a case for the trainees:

[caligas]

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56 yo male w hx or idiopathic cardiomyopathy (ef 30) presents for 2 level lumbar fusion. He has an ICD placed due to his cardiomyopathy and is closely followed by cardiology and has been cleared for surgery. He exercises daily. Ekg shows that he is paced @70 by the device and this is confirmed by the pre op monitors. No valve issues. No CAD. Airway looks fine. No other significant medical issues or lab abnormalities.

How do you proceed, specifically in regards to management of his ICD?

 

[anes]

Etom/sux/sufent/ tube/ magnet over pacer icd... Asynchronous mode, Zoll pads.

 

[caligas]

Etom/sux/sufent/ tube/ magnet over pacer icd... Asynchronous mode, Zoll pads.

pretty good. Any concerns about patient laying on the magnet?

 

[G0S2]

Magnet over pacer/ICD only disables ICD.

 

[anes]

Hence the Zoll pads. And hence switching to asynchronous mode. I would tape the magnet and place padding under it

 

[G0S2]

Magnet over pacer/ICD will only disable ICD. There will be no asynchronous mode.

 

[OB1🤙]

Hence the Zoll pads. And hence switching to asynchronous mode. I would tape the magnet and place padding under it

So you would interrogate the device to switch it to an asynchronous mode, leave the anantitachycardia function on, then disable it with a magnet taped to a prone patient's chest?

If I'm an oral board examiner, I'm not happy with this answer.

 

[Idiopathic]

i could see pitfalls with this approach

 

[BobBarker]

How about do nothing but have a magnet in the room?

 

[McPoyle]

I'm curious why we are wanting to disable the pacer? Does the patient not have the ability to compensate to the effects of our anesthetics by increasing his heart rate and thus we want total control over this?

 

[G0S2]

I'm curious why we are wanting to disable the pacer? Does the patient not have the ability to compensate to the effects of our anesthetics by increasing his heart rate and thus we want total control over this?

If you keep the ICD functioning, it may be affected by electrocautery and erroneously sense VT and zap.

 

[G0S2]

I'm curious why we are wanting to disable the pacer? Does the patient not have the ability to compensate to the effects of our anesthetics by increasing his heart rate and thus we want total control over this?

Sorry. You may be referring to just pacer.

 

[McPoyle]

I was, but that helps! Is this a concern anytime cautery is used or just when near the ICD?

 

[excalibur]

How about do nothing but have a magnet in the room?

2 part follow up question to your response:

A) What was your reasoning in coming up with this plan?

B) OK. Say you do nothing and have a magnet in room as you stated. What would be your determining factors in deciding if the magnet needed to be used intraoperatively and what results would you expect from the ICD if you were to use the magnet?

 

[BobBarker]

We had a lecture where an ep doc said not to do anything if working further than 6" away from the device. Magnet if I get scared by vt looking stuff on ECG during cautery to disable defibrillation.

 

[excalibur]

We had a lecture where an ep doc said not to do anything if working further than 6" away from the device. Magnet if I get scared by vt looking stuff on ECG during cautery to disable defibrillation.

OK. I agree the likelihood of electromagnetic interference (EMI) affecting the ICD is low given the distance away from the ICD, but your plan is to place magnet if VT looking stuff appears on ECG strip from cautery. I am certain too for a lumbar laminectomy, there will be VT looking stuff from the buzzing.

Well, couldn't the ICD fire from the VT looking stuff you see on the screen?? Again it's unlikely given the distance, but if it is worrying you, shouldn't the magnet have been on in the first place? Furthermore, is it going to be a piece of cake placing magnet in prone?

Follow up:

A) VT looking stuff appears all over the ECG during initial dissection and you do decide to sneak a magnet over the ICD. Later in the case the patient develops true Vfib. What would you do?

Follow up scenario 2

A) Does the EMI from the cautery bring any special concerns to you in regard to the pacemaker function on the ICD?

