rate response

Can anyone explain how rate response works?  I don't think my PM is set at a high enough level and I get so short of breath I have to stop walking until I recover enough to continue.    Still having shortness of breath almost two years later. Medtronic PM 12/17 for 2:1 AV block, followed by PE 3 days later. 

Have an appointment with EP in a couple of weeks and have asked for records of all my PM checks so I can be prepared to ask questions.  

If anyone has strategies for dealing with EPs, let me know. 

Thanks 

vjer


4 Comments

How it works...

by crustyg - 2019-09-09 17:06:27

Rate responsive PMs have an accelerometer in them - the same technology as in a smart-phone that enables it to work out which way is up.  This provides some form of movement signal.  It can normally detect movement in all three dimensions.

Your PM is a computer running software, with a pulse generator that drives your heart.  The software sees the 'movement' signal from the accelerometer and feeds it into a software routine, the rate response algorithm.

Pretty much all modern PMs will have a lower threshold before they treat the movement signal as vigorous enough to mean 'patient is moving'.  They may also have a time delay - 'ok, patient is not just adjusting position of the Lazy-Boy'.  Once these two thresholds have been met, the software will then apply a response factor to the movement and feed the resulting value into a rate increase algorithm - 'patient is moving, so is assumed to need a greater heart output', which for most PM patients means a greater heart rate (HR) - the pacemaker driver increases the pacing rate.

So the PM increases your HR.  There will be some maximum HR that the rate response will be permitted to drive you to, there will be a factor about how long after you stop moving before your HR is allowed to start reducing and at what speed (bpm per minute) so that your blood pressure doesn't suddenly fall at the top of the stairs.

Some PMs will be set to be less sensitive at night - 'sleep mode', and some have an additional sensor which detects breathing - both rate and depth of each breath, and adds that to the rate response algorithm.

Some patients have their response factor set to maximum with minimum delay - if you dance seriously, you go from zero movement to maximum requirements in a couple of seconds, so you want HR increase to start ASAP and be rapid.  Others might want a less vigorous response.

Does that make sense?

Strategies

by crustyg - 2019-09-09 17:19:50

Listen carefully to what they say and if it's too dumbed-down, ask for more detailed information.  Read, listen, ask questions in places like this, so that your questions are more and more detailed, and soon your EP will look at you with new eyes, and realise that you *understand* what's going on, how things can be adjusted and what the implications might be.  Prepare a list of questions before each visit/PM interrogation, take a thumb-drive to the EP sessions and ask for a copy of *all* of the data.  If the EP tech or nurse won't provide it, make sure you EP doc has told them that they *will* give you the data.  Even if you don't feel able to understand it all right now, as time goes by you will be able to discern patterns, appreciate what's changed (pacing voltages, thresholds) and what they have changed in your PM and why.  It's a lot easier to negotiate 'please increase my accelerometer response factor from 8 to 11' than to ask 'please make it more sensitive to movement'.

Get hold of the reference manual for your PM, read it, and then ask questions about the stuff that you're interested in.  Here is a good start...

All good EP docs will become more willing to share and provide more information once they believe and accept that you understand the issues, can cope with the uncertainties (there are no exact answers to a number of questions in heart rhythm management and big differences between EP docs in different countries) and are motivated through a desire to participate in your management - after all, it's your body, your heart, your PM and ultimately, your life.

If they don't respond in a positive way, then you change them - see above!

Hope that helps.  Questions are how we test our understanding and the only foolish questions are the ones that we never ask.  I'm well past being embarrassed at asking a question for which there's a simple answer that perhaps I should have known.  I forget things, and I've never known everything, nor will I ever.  We don't have time to hesitate from embarassment, and I've learned to have no shame - at least not where my health is concerned.

Listen to Crystig!

by Gotrhythm - 2019-09-09 18:21:35

His advice is solid gold.

About rate response. There isn't some formula that lets the doctor look at your chart and compute what your rare response setting should be. It's pure guess work, and whether it's right sometimes depends not so much on what you need, as how you like to feel.

That means you need to talk to the EP and the team. As Crustiyg says, the more you know the better you will be at speaking their language. They don't know if RR is "right" unless you tell them. It was when I found an EP who listened to what I wanted my pacemaker to enable me to do, dance, that I finallly got the more sensitive RR that I needed.

Do what Crustyg says.

Medtronic changes

by Theknotguy - 2019-09-09 23:16:32

I've had a Medtronic pacemaker for six years.  I also have two programs running for afib, APP (Atrial Preference Pacing) and Minerva.  I've gotten along fine for six years and started having problems this summer while walking and mowing the lawn.  

Mostly what would happen is that I would get a pain in my left shoulder, then run out of air.  I'd also get dizzy when if I would stand up quickly.  

I mentioned this to my EP and he sent me for a series of tests.  His first thought was that I had a bad heart valve.  Another test was a treadmill stress test. They both came back negative.  So he sent me in for a TEE.  However the cardiologist who was going to administer the TEE wanted to take another look at my heart via an ultrasound.  We were in the procedure room where they were going to perform the TEE and he was doing the ultrasound there.  He saw something on the ultrasound and said, "Cancel the TEE, we just need to adjust the pacemaker."  I, of course, was happy to hear that.  

They made two adjustments to my Medtronic pacemaker.  One was to adjust the rate response.  There are five settings and I was on the first and lowest setting.  The tech moved my rate response up one level.  He indicated if you make too much of a change it can also cause problems.  

The second change was to my Minerva program.  They brought in a manufacturer's rep from Medtronic and he brought up some screens I've never seen before.  He was able to make a change to the Minerva program - it was at the lowest setting too.  The changes made a major difference and I started  feeling a lot better.  I don't understand the technical details of the changes done to my Minerva program but they did help.  

I don't know if this will specifically help you or not because not everyone has the Minerva program on their Medtronic pacemaker and you may not need it, but at least you know there are some changes that can be made.  
 

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