Pacemaker Dependency Questions

Is there anyone out there that can explain what it means to be "pacemaker dependent"? I am interested in the difference between someone with a non functioning av node and someone with a non functioning sinus node. What is the definition of pacemaker dependency and does it matter which node is non functioning? I see a lot of people here who are primarily paced in the ventricle vs those that are primarily paced in the atrium. What kinds of conditions define the difference? I guess I'm looking for a cogent discussion of these issues because so far I haven't been able to get answers from the docs.

13 Comments

The difference

by Terry - 2008-01-05 05:01:40

If you only need atrial pacing support, that is fortunate. Your AV node working provides for a natural ventricular contraction. If you need ventricular pacing support, it's best to see your EP about the possibility of His bundle pacing, otherwise the latest scientific literature suggests that you may be in danger of contracting heart failure or stroke. If your EP doesn't do pacing that makes use of the heart's conduction system, it's fairly well known who does. Though times are changing, the lower chamber lead is often still placed in a position that bypasses the heart's conduction system. Thanks for asking.

Terry

paced in ventricle

by Meerkats - 2008-01-05 06:01:08

I have complete congenital heart block, which means there is zero conduction between the upper and bottem chambers of my heart. The atrium was beating normally, but there was no conduction system to deliver it to the ventricle to tell it to beat. (this is strictly an electrical problem, not structural.) Somehow, using some sort of "backup" in the ventricle, it did beat...but on it's own and not efficiently and there was no way to know when it might just quit.

So I'm paced at 0% in the atrium and 100% in the ventricle. Basically, my pacer reads my natural upper beat and tells the bottom to follow appropriately.

It's allowed me to go from a resting of below 50 to a resting around a more normal 70. And, it allows me to exercise up to 175 instead of never being able to go past 100.

Oh, and that other minor thing that it protects me from sudden cardiac death. :)

Thanks for answers

by TwoCents - 2008-01-05 06:01:24

I truly appreciate the discussion. In my case I need pacing 100% of the time in the atrium. I have a lead in the ventricle and I understand I pace 40% there. My sinus node is damaged. If an atrial lead were to fail or malfunction it's my understanding that the ventricle would continue to provide contractions because of the ventrical lead, albeit at a slower rate. Again thanks for taking the time to help us all understand the biology.

HELLO

by SMITTY - 2008-01-05 07:01:02

TwoCents, I'm sorry, the Gremlins got to my keyboard and caused me to misspell hello. Smitty

Pacemaker Dependency

by SMITTY - 2008-01-05 07:01:49

Hell TwoCents,

Your question is "Is there anyone out there that can explain what it means to be "pacemaker dependent"? I'll take a stab at that one. (I should add right here that I have read any other replies you may have received, If I contradict something in one of them take their word for it) A person is considered pacemaker dependent when most of his or her heartbeats are supplied by a pacemaker. To me that says there are degrees of pacemaker dependency. If you heart depends on your PM to help it beat 25% of the time you are 25% PM dependent. On the other hand if your heart depends on the PM 100% of the time, well let's just take good care of your PM.

The Av node acts as an electrical gateway to the ventricles delivering the electrical signals from the atrium to the ventricles. To give you more information on the nodes and the chambers of the heart getting an electrical impulse to beat, be it from the heart's natural pacemaker or the manmade job many of us have, let's start with the following:

The sinus node is the heart's natural pacemaker. The sinus node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). The electrical impulses are generated there. The sinus node is also called the sinoatrial node or, for short, the SA node.
The electrical signal generated by the sinus node moves from cell to cell down through the heart until it reaches the atrioventricular node (AV node), a cluster of cells situated in the center of the heart between the atria and ventricles. The AV node serves as a gate that slows the electrical current before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated. After passing the AV node, the electrical current travels to the ventricles along special fibers embedded in the walls of the lower part of the heart.

From my view point it makes little difference which of the chambers, atrium or ventricles requires help from a PM to beat because without that help we are going to be in deep trouble. Of course to the EP or the technician doing your checkups it makes all the difference in the world as they must have this information for you to have a viable PM.

I wish you the best,

Smitty

Now I'm Gettin' It

by TwoCents - 2008-01-05 08:01:55

Thanks to all! Smitty, that is a great description of the electrical conduction system of the heart. When one hears the words "pacemaker dependent" the unspoken fear is: "Ok, how much trouble in I am if various components of this doodad fail?" I'd just like to know where I stand and then get on with life. I'm the one who wants to know and understand everything, so I can put it all in proper perspective, so again thanks for the discussion. TwoCents

Hi!

by tcrabtree85 - 2008-01-05 10:01:12

I find you topic very interesting. Smitty gives a great response. I am 99.9% dependent on my pacemaker. I had my SA Node taken out. I have pretty much a little tiny part left that will beat a little. When I get a pm check they turn down it down to see where my heart will take a beat I get a beat at 50 that will drop within seconds. To me that helped me knowing that I had a little beat still left so if something happened to the pm inside me I would have a little while to get help.
I do believe that each condition is different and where you are paced does make a difference. Though we are all very blessed.
I don't know if this will help you or not but good luck at learning how it all works. It's very interesting once you start learning more about the pm.

