Pacemaker rate

pacing heart block

by Tracey_E - 2018-07-06 18:03:07

They would usually turn it down so that we pace less. As long as we still feel good, it's best to try to pace as little as possible. 

With heart block, the lower limit doesn't usually matter much because that refers to atrial pacing. We mostly pace ventricle. The sinus node in the atria measures oxygen and raises/lowers our rate accordingly.  It sends the signal to the ventricles to beat. With heart block, that signal is blocked so that's where the pacer steps in. It gives the ventricles a fraction of a second to beat on their own, then it kicks in with pacing. If the atria gets slower than the lower limit,it'll pace atrial too, but mostly the pacer plays follow the leader and our own heart is setting the pace.  

If they have the lower limit at 60, then upper 50's is acceptable because it's close, but closer to 50 is worth a call to the doctor. How are you counting 50? Often monitors are not accurate with us, the pacer confuses it. Or there can be little beats between the stronger beats that we miss when we count manually so it's really higher, we just aren't counting them all. So it's entirely possible that his rate is higher than you think it is. When in doubt, call and ask to have it checked out. Don't worry yourself when a quick phone call can put you at ease. 

p.s. I have congenital complete heart block, also. I'm probably old enough to be your mother, healthy and active, currently training for a half marathon with my oldest kid, next vacation will be hiking and canyoneering with my youngest kid. Having CCHB hasn't slowed me down or kept me from living life to the fullest. I'm sure it's scary for you now as his mom, but there's no reason he won't have a bright, beautiful future. 

Pacemaker

by Bridget89 - 2018-07-06 18:20:21

Hi Hun,I’m not manually counting his heart rate,the cardiologist told me yesterday the pace maker is set at 60bpm wen baby’s active,then he’s set it to 50bpm wen baby’s not active eg sleeping,I don’t understand why he’s done it to be honest,the baby had the pacemaker fitted because he’s heart rate was 45 and he’s heart started to swell,-and the baby was getting poorly,I explained this to him and he sed the main reason the pacemaker is there is incase the heart ever stopped,but from what I’ve read if a heart stops beating the pacemaker will to,honestly I dnt really understand,he knows my baby suffered yet has still turned it down lower,he said if it’s pacing all the time then it can cause problems? Is this true?its nice to speak to someone with the same problem as my son and knowing your are living a happy life,I hope u are well and thanks for replying to my comment. X

Heart Block

by AgentX86 - 2018-07-07 00:02:29

His heart rate was 45 because his AV node wasn't conducting his natural heartbeat from the atria to the ventricles so some other part of the heart was taking over that function for the ventricles (known as an "escape rhythm"). The heartbeat you count is the ventricular rate, not the atrial rate.  They're not supposed to be different but in the case of a complete heart block, they are and while your son's atria are beating at the rate dictated by his body's needs, his ventricles were being paced by this "escape rhythm".  You're count this "escape rhythm" (45). 

Your son's pacemaker is primarily there to compete the circuit the AV node is supposed to do, so the atria and ventricles will be in synchrony.  If, for some reason, the SI node (the atria's natural pacemaker) doesn't function properly, his pacemaker will also take over pacing the atria at that "minimum rate" (50 or 60, or whatever). Unless the SI node is damaged, too, it shouldn't get to that point.

Someone posted a link to this book recently.  I haven't finished it yet but it's really done well.  I recommend that you read it.  It will answer a lot of questions a parent, such as you, will want to know.  It should help you communicate more effectively with your son's EP, as well. BTW, the Kindle version is really cheap, so no excuses.  ;-)

<https://www.amazon.com/What-Pacemaker-Cardiologists-Providers-2013-05-09/dp/B01K15I028/ref=sr_1_2?ie=UTF8&qid=1530932330&sr=8-2&keywords=what+is+a+pacemaker>

Babies & PM's

by donr - 2018-07-07 01:25:53

Mom, you are rightfully concerned - for two reaasons:  1) You are the Mom!  2)  The baby has a very real problem that you do not totally understand.  Let's start by understanding how a PM works - that alone will relieve your mind!

