Rate response of pacing feature stops working after 50 or so minutes.

Heart Rate drop

by Gemita - 2022-01-24 08:18:36

John,

Firstly, welcome to the Club.   I am not a cyclist, nor do I have a Boston Scientific Proponent L211, but I hope members who are cyclists and have Boston Scientific can give you a few ideas of what might be going on?  

Just a thought, I wonder whether it would be worth asking your pacemaker technicians if they could consider having a representative from Boston Scientific actually present at the time of your next appointment to personally carry out a few checks on all your settings while you are having perhaps a treadmill test?   They might be able to see first hand what happens when your heart rate hits a certain level, after a certain time period, triggering a heart rate drop.  I know with Medtronic there is a Rate Drop Response setting that can be oversensitive and may need fine tuning.  We also have a Mode Switch setting which prevents tracking of a fast atrial tachyarrhythmia, since I see you have Atrial Fibrillation too.  Is it possible that your pacemaker is set up to control any high heart rates?  

Most members here find treadmill testing invaluable to get to the bottom of their problems and to fine tune their settings to suit them, although I appreciate yours is a specific problem that occurs during cycling after a period of time.  I note you have just received 4 day monitoring of your heart when you had three rides and when the Pacing feature was confirmed to have turned itself off.  Keep up the pressure John and I hope you get some answers.  Good luck in the World Over 80’s Gran Fondo Cycling Championships.  I am sure you will do well.  Both my husband and I have pacemakers and live in the UK too.

Not enough information to assist

by crustyg - 2022-01-24 10:34:37

Proponent is one of several PMs from Boston Sci that supports Minute Ventilation as well as the more common accelerometer feed into Rate Response.

If you're a road cyclist, it's very likely that most of the RR that you rely on when cycling comes from MV.  Getting MV to work is quite difficult (for the vendor) and uses a very small signal that has to be teased apart from a lot of electrical noise, so Boston Sci provide a Signal Artifact Monitor to prevent noise feeding into RR.  If this monitor detects enough interference, the net result is that MV stops working, either for a few hours, or permanently (until the PM is reset).

For some reason Boston Sci don't raise an Alarm event about SAM activation so a) it doesn't transmit through Latitude remote monitoring and b) it's easy to miss during an in-person session with EP-techs (it's just happened to me).

However, if it's happened more than once I would be surprised if no-one had spotted it, so what you are describing is starting to sound like a bug.  But you haven't provided enough detail about pacing, MV-vector, what was found in your in-person testing etc.

But has anyone else come across something like this?  Yes, I have.

The MV signal is very sensitive to moving magnetic fields, even from something like the flywheel of a static bike.  I've proved this to my own satisfaction in a number of tests, static bikes etc.  However, and more importantly, I've had a number of episodes where MV has ceased to feed into RR, *usually* when I've been drifting in a slowish peloton so that my HR is fluctuating above and below 90BPM.  The MV signal that feeds into RR is actually a delta between short-term MV and a long-term baseline, and with my settings the longterm baseline locks at 90BPM (actually the lock expires at 4hour and then releases no matter what my needs are).  My experience is that sometimes under these conditions MV ceases to feed into RR and then riding becomes very difficult.  I have found that slowing down (or even having a drink stop) so that HR stays well below 90BPM for 10min plus (I haven't timed it) then allows MV to restart and my HR is raised when I need it.

I've provided all this to Boston Sci (through my EP-doc - Boston Sci won't deal directly with patients, in line with other PM vendors) but they flatly refuse to accept that there might be a software bug in there.

Thank you

by jwmj@gmx.com - 2022-01-28 18:38:22

Many thanks Genita and crustyg to take time out to respond to my post,    I will discuss your ideas with my Pacing Consultant,

I also think there is a fault with my Pacemaker but according to Boston Scientific it is working as expected.

A funny day today, same start as normal with HR rate up to 130, then 2 hours with it arouind 95 and near the end of the ride for about 5 minutes my Heart Rate started increasing to the 120's,  Did not last long but it sure makes a difference when you are riding,  Regards John

May be having a similar issue-different sport

by JWren - 2022-02-07 21:32:05

I am primarily a swimmer. 72 years old. I initially got a Medtronic device 3+ years ago.  It was not very good for swimming.  To make a long story short, I chacnged EPs and we thought a BS with MV woud be more effective.  I broke a wire in April of '21.  Since he had to go in a repair it, we agreed to change the device and I was hopeful.  I saw improvements for hiking and biking right away.  Runinng was ok.  Swimming, however, ranges from sort of ok to awful.  I am 5-10% slower than I was with the Medtronic.  I've had four adjustments and my latest advice is that we may just have to live with it.  What struck me about John's experience is that he is quite sure that the device behaves well at times and then shuts down.  I have some days in the pool that are very poor with no apparent reason.  It's very frustrating.

Me Too

by Mike417 - 2022-02-17 17:00:14

I have an Accolade with MV.  And I have had a similar issue, but with walking.  Iit is about the same time, i.e. 50 min.  I documented it with my polar H10 for the EP team.  They then scheduled me for a longish, 40 min., treadmill test.  They also monitored my SPO2.  The BS tech was there also to record and analyze the data, including how the MV was working.  At 35 min, my pacemaker cut out with a HR of 132 (uper limit 150), down to 90 bpm.  Everyone was perplexed, and they had never seen this, but then they sent it off to the BS Techs.

After a week  one of the BS physiology techs contacted us;t this is a built-in safety feature, and they get calls about this a few times a year. He explained that HR and breathing are described by an algorythm in animals, and they use this curve with the electricval signal from the MV to increase and decrease the HR.  This happens to me around 115-120 bpm, up till then the HR is guided by the accelerometers.

If your breathing is not in concordence with your HR it is designed to cut back, since it could be electrical or magnetic interference.  It resets after 30-60 min.  If I get tired (I am walking about 4 mph) and my breathing becomes erratic, guess what!  If I cool down too rapidly, short of breath, and etc., my PM cuts out.  So I have started to do rhtymic breathing now when I walk.  When I do this I do not experience the PM cutting out.

The local rep, and the EP team (at a major research univ. hospital0 did not know this!  I still have a lot of questions, but I have to give it a rest.

JWren, I have a similar story to yours.  I started out on a Medtronic azure, and could not walk up hills or go hiking.  I had my EP swith out to a BS PM, but feel slower.  I think the Medtronic was programed with an aggressive RR to make up for having a single accellerometer.

So that is my lesson, do paced breathing.

Mike