Loose Lead

Hello all -

I just had my 6 week pacemaker check up, which unfortunately showed a very high voltage requirement (5 volts) for the ventrical lead. The cardiologist said to have it checked again in one month, and if it this isn’t improved substantially, the lead will need to be re-attached.

So questions:

1. What is the likelihood of a substantial lowering of the voltage improvement after already being in place for 6 weeks?

2. What could have caused this? I went beyond the restriction advice in every way in an attempt to avoid just this situation.

3. The Pacer lab tech that ran the test said this would be pretty much a redo of the original installation, just one of the leads is good already....Uugh! Is that the case?...haven’t got word from the cardiologist on this yet.

Thanks, and regards,

Larry

6 Comments

Voltage Increase

by SMITTY - 2011-07-27 11:07:50


Hi Larry,

I will make a few guesses on your questions.

I think the probability of a voltage reduction occurring on its own is pretty slim.

A voltage increase requirement after a lead has been in for months or years could be because of a damaged lead or a buildup of scar tissue at the point of contact with the heart's wall does happen. But such increase so soon after the implant makes me think the lead is not making good contact with the heart's wall or again, it could be damaged.

A damaged lead does not necessarily mean it is anything you have done. For example if the lead insulation was damaged when it was implanted or it the lead is not making good contact at the pacemaker terminal could cause an increase voltage requirement. Those leads are just like any other electrical connection we are familiar with, except these are much more delicate.

I have not had a problem with my leads that are now 11 years old. I did have to get a PM replacement a couple of years ago and my leads were good. As for what you must have done, I think it is like the tech said to a degree. The Dr will have to open up the PM pocket so that he can access the PM and the leads. If the problem is due to poor contact with the heart wall there is a slim possibility of it can be attached to the heart as was intended at the start. If the lead is damaged it will have to be removed and with it being is for short time, from what I have heard people say that will be more like just sliding out that lead and putting in another. If the other lead is still good it will probably be left in place. You probably will have to go through the same restrictions you went through when you got the PM.

In case you wonder how leads are made to stay in contact with the heart's wall, two different type tips are used. One is like a cork screw and the lead is literally screwed into the wall. The other type uses a barb like on a fish hook to make the attachment to the heart wall. Why the two different types are used I do not know.

Good luck,

Smitty

I agree with Smitty

by ElectricFrank - 2011-07-28 01:07:11

The only thing I would add is that the situation is very unlikely to improve by waiting. If the lead is not making good contact, or is located in unresponsive tissue it isn't going to get better by itself.

I can't back it up, but have often felt that the "wait and see" approach is to get past the time where an insurance company expects a problem to be corrected as part of a "warranty" situation. If they can delay past that time it is considered a new procedure and will be pain for.

Just a guess.

frank

Tech help

by dezineit - 2011-07-29 09:07:56

Leads generally take 6 weeks +/- to "heal" into place. Given the fact that you are right at that boundary, I would suggest that the lead has incurred either a micro or partial dislodgement. This would have to be weighed against the measurments at implant to note the change. What was the original voltage output? The current is what is important. This is generally a static number. When a lead move it is the impedance (resistance that changes. For example, an output of 2 v at 500 ohms yields a current of 4.0 mA. If the resistance increases to 800 ohms the resulting current would be reduced to 2.5 mAmps. So in order to make up for the current differential, all that can be done without physically moving the lead into place again would ne to increase the voltage output. By the way, the voltage output would have to be increased to 3.2 v in the above scenario to acchieve the original 4.0 mA value. This is nothing more than use of Ohm's law- current=voltage/impedance.

Hope this is helpful!

One more detail

by ElectricFrank - 2011-07-30 01:07:07

I agree totally on the calculations. There is one gotcha with increasing the the voltage to handle a dislodged lead. A properly attached lead applies the total current to a very small area of the the heart wall. A dislodged lead spreads the current over a wider (and variable if it is flopping around) area of the heart. This results in a lower current density. Since the hearts response is threshold based it may take even more lead current to reach threshold.

The other factor is that in order to get the current to move away from the lead tip into the heart they usually need to change to unipolar mode. Otherwise, a substantial part of the current short circuits through the blood and returns via the outer shield of the lead.

By the way I've found most cardiologists and even some EP's have no understanding of this. It's one of the reasons that the manufacturers rep is a better choice if there is a problem.

frank

update

by flgraminator - 2011-09-12 08:09:04

I went the pacer lab today 2 weeks after implant and the voltage was 3 or 4. The lab tech said that the original reading was .6 and was concerned about the increase. I have tried not to raise my arm.
Did you get any update as to why this has happened to you?
I hope you are well
Madeline

Madeline....

by cbchrome - 2011-09-16 11:09:28

About the only answer I get is that "it just happens" in about 1% of the cases.

I had my lead repositioned two days ago and the voltage is 0.5 (again), but I'm sweating it out to the next lab tests.

Regardless of what they've told me about this probably not being due to something I did, I'm trying to really avoid sudden movements (tougher than it seems) and contracting my upper chest muscles (like when getting up from bed). I'll try to avoid driving early on as much as I did the first time around as well. These are my adaptations keep in mind though. I just can't see doing things the same as the first time, and just hopeing for a better result.....which seems to be what I'm hearing from the doctors and technicians.

Good luck to you as well......

Regards, Larry

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