placing atrial epicardial wire into ventricular port of pacer

ZASHAGALKA, RN · Dec 14, 2006

Does anyone have experience with placing an atrial pacing wire into the ventricular port of a pacer in order to increase the available output? Is there anything special we need to know about the rest of the settings after doing this? i.e. the pacer is now sensing the atrial activity I believe, but it "thinks" it's ventricular, is there a possibilty of inappropriate firing???

I would say, at first glance, that the main issue would be if the leads were 'cross threaded' meaning that BOTH the atrial and ventricular leads were reversed and THEN, only if the pacer is in mode to correlate the two signals. So, as far as precautions, I would make sure that the atrial side of the pacemaker is turned down to no output (because, you should only be using the ventricular side of the pacer for this).

If you purposely inserted atrial wires into the ventricular pacing chambers, then, theoretically, you are using a only a 'ventricular' mode to stimulate the atria, if that makes sense. Why I say that is you are doing this for one of 2 reasons, most likely: 1. decreased overall sensativity, in which case, you would not want relatively more power to the atria, but less to the ventricals, in any case, or 2. you have some output problem with the atrial wires themselves, which means that you are shunting 'power' based on the knowledge that some defect prevents correlated pacing to start with.

I would say that this is an attempt, it seems, to circumvent the capacity of the temporary pacer in general and ANY time you circumvent manufacturer specs, you create a risk to have to legally justify such a decision. That means, documentation is of paramount importance.

Also, TEMPORARY means just that: if you are not getting the desired performance from temporary wires, the 'fix' is a more permanent solution. This sounds like someone that needs a permanent pacer, and soon.

Now, this is just thinking off the top of my head, and I'm certainly open to other intepretations.

~faith,

Timothy.

graciev · Dec 14, 2006

The reason that I submitted this questiton is because post open heart surgery we have quite a few instances where the atrial wires will just not work and the CT docs often have us try switching the atrial wires to the ventricular output port of the box in attempt to use a higer Ma and obtain capture. So I wonder if this is safe. The patient frequently needs pacing for only a short time so permanent pacing is not an option.

ZASHAGALKA, RN · Dec 14, 2006

The reason that I submitted this questiton is because post open heart surgery we have quite a few instances where the atrial wires will just not work and the CT docs often have us try switching the atrial wires to the ventricular output port of the box in attempt to use a higer Ma and obtain capture. So I wonder if this is safe. The patient frequently needs pacing for only a short time so permanent pacing is not an option.

Correct, those flimsy wires are garbage. But, as I said, IF that is the reason, then 'cross-threading' the wires (feeding both sets of wires into their opposing sides of the pacer: atrial to ventrical AND ventrical to atrial) is not at option as you already know you don't have the capability to pace both sets of wires under normal operation.

Is it safe? It's using a device against manufacturer's specs, so you are right to be on higher alert to such dangers. Ultimately, I'd say that IF you can get capture by doing this when you couldn't the other way, then it's 'safer' then no capture at all, yes? And if permanent pacing isn't an option, in a pinch, if you can't get capture, you have to move to inserting transvenous wires. No matter HOW temporary you need them, if you need them, you need them. (Of course, since you are more interested in just atrial pacing, meds might be of help for rate control instead of being more aggressive with pacing if the wires won't work.)

Ultimately, this is an attempt to avoid a more invasive intervention. That is pure risk/benefit. Is the risk of using the ventricular side of the pacer for atrial wires greater then having to set up and insert new transvenous wires (or adding more and possibly competing meds to the mix)? I'd say probably not, it's a risk worth trying.

But, I document the heck out of it. And, I'd make sure that only the atrial wires are connected and that the 'atrial' side of the pacer, now not being used, is turned all the way down (or the mode you set is a pure 'ventricular' mode) as you are only using the ventrical side of the pacer to pace the atrial wires.

~faith,

Timothy.

Dinith88 · Dec 15, 2006

I'd like to add, though, that if you're using the 'v' settings to pace the 'a' lead...then you should probably disconnect (rather than simply turning down) the other wire because the pacer could then be working 'backwards' and could potentially cause (lethal?) arrhythmias with this possible 'retrograde' pacing.

Another thing...if you're using the 'v' lead/output to pace the atria, you will lose the 'rescue' capability of the pacemaker. If, for example, your patient goes into a block, or (worse) an asystolic arrest, you simply wont be able to pace the ventricles out of it...because the ventricular outputs/settings are occupied trying to pace the atria instead (which would be of no benefit in a block...or in p-wave asysytole, etc.). Also, Pacing the 'a' with the 'v' settings would ONLY be of benefit if patient were capable of being atrial paced...(ie a-fib cant be atrial paced...etc.).

I've never done it...and would have serious reservations...

graciev · Dec 15, 2006

One of the questions I have, is if the atrial wire is placed into the V port of the pacer, the the only electrical activity being sensed would be from the atrium. To program the pacer, then, because you are using the ventricular settings, you would put the pacer into VVI??? And then get the equivalent of AAI?????? What would happen if you put it in DDD (which is what the docs say to do).

Sorry for being soo confused.....:uhoh21:

Grace V

Dinith88 · Dec 15, 2006

And then get the equivalent of AAI?????? What would happen if you put it in DDD (which is what the docs say to do)...:uhoh21:
Grace V

Hmmm. I wish i could pick this doc's brain.

