How does a PM work?

I've still yet to understand how a PM works; the PM tech are not much help.
Can someone give a layman's version of how this thing works?
I went in for Atrial Fib ablation. After the ablation, my heart would not stabilize, sometimes goes very slow, pauses a few seconds then resumes. So, they put in a PM to correct that.
The PM is set at 70; from what I understand, if my heart rate goes to below 70, the PM kicks in. Now, does that mean the PM "takes over"? if so, what happened to the heart's natural LOWER beats? Or, does the heart just follows the PM stimulus pulses? Then, how would the PM know when the heart rate is above 70 and turns off( if the heart now just follows the PM at 70)?
On the other hand, if the heart does not follow the PM at 70, then how does the PM regulate and incorporate the heart's own beats to get a regular heart beat at 70?

Ken

6 Comments

computers are so cool :o)

by Tracey_E - 2008-08-15 04:08:33

I'm fascinated by the technology in pacers! They're so stinkin smart. I mostly track ventricle so mine works differently than yours but the pacer tracks what your heart is doing all the time.

If you can't go below 60 bpm (the math is easier so I'll use this instead of 70!), that works out to one beat per second. If your atria is beating more than once per second, the pm just watches. If your heart goes a second without beating, the pm makes it beat. It might beat on it's own in the next second, or if it doesn't, the pacer will do it for you. The pacer will always give your heart a chance to beat on its own first.

The ventricle will follow what the atria does so your ventricle only beats when prompted by the atria. In my case, the ventricle never gets that prompt so every time the atria beats (on its own), the pacer makes the ventricle beat also. In your case (I think, I really don't know much about ablations) once the atria beats- either on its own or with the pm- the ventricle will beat also. If it doesn't beat within the amount of time it should on its own, the pm will make the ventricle beat too.

Ken

by Tracey_E - 2008-08-15 05:08:03

Just because it feels like you're skipping a beat doesn't mean you are. Little beats you can't feel are still beats. Ask them next time you get it checked, they can tell you how often you're hitting your lower level and confirm that you haven't gone under it. Or they might need to adjust your settings. They can change the timing, increasing or decreasing the time they give your heart to do its own thang.

Hi TraceyE

by Ken(Toronto) - 2008-08-15 05:08:12

Thanks for the explanation.
Today, my heart is skipping beats. The PM did not fill in the missing beat, but kicks in 1 second after the missing beat; so the end result is, I'm still missing that beat....is this normal? Shouldn't the PM kick in right away when it detects the missing beat to fill-in the beat so that no beats are missing?

Ken

Hi Ken......

by Bionic Beat - 2008-08-15 05:08:17

As a relative newbie, I can't answer any technical questions but did you have a Pulmonary Vein Ablation?
Or the AV Nodal ablation?

Just curious as to where you had this done and by whom, or just even where? Did you get into the study at Southlake?

I had an AV Nodal Ablation after my pacemaker was implanted.....for very fast, irregular AFib.

Got "proper help" at TGH.

You can send private message if you prefer to not post the information.

Thanks.


Bionic Beat

How Pacemaker Works

by SMITTY - 2008-08-16 02:08:44


Ken,

My answer to your question "how does the PM regulate and incorporate the heart's own beats to get a regular heart beat at 70?", is that the manmade pacemaker is constantly checking your heart to see if the heart's natural pacemaker will send the needed electrical impulse to make your heart beat before sending one itself.

You see a pacemaker does not just automatically send an impulse to make our heart beat, unless you are 100% pacemaker dependant. In that case the manmade pacemaker has to take over the job normally done by the heart's natural pacemaker. Since most of us have hearts with partially or "sometimes" functioning natural pacemakers, the manmade job has to check to see if it is needed before it sends an impulse.

Now the ringer in all this is the heart’s natural pacemaker can fake out the manmade PM. This happens when the heart's natural PM sends an impulse that is too weak to make your heart beat, but the manmade PM detects that weak signal, thinks it is a good signal and decides to sit out that beat and then checks the next one. This can result in what are variously called skip beats, PAC or PVC. Now I know I'm implying all of these are one and the same, which they are not, but to many of us they feel about the same and the result is pretty much the same. Our pacemaker will not maintain a regular heart rhythm because it is detecting what I describe as false signals from the heart natural pacemaker. This can result in our pacemaker allowing a heart rate that is a few beats below the low set point on the pacemaker.

Smitty

Bionic Beat

by Ken(Toronto) - 2008-08-16 07:08:29

Tried to send you private mail, but system says you're not a "valid user"?!

Ken

You know you're wired when...

You know the difference between hardware and software.

Member Quotes

I had a pacemaker when I was 11. I never once thought I wasn't a 'normal kid' nor was I ever treated differently because of it. I could do everything all my friends were doing; I just happened to have a battery attached to my heart to help it work.