reply to Inga

Thank-you Inga for your comments. You seem to be very knowledgeable about Pacemakers. What is the difference between unipolar and a bipolar setting? I would appreciate your input. Kat

2 Comments

Bipolar - Unipolar

by SMITTY - 2009-12-23 04:12:42


Hi Kathy,

While waiting for Inga's educated answer on bipolar and unipolar settings on our pacemaker, I'll give my uneducated guess.

First I'm sure you know every electrical circuit must have two electrical conductors. Take for example your lamps, or any electric light where you can see the cord, it has two wires to complete the circuit. In this case that lamp can be considered bipolar. Now, if that lamp had only one wire and was sitting on some surface that could serve as the second (or ground) wire I would call it unipolar.

In the case of your pacemaker one lead serves the same purpose as that lamp's two wires to complete the circuit, to me it is in bipolar mode. (Google definition - an implanted cardiac pacemaker in which the lead contains both electrodes, anode and cathode, and is thus a complete circuit.)

Now if that pacemaker did not use that lead to complete the circuit and let the electrical conductive ability of our body to serve the purpose of the other wire, I would say it is in unipolar mode. (Google definition - unipolar pacemaker an implanted pacemaker in which the lead has a single stimulating electrode, the cathode, with the anode connected to an indifferent electrode, usually the outer surface of the pulse generator.)

Now, I just learned something new. This is one of those things I think I understand what they are talking about when I hear it, but I now know I have a very hard time passing my understanding on to others. I'm sure Inga can do better.

Smitty

I try...

by golden_snitch - 2009-12-24 06:12:04

Hi Kat!

Oh well, I'm really not that good in explaining the purely technical stuff, that's usually Frank's job (@ Frank: help!). Also, since English is not my mother tongue, it's a little more complicated for me. But I'll try, just like Smitty did.

The difference between unipolar and bipolar is, as I understand it, that in a unipolar setting the stimulus is travelling from the surface of the generator to the tip of the lead (that makes the circuit) and because it has such a "long way" it is at greater risk for interferences. In a bipolar setting the stimulus is only travelling between the anode and cathode both of which are in the pacer lead tip.

Nowadays, pacers are usually programmed to bipolar, the unipolar setting is chosen when the lead is not working well (for example when the isolation is damaged).

I have had my left ventricular lead set at unipolar in the beginning - don't really know why - but I was having problems with diaphragmatic pacing. The EP changed the setting to bipolar, and the problem was solved.

Hope this helps a bit.
Best wishes,
Inga

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