Ok...lets assume you're in 'ddd' with the leads switched....and the patient is in a marked sinus bradycardia...(and both leads are 'capturing')

the 'a'-lead fires first...and captures the ventricle (which depolarizes/contracts.) the second thing to happen would be the 'v'lead fires ...and captures/depolarizes the atri. This is backwards...so..your ventricles eject their load, and the atria try ( fraction of a secod later)to dump theirs into the ventricle (which is already depolarized/contracted). At best, you would induce (in essence) a junctional rhythm and be losing your 'atrial-kick' (so whats the point in ddd???)...and at worst you'd induce a bad regurgitation/chf/etc... The idea of DDD with the leads switched sounds like very bad (nonsensical) practice. With the leads backwards, i can only envision atrial pacing being possible...(and why would you SWITCH leads and put in DDD if only ONE set of wires is working???? kinda sounds silly...both leads need to function properly for DDD-mode). AND, as i've said, if only atrial pacing (with the v-lead) you lose the 'rescue' capabilities of the pacer.

BUT..i'm wrong alot...so maybe this is acceptable???

I have access to a number of cv-surgeons and ep-docs...and now that i'm curious i'm going to ask them their opinion about this...

live_crow · Dec 15, 2006

We do it all the time when unable to atrially pace (our surgeons prefer AAI pacing in most postop CABG as they are only trying to maximize rate and output). We disconnect the ventricular leads, attach the atrial leads to the "v" port of the pulse generator, crank up the output. It works fine, and the pacing is usually off by POD 1.

Note: We get our docs to write this procedure as an order so we are covered. We LABEL CAREFULLY on the pulse generator that they are atrial wires and also document this in the notes.

graciev · Dec 16, 2006

Guess I should clarify, they request the DDD mode with just the atrial wire in the v port, I think they think that somehow the lone wire in the atrium is sensing the atrial and ventricular activity. Have never been able to figure this out, and can't really get it to work anyway...............................

Dinith88 · Dec 16, 2006

Guess I should clarify, they request the DDD mode with just the atrial wire in the v port, I think they think that somehow the lone wire in the atrium is sensing the atrial and ventricular activity. Have never been able to figure this out, and can't really get it to work anyway...............................

OK...now it's obvious that the doctor who orders this is way wrong. In order to 'sense' and 'pace' the ventricle a wire needs to be physically on/in/touching the ventricle. If the wire that is doing so is 'bad' and/or not plugged in to the pacer you're unable to do so. DDD is useless in this scenario. As you say, the only thing that would half-way make any type of far-fetched sense is the pacer set to VVI (which would be theoretically giving you an AAI pacemaker)... ??? strange.

That guy needs to go back to meds-school and re-read his cardiology stuff.

live_crow · Dec 16, 2006

Guess I should clarify, they request the DDD mode with just the atrial wire in the v port, I think they think that somehow the lone wire in the atrium is sensing the atrial and ventricular activity. Have never been able to figure this out, and can't really get it to work anyway...............................

OK, then they are just wrong. Can you ask why DDD mode and explain it can't sense OR pace when there is no ventricular wire in place? May just be that they are used to seeing DDD and so say that all the time. Someone prescribing pacing treatment should really have an understanding of the modes of pacing.

SEOBowhntr · Jan 30, 2007

Does anyone have experience with placing an atrial pacing wire into the ventricular port of a pacer in order to increase the available output? Is there anything special we need to know about the rest of the settings after doing this? i.e. the pacer is now sensing the atrial activity I believe, but it "thinks" it's ventricular, is there a possibilty of inappropriate firing???

If the doc wanted you to do this, he needs to be getting a cardiologist in to place a permanent pacer, PERIOD, plain and simple. If you need that much output, that pacing wire ain't gonna last long anyhow. Now in lieu of placing a permanent pacer, I HAVE SEEN atrial pacing done via a Transvenous pacer, but only on a couple of rare occasions. As far as "Can you do it?" Yes, but you can only pace in AAI mode or Asynchronous atrial pacing, and you have to keep in mind that the pacer WILL NOT have the capabilities of pacing the ventrical if it is arranged this way!!!!

I'd like to add, though, that if you're using the 'v' settings to pace the 'a' lead...then you should probably disconnect (rather than simply turning down) the other wire because the pacer could then be working 'backwards' and could potentially cause (lethal?) arrhythmias with this possible 'retrograde' pacing.
Another thing...if you're using the 'v' lead/output to pace the atria, you will lose the 'rescue' capability of the pacemaker. If, for example, your patient goes into a block, or (worse) an asystolic arrest, you simply wont be able to pace the ventricles out of it...because the ventricular outputs/settings are occupied trying to pace the atria instead (which would be of no benefit in a block...or in p-wave asysytole, etc.). Also, Pacing the 'a' with the 'v' settings would ONLY be of benefit if patient were capable of being atrial paced...(ie a-fib cant be atrial paced...etc.).
I've never done it...and would have serious reservations...

The bolded parts are partially incorrect, as I've seen numerous errors where nurses had pacemakers set up wrong, and FORTUNATELY no fatal arrhythmias resulted.

As to Atrial pacing A-fib, I've done it, and can show you patients who lacked Atrial Kick that benefitted as much as 25-30mm of Hg on their SBP once they were provided some atrial kick. Pacing a fibrillating Atria can be accomplished by adjusting the sensitivity so that the pacer is blinded to the fibrillation, most of the time with and epicardial pacer, that setting is less than 2.0 mV, then the pacer, not unlike a defibrillator, is "shocking" the atrial even as they fibrillate. This can be accomplished while DDD pacing, but in essence, you will be asynchronosly pacing the Atria. But this can only be accomplished with patients with slow A-fib, not A-fib w/ RVR. Difficult to explain, but I teach a class on it, and with the pacer in your hand, and showing how to do it, it's not as difficult as it sounds. This is an old trick I learned about 9-10 yrs ago from an ARMY CT Surgeon, and I've actually shown other doctors how to do it and that it works, but there is only a rare situation in which it is even a possibility of doing.