Help needed understanding lead readings...

Hi

So I have a quick question about atrial lead (select secure)...not because I am concerned but more because I just don't understand it and I want to.

So my readings 3-4 months ago were:

Sensing: 3.10v
Impedance: 1001Ω (B)
Threshold: 0.60v @ 0.40ms (B)

In the last couple of weeks:

Sensing: 3.50v
Impedance: 933Ω (B)
Threshold: 0.50v @ 0.40ms (B)

What do these numbers mean?? Can anyone explain - also what affects them changing?

Be good to understand...naturally curious!

Thanks

x

2 Comments

symbol next to Impedance

by FighterGirlxx - 2015-05-04 02:05:32

This should be the Greek Omega symbol...copy and paste didn't work

Hi FighterG

by IAN MC - 2015-05-04 04:05:09

First of all , the readings you list are all within normal range. If they weren't they would have looked very concerned, jumped up and down and altered the settings or even worse.

I'm no expert but I'll have a go :_

SENSING is a measure of the minimum sized signal which your PM is programmed to pay attention to.

Your PM is continually being bombarded by electrical signals both internally from your muscles contracting etc and externally from your TV . cell phone etc . If the PM didn't have a minimum sensing setting it would interpret all of these signals as heart-beats. So in your case your PM only reacts to electrical signals above 3.50v ( or is it milli volts, I can't remember )

IMPEDANCE Can be loosely described as how " difficult " it is for an electrical signal to be sent or received by the PM.

The electricity produced and received by your PM has to travel through the leads and through human tissue. It meets varying levels of resistance on the way and that is known as impedance.

It is a very important measurement because if it is too low it may mean that insulation around the lead has split; if it is too high it may mean that a lead has fractured or it is separating from the heart tissue. Impedance also alters when you exercise. It does alter slightly every time you have your PM checked so nothing to worry about.

THRESHOLD This is the minimum amount of electrical energy that your PM can apply to the heart and still trigger a heart-beat. In your case, your PM needs to deliver at least 0.5 volts of electricity over 0.4 milli seconds to make your heart beat.

The noticeable effects on you of the tiny changes you have seen in your readings will be zero !

Cheers

Ian

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