Can you explain PM rates upper limit?

hi all:

I'm quite new to pacemaker life (since Nov 2015), and I have a quick question about the settings.

I'm set for 60-130, and I'm comfortable with those rates.

I understand the lower setting (60) paces me up to 60 when my HR tries to go lower, but what does the upper setting do?

I have an upper setting of 130, but on the cardio machines, my HR goes up to 155. I feel fine with it that high, but I was surprised because I thought the 130 limit of my PM meant that I could go no higher than 130.

It's very possible that the cardio machine isn't an accurate read of my HR, but either way, can you help me understand the role of the upper limit of my rates?

My PM is rate responsive, if that helps.

Thanks, friends.

AJ

4 Comments

Two upper limits

by IAN MC - 2016-01-03 01:01:11

As has been said, the MaximumTracking Rate ensures that your heart will beat in a normal way up to that point ( atria then ventricle )

But as you have Rate Response switched on you will also have an Upper Sensor Rate . This means that when you exercise RR will only put in extra beats up to that limit.

Drs are reluctant to set the Upper Sensor Rate higher than your maximum safe heart-rate as defined by 220 minus your age or some similar formula.

Usually the Upper Tracking Rate is set slightly higher than the Upper Sensor Rate which make sense as you wouldn't want Rate response driving the HR above the tracking limit which could cause erratic heart beats in some medical conditions.

Ian.

Very helpful--thank you

by ac2526 - 2016-01-03 05:01:39

Thanks, y'all. Very helpful. I get it now. :)

AJ

What is being paced and why?

by BillH - 2016-01-03 05:01:55

There are a number of ways that PM can be used for a number of different conditions.

Also there are a number of different setting that have upper limited.

You don't have anything in your bio, but looking back at your last message I see that you have a two chamber PM and it paces the atrium most of the time and very rarely the ventricle.

Basically the upper limit is the maximum rate that the PM will generate pulses to pace the heart, but as I said that number(s) can be applied to several different functions in the PM.

Nothing in the PM can limit the natural pacing of the heart.

It appears that your sinus node normally has problems pacing and thus the PM. But under exercise it (or some other atrium cells) fire regularly enough tio pace the heart and AV node works properly to follow that atrium and trigger the ventricles.

pacing

by Tracey_E - 2016-01-03 12:01:57

It will only pace you to 130. Your heart an do whatever it wants on it own, the pm will only sit back and watch.

If you are in av block, an upper limit of 130 means it will only pace the ventricles up to 130 bpm.

If you are using rate response because your rate isn't going up sufficiently on exertion, it will only pace the ventricles to 130.

Machines are notoriously inaccurate with us so when in doubt, count manually. If you feel good, no reason to count at all, trust that whatever your rate is is sufficient.

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