Impedance checks

Hi everyone
I recently enquired about the 3 pulses that I feel in the pacemaker every 3 hours and a few of you suggested that it was an Impedance check.
OK so a gather that it is checking the wires to see if there is a fault; but what happens if there is?
Do alarms bells start ringing, does it immeadiately dial 999 or in the case of the US 911, do my eyes start flashing warning warning, what??

It is a pity these little miracles do not come with a user manual!!


Hi Wingart,

by Gellia2 - 2007-12-12 08:12:07

Here is a question I posed to an EP online along with his answer regarding impedance check. Hope this helps.
Best to you,
MedHelp Member's Question
Impedance Shock
Oct 06 by Gellia
Tags: shock, pacemaker, Heart, unipolar
I recently had a Medtronic EnPulse implanted in July. It is my seventh pacemaker (first was 1975) and I have 26 year old unipolar leads (Medtronic 6957 and 6957J). Recently I have been able to feel the impedance check every three hours in the form of a shock that makes my muscle twitch.
My appointment with my EP is not until Oct 16th. Everything else seems to be OK and phone monitoring revealed nothing out of order. Just quite a jolt every three hours without fail.
Is this something I should deal with immediately or can it wait until my appt?
Thank you.
Doctor's Answer
Oct 06 by ForumMD-MJM

View Profile
36 years old
Wilmington - NC

That is interesting, you taught me something. I called Medtronic's technical support line. The EnPulse has a new feature that tests lead impedance as you describe every three hours at 5 Volts and 1 millisecond, far more than your normal pacing threshold. Because your lead is unipolar and the pacemaker can is an active part of the circuit, you can have pacemaker pocket stimulation.

The autoimpedence check is not a vital part of the system and can be turned off. There is not danger to waiting, but if it is keeping you awake at night or there is significant discomfort it can be turned off. If you need it done now, you will have to get a hold of your doctor. My local Medtronic representative was telling me last week that he reprogrammed a device in a local diner last week because that is where the patient was and he didn't want them to go the ER on the weekend.

The short answer is that it can wait if you can.

I hope this helps and thanks for posting.

Wingart, if you have any other questions that I can maybe help you with, send me an email and I'll let you know exactly what I found out. It's not to check for a fault in the wire, but to check to see if you need ventricular pacing. It's actually a very nice little safeguard that can overall save on the battery unless you are 100% paced. If so, like I am, you don't need to check to see if you need the right ventricular pacing, you DO need it.

Don't worry. Nothing is abnormal with your pacemaker at all. You probably have a muscle or nerve nearby when the voltage goes off and it gets stimulated.

I had been so scared when I first had this. Even my cardiologist wasn't aware of the impedance check. My EP was though. A click on the computer and it was gone!
Hope yours is as easy and I hope this helps.
Best to you, again,

Hi Gellia

by Wingart - 2007-12-13 05:12:43

Many thanks for that, like you I am 100% on the ventricals. I don't know as yet what percentage on the Atrium but from what I was told it will be about 50%. I hope that means they can turn it off, it does not hurt it is just an anoying reminder every 3 hours that I have a pm fitted.

I am comforted to hear that your wires have lasted so long. I was fully awake during the implant and the "trainee" who was performing the op had real difficulty getting in behind my clavical and caused me some real discomfort, I hope my wires last that long so that I do not have to go there again too soon.

One more question if I may?
I am 16 days post op (pm in left shoulder) and have just managed to get comfortable sleeping on my right side with the help of a pillow in front of me. The problem is depending how I lay I can feel every ping in the heart, again it is not painfull but disconcerting. Have you ever experienced this?

Thanks for taking the time to talk to me
Take care

Hi Chrissie,

by Gellia2 - 2007-12-13 11:12:22

If you are 100%, I think they can turn the check off. Reason being, it is to check and see if the ventricle needs pacing. 100% means you need pacing all the time so you don't need a feature to check to see if you do (have your dr call your pacemaker manufacturer if he has a problem with this). As for the "pinging". I used to think it was just a normal thing. I called it "my little man knocking to get out". Since I now go to an EP rather than just a cardiosurgeon, I no longer have it. All these years, the voltage was just too high! You may be able to get the voltage "tweaked" a bit so it is less noticeable. Be sure to mention it to your tech. or whomever will do your check up. Also, many times they wire needs to form a bit of scarring around it and that can help with your "little man", too. You feel the voltage. Make a list of these things and be sure you have them all addressed during your post op visit. I'm pretty sure they can help you with them all.
Good luck, Chrissie. If you want to email, just go to members and click on my name. You can send an email to my pacermail box.
Best to you!

You know you're wired when...

Your old device becomes a paper weight for your desk.

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A pacemaker suddenly quitting is no more likely to happen than you are to be struck by lightening.