Bipolar vs unipolar

Hi all,
My recent pacer implant called for some changes to be made to try and get more battery life so lead/current were changed from unipolar to bipolar. My first check showed episodes of v tach. My ep was afraid my heart did not like the configuration so he changed it back to unipolar. I am not feeling any better but think it may be related to rate response levels. I believe it is set to low.

My question is this, has anyone experienced this change and if so did they have any problems with it? I would like to stick with the bipolar to save a little battery life. Does anyone know why this setting would cause v tach? Would it cause any other problems?

Susan

3 Comments

?polar

by ElectricFrank - 2012-05-23 02:05:39

The difference is in the way the pacing current is injected into the heart. With bipolar the return circuit is through the leads which is more efficient. I wonder why it was set to unipolar in the first place. It is rarely used except for a temporary way to handle a bad lead wire. Too often a tech will go on a "fishing expedition" and try switching modes to see if it helps.

There is one other way it can be set to unipolar. If the pacemaker senses a lead problem that is interfering with pacing it may switch to unipolar automatically.

I suppose it is possible that bipolar could be related to the ftach, but generally the bipolar is better since it localizes the pacing current to a smaller area of the heart. Since you are still having problems after resetting to uni I doubt it was related.

My suggestion is to request a copy of the pre and post checkup report at your next session. It would be interesting to see what settings and data it shows.

frank

Frank

by Shortcake - 2012-05-23 08:05:12

Hi Frank,
Thanks for the info. I am wondering if this could be part of my problem. Several years ago and 5 pacers ago, I had a break in a sheath and was being electrocuted. They fixed this while changing the pm. However since, each of my pacers are lasting about a month less than the one before. I am now down to 7 months between changes. My ep was telling me it is because of the high voltage and the fact that I have 4 leads. He says it is "baking" the wires and causing the drain on the pacer. I had to have all my leads changed years ago because a sponge was left in the pacer site....major infection to say the least. He and I both frowned at his comment and said we didn't want to talk about changing leads. Not yet any way. I went back over my printouts and it appears they did the polar shift back when the lead had the break. I am wondering if I should ask about this, since they swore to me it was fixed from the break. My question is simply, would a sheath break that was supposedly repaired be considered a bad lead (requiring the unipolar setting) or could it be because it was the beginning of the leads being fried from the high current? just to let you know, no one other than my ep is allowed to change my settings. We had such a time with everyone wanting to turn things down now my file comes up with a big red flag that says "Make NO changes". I get really sick when my settings are lowered.

I have an appointment on Friday to adjust my RR, I'm not getting enough speed when I am moving about and feel really lousy. They are hoping this will fix this bad feeling.

I have never had a pacer last over a year so I am wondering why they would change it to use more battery life in the unipolar mode and now that it's not lasting they changed it back to bipolar.

Would love to know your thoughts. Thanks for your help!
Susan

Hmmm

by ElectricFrank - 2012-05-24 01:05:26

I'm having an uneasy feeling about the stories the EP is telling you. There is no way that the energy of a pacemaker even with 4 leads could "bake" the leads. That is pure balderdash. Put together leaving a sponge in the pacer site, running a pacer on unipolar for years, telling you ridiculous stories, etc. and I would be looking for another EP.

One possibility is to ask for an appointment with a Medtronics rep. They should be able to determine the condition of each lead from the voltage/impedance data during a checkup. (so could the EP, but...).

You are going to be living with the pacemaker for many years so it is worth getting it straightened out.

frank

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