Question about ICD/pacemaker

[AnnieOaklyRN, BSN, RN, EMT-P]

Hi all,

I just had a question. Do some physicians set an ICD/Pacemaker to do overdrive pacing in the event ventricular tachycardia occurs in an attempt to avoid an ICD shock?

I had a patient with an extensive cardiac history , to include previous cardiac arrest, call because his ICD had fired x 3.

While caring for him we of course put him on our cardiac monitor which revealed a sinus rhythm with intermittent paced rhythm, but he was also having very frequent runs of VTach which were lasting

I noticed on some of the strips where the Vtach lasted longer the morphology of the QRS changed and there were what appeared to be pacer spikes clearly in the Rwave. My theory is that this was over drive pacing, but I am wondering if this could have also been a the ICD synchronizing and getting ready to shock, but I had never heard of that being visible on an EKG, is it?

The spikes showed up for the last 6 or so beats before the rhythm converted back to sinus and the patient said he did not feel a shock.

So, I am just wondering if its possible his doctor set the pacemaker to try overdrive pacing first before the ICD would be triggered to deliver a shock?

It was an interesting case. We did hang 150 mg of Amiodarone and he was still having runs of Vtach, but they were becoming shorter at least.

He also had 9/10 chest pressure not relieved by NTG. I was only able to capture one good 12 lead with some normal sinus in it which showed no changes for ACS (no elevation or depression). My feeling is he was probably having a Non STEMI, but only the labs will tell. I have not had a chance to do follow up.

I tried to upload a picture of the strip, but the site will not let me.

Annie

[AnnieOaklyRN, BSN, RN, EMT-P]

error

[MunoRN, RN]

I rarely if ever see ICD's that aren't programmed to first attempt override pacing. It's far more comfortable for the patient and uses far less of the generator's energy supply. I suppose if it's known for sure that override pacing will never be effective then it might make sense to just skip that step, but for most it's an attempt to avoid a shock that may not be necessary.

[asjsmall]

. I just had a question. Do some physicians set an ICD/Pacemaker to do overdrive pacing in the event ventricular tachycardia occurs in an attempt to avoid an ICD shock?

Yes. It's called ATP. AntiTachycardia Pacing. It's used to prevent shocks and works well for VT. how the device is programmed will determine how many rounds of ATP the device will give prior to shocking. Slower VT episodes are usually programmed for more rounds of ATP before shocking than faster VT episodes as they are usually less symptomatic and have a lesser incidence of syncope thus allowing more time to reduce the possibility of a shock. Some devices are also programmed to give 1 round ATP while charging for shock (usually for VF or really fast VT). If the ATP while charging works the shock is never delivered. If it doesn't work no harm done because there was no delay in shock treatment. The goal is to only shock if absolutely necessary, as in the long term shocks can increase mortality.

[canned_bread]

Yes - we often set the defib to attempt to pace the VT out prior to the shock. The defib records the rhythm - ascertains its rate and type (VT and under 200 bpm say) and then if that fits the criteria of pacing set by the Dr, it will pace it out. If it is to fast or a VF then it may have criteria to shock instead. It also will only pace and then stop maybe twice and then will shock as backup.

The "looking" for R waves is not visible, as no electrical activity is outputted at this time, it's simply read.

Very impressed that you saw it and thought of different things it could be - good thinking!

[DogLover17]

Almost all ICD's I've seen will ATP pace before. We had a guy come in in VT storm and it would ATP pace x 10 (!!!) before shocking. (His request--Had some serious PTSD from ICD shocks and eventually had the ICD turned off completely.)

[Mavrick, BSN, RN]

Now THIS is a high quality All Nurses thread.

Thanks for the clear presentation, helpful acknowledgements and learning opportunity.

win - win - win

[JustKeepSmiling, ADN, BSN, RN]

Excellent question and excellent answers!!

I wish more nurses wanted to understand pacer/ICD mechanisms. ATP pacing can be very beneficial.

The manufacturers have awesome free clinical resources on their website. one of them better than the others but I believe TOS may prevent me from seeing this as a form of advertising??

[MsBruiser]

Beyond programmed ATP therapies, a skilled pacemaker RN or Electrophysiologist can do manual overdrive pacing. It is pretty nerve racking and I always carry a calculator in my pocket so I can do rapid VT cycle length calculations. There is always the risk that ATP or manual overdrive pacing can be pro arrhythmic and put a patient into VF. In that case, we just shock them back to Sinus. "Just" shock them. Check out Medtronic University. Excellent free resource. The only way to learn pacemakers is to go to manufacturer websites, so that is hardly a TOS violation.