B) You elect to do nothing and place no magnet. During initial dissection, you see EMI on ECG. You then notice that HR on SpO2 is 30 and rhythm is irregular. What do you think is going on and what would you do?

 

[OB1🤙]

How have we gotten to the 17th post in this thread without anybody investigating what the 100% paced rhythm is all about?

 

[caligas]

How have we gotten to the 17th post in this thread without anybody investigating what the 100% paced rhythm is all about?

Further investigation of old EP notes reveals patient is dependant on the pacing function of the ICD due to complete heart block.

(I think there is more confusion and mis information on this topic than just about anything in anesthesia. The ASA guidelines are excellent for those who wish to fully understand the issue)

 

[excalibur]

How have we gotten to the 17th post in this thread without anybody investigating what the 100% paced rhythm is all about?

I would like to know to HB. Bottom line: his pump sucks. Too slow and too weak. But whether the 100% pacing is for 3rd degree AV block, or persistent symptomatic 1st or second degree AV block, my management for the ICD would be the same.

 

[BobBarker]

OK. I agree the likelihood of electromagnetic interference (EMI) affecting the ICD is low given the distance away from the ICD, but your plan is to place magnet if VT looking stuff appears on ECG strip from cautery. I am certain too for a lumbar laminectomy, there will be VT looking stuff from the buzzing.

Well, couldn't the ICD fire from the VT looking stuff you see on the screen?? Again it's unlikely given the distance, but if it is worrying you, shouldn't the magnet have been on in the first place? Furthermore, is it going to be a piece of cake placing magnet in prone?

Follow up:

A) VT looking stuff appears all over the ECG during initial dissection and you do decide to sneak a magnet over the ICD. Later in the case the patient develops true Vfib. What would you do?

Follow up scenario 2

A) Does the EMI from the cautery bring any special concerns to you in regard to the pacemaker function on the ICD?

B) You elect to do nothing and place no magnet. During initial dissection, you see EMI on ECG. You then notice that HR on SpO2 is 30 and rhythm is irregular. What do you think is going on and what would you do?

1. Take the magnet off.
2. A) Over and under sensing
B) tell surgeon to stop cauterizing. The pacer is oversensing and believes the cautery electrical signals are from the heart and isn't pacing. We can switch to bipolar cautery or attempt to have the pacer reprogrammed into asynchronous mode. Magnet will only disable defibrillation not put it in asynchronous as on a straight pacer. Probably you could finagle with the sensing programming but I wouldn't feel comfortable ordering the rep to do that.

 

[Arch Guillotti]

I'm curious why we are wanting to disable the pacer?

I don't think you can disable the pacer mode of an ICD.

 

[excalibur]

1. Take the magnet off.
2. A) Over and under sensing
B) tell surgeon to stop cauterizing. The pacer is oversensing and believes the cautery electrical signals are from the heart and isn't pacing. We can switch to bipolar cautery or attempt to have the pacer reprogrammed into asynchronous mode. Magnet will only disable defibrillation not put it in asynchronous as on a straight pacer. Probably you could finagle with the sensing programming but I wouldn't feel comfortable ordering the rep to do that.

1. You take the magnet off, and the AICD does not defibrillate. What do you do?

2B. I agree the pacer is sensing the EMI as intrinsic beats and is no longer pacing. You elected to do nothing for the patient preoperatively except to bring a magnet to the room, which you admit would not help in this possible scenario. So how would YOU switch the pacer function on the AICD to asynchronous mode in the middle of the prone case?

Extra 2B: You address the need for bipolar cautery with the surgeon and OR staff. This causes a minor delay. The surgeon asks you why the possible need for bipolar cautery was not addressed with him or the staff preoperatively. Your response?

 

[BobBarker]

1. External defibrillation. ACLS. Yes, flipping the patient and doing compressions whether the back is open or not if vfib not resolved by the external shock.

2. I wouldn't be able to do that. The device rep would have to be summoned but it is doable. Even prone. On our prone backs there is always room to reach where a device would be unless the dude is a whale.
2B. Because you would have been whining about using bipolar the entire case and this issue was unlikely to happen.

