Rate Response

Good day everyone. This is my first post, joining just moments ago. I hope you are all doing well.
I had a Biotronic Evia SR- T put in on Feb 3. My symptoms were a resting hr of 40 and unable to get above 110 while exercising. An EKG showed a bad 'P-wave', so I had the 1-lead pm put in the same day.
My problem involves an erratic response to exercise (jogging); I.e. sometimes my hr stops climbing at 110-120; same course another day, hr goes to 180. Hr sometimes decreases when I exert more, and sometimes it increases when I slow to a walk. My breathing varies with hr, I.e. really puffing when running and hr stays low, and very comfortable when hr increases like I think it should.
I had a consult and adjustment last week, but it did not help. I do not know the entire meaning, but I understood they adjusted the CLS but had the accelerometers deactivated? Could this be a hardware or a software problem? My pm is active 94% of the time supposedly. Is it possible to simply have the pm increase hr to near max while exercising and decrease when activity slows?
I am sorry for the long post - I am just frustrated. Thank you for taking the time to read this.

4 Comments

Cardiac contractility

by golden_snitch - 2014-06-07 01:06:07

Hi!

An atrial pacemaker can only be in an atrial mode, so AAI or AAIR. According to the manual, there is no AAI-CLS, only AAIR which would mean that the accelerometer is on. Makes sense because, I forgot this in my first comment, CLS measures cardiac contractility, and that needs to be measured in the ventricle, not atrium.

It makes little sense giving someone with sinus brady and chronotopic incompetence a single-lead, atrial Evia pacemaker. Patients with this diagnosis need a good rate response sensor. CLS can theoretically not be activated in your pacemaker, so you are left with accelerometer only. Biotronik's accelerometer is not better than other manufacturer's accelerometer; and it is definitely inferior to a pacemaker with accelerometer + minute ventilation sensor (this combination works in AAIR). Accelerometers have limitations, for instance they do not react well/at all when you ride your bike, and they fail to increase the rate when you run for rather long distances.

Yes, if your own rate exceeds the upper CLS rate of 160, it can of course take over. But I really don't think you are in CLS, and since you said you could not bring your heart rate above 110 when exercising BEFORE you got the pacemaker, it would be a surprise, if it now gets up to 180. I think the 180 is from the accelerometer sensor.

Inga

Biotronik

by NMsnow - 2014-06-07 01:06:54

Thank you for the fast response. A few more details - I have a single lead atrial. I will be calling on Monday to see why I am running CLS for this configuration. My limited understanding is when the pm maxes, 160 for me, it will stop its signals and let the body take over and go faster if that's what it is wanting to do.
Also, during my adjustment, I asked if I should have the min hr boosted from 60 to 70 or 75 , since I was feeling light headed when getting up from sitting. They did not raise the hr, but whatever they did seems to have helped that. I am going to emphasize I just need some kind of program to respond to movement/exercise.
Thanks again for the response.
Gene

Biotronik

by NMsnow - 2014-06-07 01:06:59

Thank you for the fast response. A few more details - I have a single lead atrial. I will be calling on Monday to see why I am running CLS for this configuration. My limited understanding is when the pm maxes, 160 for me, it will stop its signals and let the body take over and go faster if that's what it is wanting to do.
Also, during my adjustment, I asked if I should have the min hr boosted from 60 to 70 or 75 , since I was feeling light headed when getting up from sitting. They did not raise the hr, but whatever they did seems to have helped that. I am going to emphasize I just need some kind of program to respond to movement/exercise.
Thanks again for the response.
Gene

Biotronik Evia

by golden_snitch - 2014-06-07 12:06:47

Hey there!

I have a Biotronik Evia DR-T since January (not my first pacemaker, though). I'm paced 100% in the atria and ventricles, so I need the rate response virtually for every move I make. Here's my experience with this sensor so far:

The CLS can be tricky. First of all, according to the manual it's either CLS or accelerometer, you cannot have both switched on. This is also reflected in the mode your pacemaker is in: If CLS is activated, the mode is either DDD-CLS or VVI-CLS. If you have the accelerometer activated, it's DDDR, AAIR, VVIR and so on. However, I'm in DDD-CLS mode, but the report also shows accelerometer settings which is a bit confusing. Will be seeing a Biotronik tech on June 26th, and am going to ask him about this. What's also interesting is that you cannot have AAI-CLS, but only VVI-CLS. From what you wrote, my guess was that you have sinus bradycardia (leading to a junctional escape rhythm with a negative p-wave) and chronotopic imcompetence. And that you got a single-lead atrial pacemaker for that. But, if you do have the CLS on, then you must have a ventricular lead only - at least according to the Evia manual. Sorry, but this is really confusing.

The max. rate the CLS sensor can do is 160. So, I wonder where your 180bpm come from. Can either be your own rhythm - need not be sinus rhythm, could be some other atrial rhythm - or it is the accelerometer, because that can go higher than the CLS sensor.

The problem I had with my CLS sensor in the beginning was that I got a racing heart beat with minimal exertion, even when I just walked to the kitchen or when I tied my shoe laces. It was awful. But this settled down as soon as I started going for long walks regularly (3-4 times per week, at least 45 minutes). The sensor learned and automatically adjusted. I could feel the difference from day to day. Had I been walking with 160bpm the first two or three days, this rate slowly decreased, bit by bit, and now I'm walking with 80-100bpm. Same with jogging: 160bpm in the beginning, but now that I started to run 30 minutes straight without pausing, I'm down to around 130bpm. For jogging, the sensor took a little longer to learn, but eventually it did adjust.

Maybe your problem isn't the CLS sensor, because a rate of 180 definitely cannot be caused by this sensor. The accelerometer can be fine tuned: You can program how fast the rate increases and decreases; you can change the sensor threshold (nominally "medium", but very low, low, high and very high is also possible) to make the rate response more/less aggressive; the sensor gain can also be adjusted (higher if the rate response is insufficient, lower if it's too fast).

Either way, fine tuning a rate response sensor, no matter which one, often takes some time and multiple adjustments. So far you seem to have had only one adjustment. Hang in there and keep asking for optimization of your settings until you feel better!

Best wishes

Inga

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