for anyone. Sit still and you're at base rate; jump around and it goes up. If CLS isn't a match for you, try the regular rate response - it's rock solid as far as I can tell.

I hope this information is helpful, please let me know if I can try to answer any other questions, and please - post updates so others (including me) can learn from your experience!

Jerry

Sticky CLS (Closed Loop Stimulation)

by Desmodrome - 2021-11-09 18:26:52

Gemita, AgentX86 and Jerry10 thank you for helping me and your comments! :-)

@AgentX86: I have not tried CLS off (yet). I'm not a doctor (electronic/computer educated) and english is not my native language, so I struggle a lot to just undestand the explanations of PMT. Need more time to study/read/understand what PMT is and how it occours. But from the manual for my device (Biotronik Riacor 7 HF - T QP)  I see that it has PMT protection, that is the detection/termination which default/standard setting is ON. So let us hope, or pehops not hope, that this feature is enabled. ;-) 

Jerry10: I do agree with you that if you do not know what the problem is or where to start, the most common practice in my world dealing with electronics/computers is to eliminate causes by starting frrom scratch or a known status which is confirmed. But I'm told by the specialists that when you combine eletronics and algorythm with a unique human body with "male functions" its not always that simple. But basic facts and common sence combined with logic thinking mostly solves any issue ;-). As for your recomendation of  "turn off the darn automatic Sensor Gain", the manual says that the option AUTO Sensor gain, is only available when the timing is rate adaption via accelrometer. When the rate adaption is via CLS the amount of available parameters are in fact quite few, and Sensor Gain AUTO is not an option as far as I can read. The resting rate control it is set to +10bpm on my ICD, but one could suspect this functinality does not work as intended, since it spikes for 2-3 minutes to +/- 100bpm, which is way above resting rate 60bpm +10bpm when I turn from side to side in bed. As far as I understand the acclerometer is only used in resting rate control to detect body movement, but plays no part in the algorythm for rate control. Wether or not the sudden raise in rate is caused by "sticky CLS" as Biotronik in Germany has concluded or it is my body that in some cases causes the impedance to rapid change or it is my heart that goes in to a "flutter state" is still a mysteria to be solved! :-)  Best Regards Desmodrome