Is respiratory rate sensor important?

I'm scheduled to get a pacemaker installed Thursday. They want to use a Medtronic PM with a motion sensor but not a respiratory rate sensor. I'd like to be able to ride my bicycle up steep hills and also do some backpacking. What is your experience exercising with the motion sensor only? I have sinus bradycardia with 2nd degree AV block ( Mobitz II ). Thanks.

8 Comments

Pacemaker Rate Response

by SMITTY - 2010-05-04 08:05:20

Hello Gstair,

Welcometothe Pacemaker Club.

I think you have nothing to worry about. Your pacemaker will have a rate response feature and it will increase your heart rate based on several different determinations. One is physical activity, such as walking, running or riding a bicycle. We have even had members tell us of having their rate response kick in and increase their heart rate when they were riding over a rough road. Physical activity is not the only thing that can activate the rate response. Increase in body temperature, and even stress will do it. While I can understand temperature and physical activity causing the rate response to increase the heart rate, the stress part is a mystery to me.

So I say get your pacemaker fully expecting it to keep your heart rate at what ever is needed to accommodate your activity. I will add this to avoid thinking the RR is not working if you think your heart rate should be higher for some activity. The standard setting for the RR is 220 minus your age times 90% (220 - age X .9). This setting can be altered by your doctor if he thinks it is in your best interest.

As for your concern about being told that your PM would not have a respiratory rate sensor, I would discount that. I can't imagine anyone ever having an increase in respiration without any increase in physical activity. Again, the RR will increase and your heart rate as needed, and if it doesn't then changes can be made in the RR settings to give you what you need.

Frankly, I would not be surprised if the person you were talking too simply did not know enough about the rate response feature to tell you how it would or would not work. But if you need help, give us the model number and I'll bet we can get the needed information from Medtronic for you.

Good luck,

Smitty

Rate response is complicated

by golden_snitch - 2010-05-05 02:05:30

Hey,

that's good! I hope it's work out fine for you.

@Smitty: No, not every pacer responds to respiratory rate, in order to do that it needs a minute ventilation sensor. Thing is, for example when you are riding your bike, the upper part of your body is not moving that much which is the reason why a simple accelerometer sometimes doesn't respond appropriatly. But the minute ventilation changes for sure when you are riding your bike, and that's what a pacer with two sensors can detect and then it increases the rate.

Also a pacers rate response doesn't react to an increase in body temperature. With a working sinus node your heart rate will increase when you have a fever, but if your sinus node is not functioning and the pacer has to take over, it won't. It doesn't have a sensor to detect changes in body temperature. There have, as far as I know, been trials with such sensors but the pacer models that are on the market now don't have it.

Stress only activates the rate response sensor in Biotronik's pacer models with CLS (closed loop stimulation) which is based on measuring the heart's contractility; no other manufacturer has CLS. Doesn't work well, however, when you are on betablockers or any other anti-arrhythmic drugs that make the heart less sensitive to adrenaline. The heart's contractility changes, the more adrenaline is produced, and that's what CLS measures. Pacers with CLS need a ventricular lead in order to measure contractility, and the highest rate CLS can pace you is 165bpm - not that much.

You see, this whole rate response thing is much more complicated than you think, and it's one of the aspects that are different in each manufacturer.

Best wishes
Inga

I like two sensors better

by golden_snitch - 2010-05-05 03:05:50

Hey,

all of the cardios/EPs I have ever met told me, with regards to pacers, that young and active people need a dual-sensor rate response (if they need the rate response, most heart block patients don't). Accelerometre is not enough, that's what I have been told. So I have always had a combination of accelerometer and minute ventilation. The accelerometer is the one that responds quickly but doesn't keep the rate up for long; the minute ventilation sensor reacts not that fast but it makes sure you've got a steady and appropriate rate when for example running for miles etc.

The good thing about two sensors is that you can have both switched on or, if you feel like you don't need both, you can have the minute ventilation turned off. When you have only one sensor and find out that this doesn't work well for you, there is nothing you can do about it.

Now, Medtronic used to have one pacer that has accelerometer plus minute ventilation, the Kappa 400 series. It's an old series, I got mine in 1999. The newer Medtronic series do not have both sensors, they have an accelerometer only. My new pacer is a Sorin Group "Reply" and it features both sensors. It works perfectly for me. Boston Scientific also has a model with two sensors, I think it's the "Altrua", but I know only one patient who has it and she's not happy with the rate response; might be a setting problem, though.

I'm a big fan of dual-sensor rate response. I have once had the minute ventilation switched off but with the accelerometer only I didn't do well at all. I have no sinus node so I'm paced almost 100% in the atriums and am highly dependent on a good rate response.

Best wishes
Inga

I'm getting my way

by gstair - 2010-05-05 12:05:50

After talking to the nurse at the heart hospital, they agreed to give me the Boston Scientific model with the respiratory rate sensor. They work with the three major manufacturers, but the doctor prefers to work with Medtronic.
I'm going to have this thing for 7 to 10 years, so I want as much flexibility as possible.
So, as of tomorrow, I will be a legitimate member of this group.

Yes, get your way

by ChicagoKim - 2010-05-06 09:05:33

I agree with Snitch and have heard the same thing. I am young(ish) :) and active and I have the Boston Scientific with dual sensing. I have a friend in her 20s that had her PM put in at Cleveland, and her EPs told her the same thing and gave her the Boston Scientific dual sensing PM as well.

st judes

by Hot Heart - 2010-05-07 10:05:53

love my rr on, feel like a different person. Almost immediately went from feeling like an unfit old lady to a fit filly! lol

My pacemaker is in

by gstair - 2010-05-08 11:05:20

I was blown away by the competence and caring of the medical staff and I am extremely grateful for the fine health care we enjoy. I had very little pain afterward, just a small ache and the only pain medication I took was at bed time. I'm feeling much more robust now and didn't realize how much I was affected by the low heart rate. Now I feel I have to do something worthwhile to compensate for what I've been given.

Wrong pacemaker - a caution.

by Old_Mainer - 2020-12-03 23:40:30

I didn't know enough to question my initial pacemaker choice.  I had it placed at age 77.  It has only accelerometer pacing and it drove me nuts - I am a swimmer (8000 miles in 50 years) and now also a sculler - neither triggers the accelerometer appropriately.  I drastically changed my drug strategy and had it all pacemaker functions turned off except minimum rate which kicks in at night.  When my afib gets bad enough again I will agitate for a dual sensor system so I have the choice of acceleration or minute volume.

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