 

[excalibur]

1. External defibrillation. ACLS. Yes, flipping the patient and doing compressions whether the back is open or not if vfib not resolved by the external shock.

2. I wouldn't be able to do that. The device rep would have to be summoned but it is doable. Even prone. On our prone backs there is always room to reach where a device would be unless the dude is a whale.
2B. Because you would have been whining about using bipolar the entire case and this issue was unlikely to happen.

I like your last answer.

1. How long would it take for circulators to get the crash cart from the central core, open it, turn on the machine, plug in the cord for the Zoll pads and place Zoll pads on the patient in the prone patient? Or is the patient supine now? In initiating ACLS as you said, while waiting for the RN's to get the crash cart, would you and other staff members have already quickly flipped this patient onto his stretcher I guess and started chest compressions while waiting for defibrillation?

-Before the case started, were you 100% sure that the defibrillating mechanism on the AICD was functional? Had it even been tested upon initial placement of the AICD? If Zoll pads had been placed on the patient prior to induction and they were hooked up to the crash cart for the operation, couldn't you have defibrillated this patient immediately with the Zoll pads if the AICD did not defibrillate upon magnet removal?

2. You tell the surgeon to stop operating because his cautery is causing the pacer to malfunction. You summon the rep, and he says he will be there in 30 mins. The surgeon breaks scrub and leaves the OR. If Zoll pads had been placed on the patient prior to induction and hooked up to the crash cart for the operation, couldn't you have transcutaneously paced this patient immediately with the Zoll pads upon recognizing that the internal pacer was sensing the EMI as intrinsic beats and stopped pacing?

 

[excalibur]

I'm curious why we are wanting to disable the pacer? Does the patient not have the ability to compensate to the effects of our anesthetics by increasing his heart rate and thus we want total control over this?

Not trying to disable the pacer. Trying to program the pacer to asynchronous mode via the pacer rep. As stated in OP, this patient is pacer dependent. Every heart beat is generated by that pacemaker meaning the patient cannot generate a stable intrinsic rhythm at all. During surgery, electrocautery causes that classic static interference scribble on the ECG. Particularly with monopolar electrocautery, the internal pacer of the AICD may sense this interference as intrinsic heart beats and the pacer could be inhibited if it senses the interference as greater than 70 bpm (or whatever the pacer is set at). So what happens? The pacer shuts off, and this pacer dependent patient is in trouble as he is left with his crappy intrinsic heart rhythm, which in this case is complete heart block. By programming the pacer to asynchronous mode or VOO mode (not disabling the pacer), you are actually disabling the sensing function of the pacer and telling it to pace at its programmed rate irrespective of the patient's intrinsic rhythm, which for this patient is essentially nothing

 

[anes]

Yea... so like I said. magnet to disable ICD. Zoll Pads setup to take place of the ICD.
Place the pacer in asynchronous mode (rep)

So now there is no reason to worry about interference from cautery. The pacer will function regardless of outward influences.

Disable the ICD with magnet so no there is no worry about interference causing accidental discharge. If patient has life threatening arrythmia intra operatively, this will be taken care of by the zoll pads.

Afterwards, have rep re-interrogate the device to make sure its back to original settings.

Or am i WAAAAAAAY off base with that strategy? Would I be eaten alive by board examiners?

 

[OB1🤙]

What kind of pacemaker functionality do we have in this device? Single lead, dual chamber, maybe even biventricular? What are the current settings?

Has the ICD ever shocked him? If so, what is the history of antitachy therapy?

Residents- do the answers to these questions matter? Why or why not?

 

[caligas]

Yea... so like I said. magnet to disable ICD. Zoll Pads setup to take place of the ICD.
Place the pacer in asynchronous mode (rep)

So now there is no reason to worry about interference from cautery. The pacer will function regardless of outward influences.

Disable the ICD with magnet so no there is no worry about interference causing accidental discharge. If patient has life threatening arrythmia intra operatively, this will be taken care of by the zoll pads.

