60/130 rate, what does it really mean?

I read somewhere from previous posts that the PM does not LOWER your heart rate, it only increases it. So, what does a rate setting 60/130 really mean? Can someone take me back to the basics and really explain what the PM does when these numbers are set? I thought I understood what these settings mean, but I'm more confused about it the more I think about it.
That's why I need to go back to the basics and understanding it more thoroughly so that I can communicate better with the PM tech and EP on this Friday for my check up. I thank you for any comments.

10 Comments

PM Settings

by SMITTY - 2013-07-21 05:07:11

Your PM has two settings (actually it has many more than two but to answer your question I will talk about the two we most often hear discussed.

The PM can only increase heart rates So the PM has a low setting and a high setting. The PM monitors those set points 24/7. When the heart rate drops below the low set point the PM will send sufficient electrical impulses to make the heart beat at least that fast. In other words say the low set point is 70n and your heart's natural PM is not sending enough electrical impulses to keep your heart beating that fast. That is where the manmade PM comes in and keeps the heart at 70.
As mentioned there are two set point and the PM watches both. The upper set point is doctor's choice. Based on what the dr knows about your heart function (for example my low setting is 80 and the high setting is 110) he will select the upper limit. When the heart rate reaches or exceeds the upper set point the PM continues to monitor but it quit sending impulses and will send no more until it determine that your heart rate will drop below 70.

There may be times that you will check your heart rate manually and find it below the low set point. This happens to me often and although it is only a few beat low I wanted to know why this was happening. The answer I got from the dr was that the electrical impulse generated by the heart's natural PM was not always of the same strength. Some would be too weak to complete a heart beat but would be strong enough for the pacemaker to detect. So since the PM saw an impulse it would not send one thus we have a skipped beat. In other words the heart's natural PM was faking out the man made PM.

I just saw the CardiacTechnician's comment and mine may contradict some of what he said. Of course he is correct and you should ignore my babble. But since I had already written this and writing is not that easy for me I wasn't going to throw it away.

Smitty

Back to basics.

by CardiacTechnician - 2013-07-21 05:07:39

In its original simplest form a pacemaker was there to stop peoples hearts going too slowly. If you heart goes too slowly you will feel dizzy or faint.
A pacemaker set to a lower rate limit (base rate) of 60 will therefore not let you have a delay between beats longer than 1s. so if the pacemaker was doing all the 'work' one beat each second would mean a lower rate of 60.
A pacemaker does not LOWER your heart rate it stops it going too low. In essence if your lower rate is set to 60 your heart will not drop below 60bpm.

The 130 is a little harder to explain but bear with me...

Now we all have a natural pacemaker in our heart called the Sino Atrial Node in healthy hearts our Sino Atrial node makes our heart go quicker when we are exercising... If you run up a hill your heart rate increases.

Now in some hearts that require pacemakers the signal from the top of the heart doesnt reach the bottom of the heart (Heart Block).

Lets take a scenario where a man has complete heart block and NO pacemaker (the signals from the top of his heart dont reach the bottom of his heart).

This man is asleep and his NATURAL pacemaker is going at 60 bpm.... but the bottom heart (ventricles) arent getting this signal (because of the heart block). So instead they contract at 30 bpm as a safety mechanism.
This person may feel faint or tired because the top of his heart, which dont do much in terms of pumping blood to the whole body are going at 60 but his bottom part (which does most of the hard work supplying the body) is going at 30.

Enter a Pacemaker, this gentleman gets a pacemaker, he has a lead in the top heart and a lead in the bottom heart. This allows communication between the two!

Now this gentleman is asleep his top heart is going at 60bpm again but this time the pacemaker can recognise this and Pace the bottom chambers accordingly. Now he has an upper chamber heart rate of 60 bpm and a bottom (paced) heart rate of 60 bpm.

This is great because this persons natural pacemaker is still working well and is being used by the pacemaker to know what rate to pace the bottom chambers of the heart.

There is also a sensitivity number which is the rate response upper rate... this is a seperate algorithm and i could explain that also if you wanted.

This gentleman runs up a hill.... his natural pacemaker in the top of his heart increases to 115bpm.... the pacemaker recognises this and makes the bottom chambers beat at the same rate. The top and bottom are now both going in synchrony at 115bpm.


This is all working well.... and will in your case work all the way upto your top number 130bpm.... so if you ran up a hill and your top heart was going 130 bpm the pacemaker would pace the bottom of your heart upto 130bpm also.....

BUT in your case 130 is the upper limit for this.... if your top heart was to go any faster your bottom heart would be paced no faster than 130 bpm..... the pacemaker would not track the heart rate in the top of the heart over 130.

There is a simple and good reason for this.....

If the top of your heart went into an arrhythmia like atrial fibrillation, the top of the heart could be going at anything upto 300bpm... if the pacemaker made the bottom of your heart go at 300bpm you would be in big trouble! so they dont.

The Upper rate limit 130 is basically saying that your heart is likely to go up to that rate in a natural physiological manor... however anything above this should probably be ignored as it may be pathophysiological i.e. something not normal which should be ignored.

Younger people therefore tend to have a larger upper limit i.e 60/180 as there heart can naturally go faster through exercise.

Hope this helps, its not easy to explain without diagrams!





















Heart Rate

by CardiacTechnician - 2013-07-21 06:07:07

Maximal Heart rate is calculated for all people pacemaker or not by 220 minus your Age. If you are 60 then 220-60 equals 160 therefore your heart shouldnt really exceed this....

Obviously this is a rule of thumb...
I'm 30 and I would struggle to get up to 170 on exersion!