Tammy

Wild Ride

by TwoCents - 2008-01-06 01:01:53

Bunnykins, it seems like many of us have had a wild ride. I too started out with some atrial activity, but upon my recent change out it was determined that I now have none. The pm tech openly discussed how they were going to accomplish the change out, i.e. did I need transvenous pacing during the procedure. He decided that he could leave one lead attached to the old while the new one was being put in and then switch the other lead. The way he put it was "I think I can do it this way." Yikes!, I was the one on the table and I meekly piped up and said. "You think?". He then said he could do it. My confidence wasn't at a high level after listening to the discussion all trussed up like a Christmas goose, but everything did work out ok. My pacer had migrated so I was there longer than anticipated, but all's well that ends well. I guess this is my quest---I want to fully understand this pacemaker business and all the nuances, so that I am armed with some good info next time the med people are talking around me as though I wasn't there. I'm now going on 7 years in this business and still don't feel like I know all I should. Settings for example are a mystery in terms of what does what to make us feel better. So, I will continue to be a pain in the behind and ask questions of the medical people until I really get it.And that's just my two cents worth. Best to all of you-TwoCents

one more thing

by Meerkats - 2008-01-06 03:01:23

I forgot to mention that while I'm paced 100% in the bottom chamber, my life did not/does not necessarily rely on it.

What I mean is that if the pacer malfunctioned, I do have an underlying rhythm that would take over. I was asymptomatic from my heart block (other than cold feet and low heart rate) but it was the risk of whatever it is that makes the bottom chamber beat independently of an an electrical impulse from the top chamber just quitting someday causing sudden cardiac death.

In fact, now that I can get my rate up past 100 when exercising, we've discovered that at about 150, a natural conduction actually takes over my pacemaker. So, while I'm consider complete heart block, there is still some conduction somehow. My doc explained that it most likely has to do with the placement of the electrical failure within the heart.

That said, I certainly don't want to risk having my pacer quit on me, since who knows when my natural back up system decides to quit.

Oh, and I actually have an ICD...it paces me for the heart block, but my first pacer recorded an additional problem with a serious VT episode at night...also asymptomatic. So, the ICD will shock me if that happens again.

I'm happy to say that yesterday was my one-year anniversary of getting the ICD and it was a shock-free year! Since I got the ICD just 6 months after my first pacer, making it through a whole year with no surgeries and complications feels like a big deal to me.

Sorry I rambled on!

Pacemaker Dependant

by peter - 2008-01-06 05:01:49

You are simply pacemaker dependant if your pacemaker is pacing, that is sending out pulses 100% of the time and if it did not the paced chambers being paced would stop beating altogether and you would then be at the pearly gates.Nothing to worry about. Im pacemaker dependant. Peter

Dear TwoCents re PM dependency

by bunnykin - 2008-01-06 11:01:55

I would like to share with you what being pacemaker dependent is like too. I'm almost 99.8% pacemaker dependent most of the time and I have an ICD implanted in 2004. My pacemaker was inserted in 2002 though at that time I wasn't dependent. As time passed in 2004 my PM was explanted to change to ICD due to VT. This time due to another arrhythmia from the AV node or the junction, I had junctional tachycardia and I began to be more and more dependent on pacing from both chambers, Atrium and Ventricle. Now being nearly 100% can be rather worrying cos if anything does go wrong with either the device or lead, we'll be in deep deep trouble. Last year when my ICD lead(ventricle) was perforating the heart wall, I needed an operation to replace the lead as well as device(battery also depleting due to high usage from treating VT episodes). Because of pacemaker dependency, before the surgery to remove both device and lead, I had a temporary wire inserted to pace the ventricle; That's one aspect of how dicey situation can be when one is PM dependent. This is cos when the lead and machine is taken out, there is no backup heartbeat from our own heart, so hence the need for temporary wire placed in beforehand.
Anyway, all went well with that operation; however, the new lead replaced unfortunately, is now being recalled by medtronics. That's another chapter of my life i guess. All the best to you TwoCents. Hope this helps as information for you; sometimes being fully dependent can be quite a concern. Take care.



biventricular pacers

by PreciousDays - 2008-01-09 10:01:36

The pacers that are an ICD - combined with ventricular pacing work 100% of the time - ie with every beat of the heart - however - just as noted above - if the pacer quits- the heart continues to beat, albeit out of synch. Those of us with biventricular pacers are 100% paced - but not 100% pacemaker dependant. In fact - calling these devices pacemakers is actually a bit of a misnomer, as they don't actually set or change a pace for us - unless of course our hearts beat terribly fast, in which case the ICD will (hopefully) jolt us back down to something more survivable. -

My question to others is - are there three lead pacers that aren't biventricular devices? or when someone has three leads does that always mean it's a biventricular one? thanks.

PD

Hi PD/Bivent.ICD

by bunnykin - 2008-01-10 07:01:11

Interesting question indeed. Recently when I had problem with VT as well as JET or junctional ectopic tachycardia which my EP dr sighed and told me that was rather uncommon, ie. to have double tachycardia esp. the JET, he said sometimes bivent. ICD might help for some. I understand that currently bivent. devices basically assist people with heart failure and paces them evenly and also minimizes breathlessness which very often CHF(congestive heart failure) patients frequently face. However, on the subject of dependency, altho not all such patients are 100% dependent, but if and when they actually are told they are dependent, when the leads or device malfunction, we have to pray very hard and hope medical help is nearby. Myself included I'm with ICD, multiple complications( lead now on recall) and also my dr also recently discovered that there was hardly any "escape rhythm" during my last checkup. So he said all these problems being present, we should just be very vigilant and monitor often. Let not our guards down. So now the question of dependency is clearly, do we have an escape rhythm, just in case our device fails, be it ICD or PM...that's most important. If there's escape rhythm, we can perhaps tide ourselves over a little before we get to the hospital. For now, I think, 3 leads mean Biventricular and usually in ICD; It's the answer to CHF patients. :)

Bunnykin


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