Afterwards, have rep re-interrogate the device to make sure its back to original settings.

Or am i WAAAAAAAY off base with that strategy? Would I be eaten alive by board examiners?

I think this is the best overall approach.

 

[caligas]

What kind of pacemaker functionality do we have in this device? Single lead, dual chamber, maybe even biventricular? What are the current settings?

Has the ICD ever shocked him? If so, what is the history of antitachy therapy?

Residents- do the answers to these questions matter? Why or why not?

Dual chamber icd, no hx of shocks. DDD.

 

[sevoflurane]

Disable the ICD with magnet so no there is no worry about interference causing accidental discharge. If patient has life threatening arrythmia intra operatively, this will be taken care of by the zoll pads.

Or remove the magnet if you can get to it (easier in the supine patient).

So what if the rep says... sorry, it's 2:30 am and we are not coming in to reprogram the pacer for your case becuse I'm 2 hours away. The case needs to go now.

 

[urge]

Yea... so like I said. magnet to disable ICD. Zoll Pads setup to take place of the ICD.
Place the pacer in asynchronous mode (rep)

So now there is no reason to worry about interference from cautery. The pacer will function regardless of outward influences.

Disable the ICD with magnet so no there is no worry about interference causing accidental discharge. If patient has life threatening arrythmia intra operatively, this will be taken care of by the zoll pads.

Afterwards, have rep re-interrogate the device to make sure its back to original settings.

Or am i WAAAAAAAY off base with that strategy? Would I be eaten alive by board examiners?

Your strategy will work. It is not very elegant, though.

It's like going to the grocery store for cigarettes and stopping at the gas station for milk.

Can you think of a more efficient way?

 

[urge]

We had a lecture where an ep doc said not to do anything if working further than 6" away from the device. Magnet if I get scared by vt looking stuff on ECG during cautery to disable defibrillation.

This would be my approach on a supine patient. But this patient is prone. I doubt I would be able to get a magnet in or out quickly enough.

 

[DrBeaker]

Yea... so like I said. magnet to disable ICD. Zoll Pads setup to take place of the ICD.
Place the pacer in asynchronous mode (rep)

So now there is no reason to worry about interference from cautery. The pacer will function regardless of outward influences.

Disable the ICD with magnet so no there is no worry about interference causing accidental discharge. If patient has life threatening arrythmia intra operatively, this will be taken care of by the zoll pads.

Afterwards, have rep re-interrogate the device to make sure its back to original settings.

Or am i WAAAAAAAY off base with that strategy? Would I be eaten alive by board examiners?

Where I'm training this is what we do. Magnets do different things to different devices. I wouldn't trust just using a magnet. As far as interrogation goes, if he is being shocked a lot, the defib function stays on until we are in the OR with pads on. Rep meets us in the OR and turns it off then. We also have a couple different machines in our Preop clinic to interrogate different AICD's and we are able to turn off the antitachy therapy ourself if no rep is available.

 

[OB1🤙]

Here's what I would do.

First of all, I really don't like the idea of going digging under the chest of a prone patient to put magnets on or take them off in the heat of a critical event, nor do I like the idea of the pressure of the magnet over the chest for the whole case. I want the rep to disable the antitachy therapy preop. This is an ICD placed for primary prevention, and if there is no history of arrhythmia, it is unlikely to happen during the surgery. However "unlikely" is not the same as "impossible," so we place the pads. IF there was a strong history of being shocked, I would consider doing the magnet thing so that I could remove it to let the device shock him internally if it came to it. I think it'd be important to make sure that removing the magnet actually re-enables the antitachy therapy. Have the rep confirm this.

With respect to the pacemaker. We have a dual chamber device, and we see pacing spikes with a rate of 70. It is entirely possible that this is a sinus rhythm at 70, with atrial sensing and ventricular pacing. We should find out. Is there one pacing spike or two? If only one spike, is there a p-wave before every spike?

It is also entirely possible that his native rhythms are slow or nonexistant, so that the device is set to a backup rate of 70, making it essentially a DOO device. He may even be in afib, with a device essentially functioning in VVI mode at a rate of 70.

