heart rate below base rate?

Has anyone had issues with measuring their heart rate using the "old fashioned" way of feeling pulse and looking at second-hand clock and using electronic heart rate monitor and finding the heart rate below the base set rate of PM? I thought it was never supposed to go below that set rate.

Any thoughts?

6 Comments

depends

by Tracey_E - 2013-04-08 04:04:27

How much below? If it's a few beats, it could be counting error, could be small beats you missed, could be that your hr isn't exactly 60 (or whatever your min is). It's not set in beats per minute but per second so if you are at 60 bpm, that's one per second so it won't let you go more than a second without beating. Over the course of a minute, it may not work out to exactly 60.

Get a finger pulse oximeter!

by cb - 2013-04-09 05:04:59

these things are great! It gives accurate pulse rates as well as oxygen saturation, keeps you from having to be around a clock and can be taken anywhere...I take mine to the gym. I got it on Amazon for $17...it is worth it!

age

by Tracey_E - 2013-04-10 01:04:34

How old are your leads? Over time, they can develop enough scar tissue that the pm puts out the signal but the heart doesn't get it. They can tell by the interrogation report if the pm is trying to pace or not. As long as you feel ok and it happens rarely, I would probably not worry about it. I assume they tried turning it up?

Thanks for replies!

by inGodsheart - 2013-04-10 02:04:47

Hi, All!
Thank you for everyone's helpful replies. In answer to TraceyE's last question, my leads are brand new as I just had PM implanted Feb. 15. My base rate is set for 65, but I measure my HR below 48 at times, but then a couple seconds later, I measure and the reading is at its base rate of 65. Evidently, at the time I'm feeling bradycardic, my device is doing its thing and then brings my rate to its proper level.

In response to cb about the pulse oximeter, I've tried this several weeks ago, and the readings were always very skewed. I then read the instruction manual, which indicated people with PM shouldn't rely on the readings of an over-the-counter pulse oximeter because the readings are often false. I'm glad it's helpful for you, though.

I remember at my recent interrogation, the tech saw this for himself and said the device kicks in after one beat when HR drops below base rate. This must be when I feel the rate change.

I have my PM for several reasons. One is severe dysautonomia which causes pre-syncope episodes induced by both low and high blood pressure and low and high heart rates. I also have tachy-brady syndrome. I also have a neuro-muscular disease that requires me to take a medicine called Mestinon to improve muscle strength. One of the side effects of Mestinon is reduced heart rate. Since it's imperative I take Mestinon for the muscle disease, my cardiologist has to work around the side effects; however, he was going to implant a PM anyway.

I'm very thankful to have found this site as it's obvious the members are knowledgeable about PM and seem to be veterans in the field. :)

Blessings on everyone's day!

Been there - twice

by Ramnarayan - 2013-04-10 10:04:31

On feeling very tired, I timed my pulse at the wrist using the wrist watch. On both occasions, I measured 35/39 beats. PM was set for 60. The Drs and Medtronics think that my heart is not capturing the beats sent out by the PM (Model Sigma 1st time, replaced by Adapta at the 2nd time). PM beats showed up in ECG. Leads are being blamed, though the opinion is divided. No answers and no solution so far. I am doing fine since the last episode, 75 days ago w/o any recurrence. I would be grateful if any one can explain what happened.

I'm not sure of your Tech

by donr - 2013-04-12 12:04:12

My PM does NOT wait a beat to "Kick in." At least not the way my cardio explained it to me.

Mine monitors my heart at all times & during every beat. It is prepared to "Kick in" during ANY beat because it has programmed times for each event & if the appropriate event does NOT occur when the PM expects it to, it supplies the needed signal to make the heart function. That's why it can pace you 100% of the time.

That, BTW, is how your native heart's control system functions. Each & every beat is individually & independently timed by the two nodes - the SA & AV. The SA Node is the master clock that starts everything for every beat by triggering the Atria to contract. The AV Node gets the signal from the SA node & after a delay, causes the ventricles to contract. After both sections of the heart have contracted, the timing sequence starts over for the next beat. Your PM monitors the elapsed times for these events & if they do not occur on time, a very short while after they are expected, the PM sends a signal to the heart to do whatever did not happen on time.

The heart does NOT drop below the base rate. What happens is that a single beat will take longer to occur than it should, based on what the Base rate is. F'rinstance - if your base rate is 60 BPM, each beat takes 1 second on the average. If a single beat takes too long - either for the ventricles to contract (which is only a part of that second) or for the next beat to start, (which is the full second) the PM steps in & does the job. Perhaps your tech is saying that in his own way. If the next beat after the bad one is the proper elapsed time, the PM does nothing.

A word about the elapsed times involved: The events of a heart beat are measured in thousandths of a second - called milliseconds (ms). If your HR is supposed to be 60 BPM, that is 1 second for a single beat - which is 1,000 milliseconds. A typical elapsed time the PM is looking for some event is 150 ms. The PM will act in typically 160 ms if the event does not occur after the 150 ms. That means that there is only a 10 ms longer time before the event occurs. You cannot sense such a small amount of time.

If you watch the HR reported on an Oximeter, you will see that it bounces all over the place - & you never sense a thing. I watched the oximeter for nearly a full minute during my last visit to my cardio last Tues. MY HR was reported by the device after EVERY beat, & bounced around between 79 & 84 BPM - & I'm 100% paced! My lower limit is 75 BPM. The PM is adaptable & runs at the rate the heart is directed to run based on the body's needs for Oxygen at the time. So, in my case, it kicked in during every one of those beats & I could not feel any difference among the beats.

Don

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