Rate Response and UPPER LIMIT Rate of PM

Dear All,

I have a Double Chamber pacemaker since November 2005 (though I have been on pacemakers for the past 16 years), with rate responese function with limits set as 60-120. The rate response function was switched off by my doctor as my atrium can set rates on its own (Has always been). I am 38, located in New Delhi.
Now I was noticing over the past one year that when I climb steep slopes, say on hills or on the great Wall which is really steep, I was having real problem in breathing and my heart goes thump thump at an incredible rate. I have a general slight breathlessness problem, but it is nothing major. I have managed pretty well for the past 16 years with normal activities. My angio done last year was normal.

Anyway I went to my cardio today, he found through the PM test that my upper rate does go as high as 160 which my PM cannot sense (since upper limit is at 120). So now he has first turned the rate response on as he thinks my heart cannot beat enough at higher levels. Second, he has increased upper limit to 140 though apparently the medtronic guys here told him 'over 130 is not recommended'.
He has warned me against certain things. apparently with rate response and upper limit at 140, sometimes even with sitting in a shaking car (say) the PM may think my activity level is high, and beat at 140 which will be uncomfortable etc. Also if the PM cannot pace enough , it will start pacing at half the rate, so when I need 160, it will give me 80, not even 120! However, my cardio has advised me against avoiding strenuous activity (which I in any case hardly undertake so much, I hardly jog or do physical exercises) saying 'pursue a normal lifestyle'.

Question to you all: 1) do you think this will work? 2) Is 140 abnormally high for the upper limit to be set at? 3) How high do your heart rates normally go? 4) What should I expect and prepare for? 5) I have a hypothesis that with age, my heart's ability to go up (rate wise) for strenuous activities is coming down while its ability to generate 60 is coming down too. So now it seems i am on the PM 97% of the time (i.e. my heart rate is below 60 57% of the time, last year it was 75%. What do you think of that?
Sorry for such a huge message. But I really need information. Especially to Question 4. I am pretty normal and healthy generally and do not have much problem with my heart, PM otherwise. My echo is clear.
Thanks a lot (at least for reading through this!!! )
Ranjasg

4 Comments

me too

by maestro - 2007-07-20 02:07:20

I have the same brand PM you do, and I too have become light headed, winded when exercising vigorously. Actually, I was running from something, not a usual occurrence.

I asked my doctor about the max heart rate for the ventrical. He said the way to discover whether the setting was appropriately high enough was to change the upper limit and observe.

Frankly, my inclination is to trust the Medtronic experts, assuming you are assisted by a senior person. You can also phone the Medtronic help line to speak with their Electrical Engineer (assuming you are technical).

I had two cardiac surgeons who totally disagreed with the Medtronic people. They both installed settings which were insane, and not intended by the manufacturer. I am so glad I trusted the Medtronic people.

Also, you can consult the Medtronic Programming Manuals online. Great resource.

Heart Function

by SMITTY - 2007-07-20 11:07:01

I have some of the same symptoms you describe and my doctor calls my problem exercise induced arrhythmia. The reason for this is an increase in the level of adrenaline that accompanies exercise. I was told further that the premature atrial contractions and palpations are not considered serious, but if they are painful or uncomfortable, I should stop doing whatever is causing them.

As for the list of questions in your last paragraph, it sounds like you may be trying to rationalize your heart’s function as something mechanical so that you can apply a mathematical formula to get an explanation. In my opinion that is the wrong approach. The heart is a living organ and as such its actions are not necessarily exactly repetitive. The beats may be similar and they may fall within a range that allows them to be called normal as evidenced by various tests. But, in reality our heart function changes from beat to beat, depending on its perception of what our body needs at that moment.

My suggestion is take your list of questions to your doctor.

Good luck,

Smitty

Thanks and more on rate response?

by ranjasg - 2007-07-21 03:07:55

Dear Smitty and maestro,
Thanks a lot for your response. So I guess many people have the same problem like us, at higher level of activity.
Yes Smitty, you are right, I am probably trying to reach some formula. I agree with you that the heart really cannot be categorised like that but at the same time, some broad parametres should be applicable isn't it? Otherwise how will even a device like the PM function? There must be some broad guidelines, and then of course some part of the heart's function is random and specific to each individual, as you say. I am trying to understand what at least the broad guidelines may be.

Maestro, good idea to set upper limits at different rates and observe. I think that is what my doctor is trying to do. He has asked me let him know after a week how I am. Unfortunately here in India, the medtronic staff are pretty untrained, not as efficient as they are probably in the US and other developed countries. I have asked them many things in the past and they almost consistently get it wrong. I had an automatic self check set on my new PM, and it was giving out these 3 beats every 3 hours (which I could feel as I have unipolar leads), I and my doctor asked them and they categorically said it was not possible, and my PM did not have self check. But I stuck to my stand and My doctor then insisted they come and check it out thoroughly, and yes it was a lead impedance test set every 3 hours.
Also in India, there is (thankfully) a lifetime warranty on the PM, which means it is automatically replaced by the company over my lifetime ( I just pay for it once, isnt that great?). So it is in the interest of the company to keep upper rates low as it means less usgae of the PM and its longer life. I am not saying they recommend limiting it to 130 just for that, but one cant eliminate that possibilty. Thankfully my doctor is very good, and all the doctors there seemed to agree with him. Still, I am a bit apprehensive about setting it at 140 so was looking for info on whether it is generally set that high etc especially in other countries where there is no such obligation on the company to replace the PM.. I will check out the Medtronic website too, as you suggested.

I have read a lot of messages here earlier about the rate response and its problems. But cant find those now. Wanted to know what to be prepared for etc. Also that upper rate thing is bothering me a bit as I said. That thing of rate dropping down to half of required is something I have read about here. If anyone has any knowledge of that phenomenon, please do write in!

Thanks a lot to both of you, reading my marathon messages cant be easy!!! And good to know (not in a perverse way, I hope!) this thing (breathing difficulty at higher level of activity) happens to many people, even with a PM.
Ranjasg

My upper limit

by rosep - 2007-07-25 04:07:40

Hi Ranjasg,

I have had my dual chamber pm since March starting with an upper limit of 120. When I went back to exercise I found within a minute I was extremely breathless etc. Went back to clinic and was reset at 140 - this let me exercise for about 2 minutes before gettng breathless! So back to clinic. I met a new technician who was very good, asked for lots of info about my lifestyle and was happy to reset my upper limit to 185 as during exercise such as running or tennis my heat rate can run between 150-16, maybe higher. He explained that pacemakers come with factory settings and we need to keep tweeking them to find what works for us. Upto now I have had no problems with the new setting and I can exercise very comfortably now. I don't know too much about the technical side of it all and what effects it could have on battery life etc - the main thing is I feel fine! Hope you get yours sorted out to suit you too. Rosep

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