Why does it matter? I want to know because if he's atrially tracking, then he goes about his life with his HR going up and down like the rest of us. And if he was to experience blood loss, his HR would normally go up to compensate.

If you just asynch him DOO at 70, you'll probably make it through the case OK, but I wouldn't say you were optimizing his hemodynamics, since you're marrying him to the rate he's in at rest. If I know I'm working with a sadistic butcher, I may have the rep bump the rate up to 80 or 85 preop, just to give me a little extra room on the cardiac output I have to work with if we do lose some volume. I'd probably figure out (by interrogating the device) what kind of rate he produces when he exerts himself, and aim for something in that range for the case.

This approach is probably less science and more art, but I think it's a more physiologically appropriate approach to the procedure.

 

[Scotty_G]

Would it be safe to pace him at a higher rate like 90ish so you don't risk a R on T phenomenon if his intrinsic HR goes above what you set the pacer to? I know in this case scenario you said the pt has 3rd degree HB so this is unlikely. What about other patients whom you do not know? At our institution we do what Drbeaker said: device gets interrogated in the OR preinduction and after pt wakes up (but before he leaves OR) What happens if you have emerg case at night and you cannot get a rep: use magnet and it has weak battery putting the pacer into asynchronous mode but at a slower HR leading to R on T phenomenon?!?!

 

[Idiopathic]

Would it be safe to pace him at a higher rate like 90ish so you don't risk a R on T phenomenon if his intrinsic HR goes above what you set the pacer to? I know in this case scenario you said the pt has 3rd degree HB so this is unlikely. What about other patients whom you do not know? At our institution we do what Drbeaker said: device gets interrogated in the OR preinduction and after pt wakes up (but before he leaves OR) What happens if you have emerg case at night and you cannot get a rep: use magnet and it has weak battery putting the pacer into asynchronous mode but at a slower HR leading to R on T phenomenon?!?!

just remember that a magnet on this device wont do anything to the mode of pacing. for emergencies you do what you have to do, also, interrogating before the leave the OR is terribly impractical (unless you mean PACU)

 

[ArMed]

Solid discussion. Just a few quick q's:
If the surgeon has bipolar available, whats the harm in using it?
If the Zoll's are available, whats the harm in placing them?
Why cant we take some preventative measure if using monopolar, ie; a larger pad at a caudal locale?
Also, if the pt is completely pacer-dependent,what's the harm in setting a higher-than-inherent asynchronous mode?

Still, I feel like the whole discussion is made moot by just using bipolar.

 

[sevoflurane]

Had a patient in complete heart block with AICD with a compromised RV lead this morning going in and out of asystole. See attached PDF for those interested in magnet use for Boston Scientific AICD's.

This is a good discussion indeed, and one you will encounter in practice. Remember, you as the anesthesiologist heads this ship at 2:00am when that thoracic case comes in with a pacer/aicd in the patient who has complete heart block and is dependent on it.

Different devices may respond differently to a magnet.

 

[Scotty_G]

All ICD's have pacemakers built in right?

 

[sevoflurane]

Right.

Except for the really, really old ones... which at this point are likely not around anymore.

 

[excalibur]

From last month's edition of Anasthesia and Analgesia:

"Use Caution When applying Magnets to Pacemakers or Defibrillaors for Surgery"
Peter M. schulman, MD and Marc A. Rozner, PhD, MD

http://www.anesthesia-analgesia.org/content/117/2/422.full.pdf

3 case reports of problems that were encountered when applying the magnet

 

[Idiopathic]

Solid discussion. Just a few quick q's:
If the surgeon has bipolar available, whats the harm in using it?
If the Zoll's are available, whats the harm in placing them?
Why cant we take some preventative measure if using monopolar, ie; a larger pad at a caudal locale?
Also, if the pt is completely pacer-dependent,what's the harm in setting a higher-than-inherent asynchronous mode?