When we implant pacemakers we use a whole range of information to decide on what upper rate is best for you... this is adjustable after implant.

Ultimately in its simplest terms your have fully understood that if you were in complete heart block and your top heart was going at 170 the bottom would be going at 130.


There are other factors that effect this such as mode switch algorithms.

The sensitivity number relates to rate response. In our previous example a person had a healthy natural pacemaker Sino Atrial Node....


Take a patient who had a heart rate of 60 but because of disease when they ran up a hill the heart rate didnt increase...
Enter a pacemaker, the pacemaker can use vibration (through a piezo-electric crystal) or impedance at the end of the lead (using a closed loop algorithm) to assume that person is exercising....

This will then gently increase the persons heart rate when they start to exert themselves.

if that sensitivity number is set to 115bpm.... when that person is exerting themselves the pacemaker will increase its rate accordingly up to a maximum of this rate.

Please understand there are so many variables and this is in its simplest form.

Upper Rate Limits i.e. 130bpm only need reviewing if you feel light headed during hard exercise. Upper rate behaviour in pacemakers is a pretty difficult meaty subject including 2:1 and Wenckebach behaviours.

Ultimately if you feel good with your pacemaker then the lower and upper rate limits are probably right for you! If its not broken dont fix it, and dont worry about it :)








Thank you Cardiac Technician and Smitty for quick response

by Duke999 - 2013-07-21 06:07:18

Thank you for your explanations. This helps tremendously. Now, correct me if I'm wrong. If I exercise by running on a tread mill and my heart rate goes up 170 and if my setting is at only 130, does this mean, my upper heart is beating at 170, but my bottom heart is beating at only 130 due to PM setting? This means the top and bottom heart are not beating in sync ? Is this bad?

Also, Cardiac Technician, you mentioned about "sensitivity number", would you explain how that works? I look forward to reading your reply. And Smitty, if you know that "sensitivity number", I would love to hear from you as well. Thank you both again.

Hmmm

by Casper - 2013-07-22 01:07:58

I find some of Cardiac Tech's formual for the upper rate setting debatable, the "general" formula you privided is just that, "general", but for somebody whose been athletic all their life, that formula may not be applicable.

I've been running for over 30 years and my upper rate limit has been removed, I've gone over 180 bpm, without any difficulty.

When I first had this "science project" implanted, I had the generic settings 60/130.

What happened to me was, each time I came back from a jog, shortly after that, my heart would pick up that pace for 2 minutes and speed up my heart.

I did not like this feeling at all, I wasn't aware at the time, but my EP took it upon himself to turn on the "Rate Drop Response" without my knowledge. He did not take into consideration I was a trained athlete and have a fast heart rate recovery. Since the, my lower rate has been set at 40 bpm and my upper rate has been removed.

Pacemaker can be very complex and each person is unique.

Good luck Duke with your upcoming visit on Friday.

Your setting sound like the factory settings and I hope you get the settings right for you, especially if you are athleltically inclined.

Casper

Casper

Me too

by kimbo - 2013-07-22 04:07:51

Iv got these 60/130 settings and iv been totaly fine untill i use the crosstrainer at the gym 5 mins in and am fluttering skipping and jumping catches my breath i slow down as it scares me silly i then resume and it can happen again or goes away i dont always get it everyday some days i can train ok i assume im hitting my upper limit and maybe going into 2:1 block??? i had my pacer done in march this year for brady, pausing i also have whenkiback block too worse at night my pm has sorted my symptoms im just not happy in the gym.

kimbo

You are ofcourse correct.

by CardiacTechnician - 2013-07-23 08:07:17

In that each person is very different and the Lower Rate and Upper Rate figures need to be set appropriately. I was simply explaining what these figures are and in no way say they are the 'correct' settings for any individuals. I felt that Duke just wanted to know what the number 'meant'.

It is stupid to discuss any individuals settings on a forum without all the information I simply explained the concept.

P.S. you cannot switch off an Upper Rate Limit in a Dual chamber pacemaker. I think its important that people understand this.

When discussing a rate drop response algorithm depending on the manufacturer you could lower the lower rate that the algorithm uses to trigger intervention or remove the drop rate criteria which could be used in an athletic type whose heart rate quickly returns to a lower rate after exertion.

Kimbo

by CardiacTechnician - 2013-07-23 08:07:22

Kimbo, I would book an appointment to get your pacemaker checked and explain your symptoms in the gym. It is quite plausible that you are experiencing some form of upper rate behaviour (such as 2:1 or Wenckebach block). At our centre we often suggest exercise tests for patients so we can decipher which settings are best for them.

I wish you all the best Kimbo

Cardiac Technician

Note to Cardiac Tech

by Casper - 2013-07-24 02:07:03

Each pacemaker is unique and have various settings, all I can say is that my upper rate limit is indeed turned off, per my detailed report, I received after each visit, also my discussions with the Medronic customer service phone line.

I was simply stating that my experience in "general" is that soem doctors and I guess I can include pacedmaker technician don't always come into contact with people who are athlectic and fall back on the general forumula.

I totally agree with you, discussing individual settings is foolish, without know somebody's complete history.

I think you bring a wealth of information to this forum.

All the best,
casper

Question for CardiacTech

by PV Gringo - 2018-01-09 18:23:57

You state, "Ultimately if you feel good with your pacemaker then the lower and upper rate limits are probably right for you!" And if you don't feel good with your pacemaker, does that mean the lower and upper rate limits are probably not right for you? If so, how would you know whether it's the lower, the upper or both that are wrong?

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