The modern PM works on demand, meaning it only paces whwen it needs to. It sits there ands monitors the heart - EVERY beat of it.  It uses the same leads it sends "Beat" signals over as monitoring leads.  When it is not sending "Beat" signals, it is "Listening" for certain electrical activity generated by the heart.  The first electrical activityy it is looking for has a name - it is named the "P wave."  The Pwave is the naturally occurring electrical signal that shows that the top half of the heart - called the "Atria," - is beating.  This wave comes from the "Sinus Node."  This node was mentioned by several other comments above mine.  This has NO relationship to the sinuses in your head.  It is a special group of cells in the top of the heart which acts as the master clock for the heart; they generate electrical waves that make the heart work at the correct rate.  Specifically, they generate the P wave that activates the Atria to beat; it then trravels down the heart to another node  (With a name, of course), called the AV Node.  AS it hits the AV Node, it causes that node to make the bottom half of the heart beat - the bottom half has two chambers, the Ventricles.   When they beat, they pump the blood & create the pulse you feel.  Your son has an ELECTRICAL block that keeps the P wave from getting to the AV node, so the ventricles never get the signal to beat normally.  The designer of the heart's electrical system was one smart dude - HE/SHE built in a backup system, called the ESCAPE RHYTHM that is generated in the AV Node.  It takes over if the ventricles don't beat, so it is a bit slower than the normal heart rate.  that keeps it from interfering with normal events.

I kinda got distracted, so back to the PM & how it works.  The lead going to the top half of the heartsenses tha P wave of what should be a normally beating heart, so it switches to the second lead going to the ventricles & awaits the arrival of the P wave there to make the ventricles contract. If it senses it & the ventricles do their thing, it cycles back to sensing for the next P wave for the next beat.  If it does NOT sense the ventricles beat, it sends a pacing pulse to make them beat.  In your child's case, it should never detect  ventricle beating because of the complete block. 

So the PM FOLLOWS the natural rhythm of the heart.  If the Sinus node beats faster, the PM will follow & beat faster.  If the sinus node slows down, the PM will follow & slow down. 

Now - since your son's heart has a normally functioning sinus node, the PM can be set literally anywhere below the lowest naturally occurring rate of the Sinus Node.  As soon as the PM senses that P wave, it knows that the heart is beating alright - at least in the top half where heart rate is determined. 

A significant point:  There is NO setting on the PM for "Beats Per Minute."  The PM is an expensive stop watch; it is a timer!  They set the PM for 50, 60, 45, 55, etc Beats Per MInute  by adjusting the length of time between beats that the PM looks for.  If the heart rate is supposed to be 60 BPM, the time is set at 1 second; if set for 50 BPM, the time is set for 1.2 seconds. 

So what does the lower limit mean? It is a HR below which the PM will totally take over & run the whole show.  Supposing the heart malfunctions & wants to run at 50 BPM when set at a 60 BPM lower limit.  The PM is looking for 1 second intervals between beats, but they are not coming at that rate, the PM generates the signals to make the heart run at the correct rate.  Tracey mentioned letting the heart do as much as it can - hence setting the lower limit as low as possible so the heart can run things.

read this article for some good info on what a baby's HR should be & how to measure it yourself.  https://kidshealth.org/en/parents/take-pulse.html.

The best to you & your baby.  May he live long asnd prosper!

Donr

Whoops! FVorgot to mention...

by donr - 2018-07-07 11:28:50

...If the Heart stops, the PM DOES NOT STOP!!!!...  The PM just keeps pacing like the heart is still functioning.  In the extreme - if a PM host dies, the PM will keep pacing till the battery runs out, possibly years after burial. 

To prevent the heart from stoppin g is one of the reasons for the design of the PM.  Not to worry, Mom.

Donr

no answers, but some other questions

by Gotrhythm - 2018-07-07 16:27:15

I confess to complete ignorance on the subject of pacemakers in babies. That said, I think your questions are entirely resonable and that your doctor should be able to answer them to your satisfaction. Try making friends with his nurse. Sometimes they are much better at explaining things than doctors are.

I'm only guessing, but one reason he may have turned down the HR was to conserve battery life. The less the pacemaker works, the longer it will last. The longer it lasts, the longer it will be before it needs to be replaced.

But like you, I would question why it would be set to 60 while awake and 50 when sleeping, especially since the baby was struggling with a HR of 45. In adults those settings are pretty standard, but should it be the same for a baby?

The answer might have to do with how a pacemaker works in cases of heart block. There's a really great youtube video that explains it. I'l private message it to you.

But when it comes to settings I would imagine the same thing is true for children as for adults. What's right is what works. If adults feel okay and they are able to do what they want to, then their settings are right.

So. Does your baby seem happy and active? Is he hitting his milestones? Does he sleep a normal amount? not too much or too little? Are his eyes bright and his color normal? How's his appetite? Is he gaining and growing? That's what matters, not some pacemaker numbers.

About the heart stopping. Don't know what you read but Donr is right. The pacemaker's job is to keep your baby's heart going. Anytime it fails to beat on it's own, the pacemaker will supply a beat.