Still, I feel like the whole discussion is made moot by just using bipolar.

1. bipolar cautery is not typically used for large dissections
2. around $600 a set
3. you can, but you will still run the risk that current will be dispersed near the pacer site and interpreted as cardiac activity - risking either failure to pace or attempted overdrive pacing
4. you can choose whatever rate you want, and if programming to asynchronous mode should probably set the rate a little higher - risks apply such as potential for myocardial ischemia and atrial fibrillation, etc. as they would for anyone with cardiomyopathy and higher heart rate. i would think that anything between 70-100 would be fine, however

 

[fakin' the funk]

56 yo male w hx or idiopathic cardiomyopathy (ef 30) presents for 2 level lumbar fusion. He has an ICD placed due to his cardiomyopathy and is closely followed by cardiology and has been cleared for surgery. He exercises daily. Ekg shows that he is paced @70 by the device and this is confirmed by the pre op monitors. No valve issues. No CAD. Airway looks fine. No other significant medical issues or lab abnormalities.

How do you proceed, specifically in regards to management of his ICD?

Had this exact case.

We did nothing to the device, given distance of unipolar cautery. Put Bovie return pad on leg. Made sure that chest rolls weren't covering the device itself.

Had magnet handy.

Surgeons Bovieing like crazy after incision and getting down to bone. No antitachycardia events.

During boring part of case, surgeon starts Bovieing again, pacer function starts to sense unipolar cautery and goes into pacemaker-mediated tachycardia! Put magnet on, secured with big Tegaderm, that fixed it, no issues thereafter, called EP to interrogate postop.

Moral of the story: it's not just inappropriate lack of pacing, or inappropriate shock, that you gotta be worried about.

 

[caligas]

Had this exact case.

We did nothing to the device, given distance of unipolar cautery. Put Bovie return pad on leg. Made sure that chest rolls weren't covering the device itself.

Had magnet handy.

Surgeons Bovieing like crazy after incision and getting down to bone. No antitachycardia events.

During boring part of case, surgeon starts Bovieing again, pacer function starts to sense unipolar cautery and goes into pacemaker-mediated tachycardia! Put magnet on, secured with big Tegaderm, that fixed it, no issues thereafter, called EP to interrogate postop.

Moral of the story: it's not just inappropriate lack of pacing, or inappropriate shock, that you gotta be worried about.

This seems like a good example of the need to convert to asynchronous mode pre op.

 

[TrustMe]

All ICD's have pacemakers built in right?

No.

I don't know exact reasons/indications.

Had dude in CTICU couple weeks ago. 50-something male, non-ischemic dilated cardiomyopathy, EF 20%, ICD for primary prevention, severe MR, TR. Had MV repair, TV repair, CABG x1. Developed complete heart block post-op. EP had to put in pacer leads as he only had ICD function. Actually upgraded to CRT-D, which surprisingly didn't help his recovery at all, neither did his anuric AKI requiring CVVH or his prolonged inotropic dependence.

 

[caligas]

No.

I don't know exact reasons/indications.

Had dude in CTICU couple weeks ago. 50-something male, non-ischemic dilated cardiomyopathy, EF 20%, ICD for primary prevention, severe MR, TR. Had MV repair, TV repair, CABG x1. Developed complete heart block post-op. EP had to put in pacer leads as he only had ICD function. Actually upgraded to CRT-D, which surprisingly didn't help his recovery at all, neither did his anuric AKI requiring CVVH or his prolonged inotropic dependence.

That is unusual, maybe on older device? My understanding is that all modern icds have pacing capability.

 

[DrBeaker]

All current ICD's have the ability to also pace. Must have been an older ICD.

 

[TrustMe]

That is unusual, maybe on older device? My understanding is that all modern icds have pacing capability.

I initially thought the same thing. I should have talked with the EP guy some more. Pt was several days post-op when I came on service and EP was already seeing him so I didn't get in on the initial conversation. He may have had a single V-lead with pacing capability but they thought that he would do better with dual chamber/CRT-D pacing? Don't know.