Pacer question

[monkeyman1000]

Allright, I'm a relatively new nurse (2 yrs) and I have spent the whole time on Med/Surg and Trauma/Surg ICU's, no cardiac experience. I've had a patient off and on for the past 4 weeks who came in for cholecystitis with a resulting non ST elevated MI. He had a previous history of A fib and has a pacemaker. He kept going into V-tach requiring a total of 4 cardioversions over the period of a week along with being on an amio drip, esmolol drip, lidocaine drip, levophed drip as well as a heparin (he had a stent placed in the LAD this admission along with a cholecystectomy), versed, morphine and brief vec drip also. Initially his ECG showed atrial pacer spikes without venticular pacer spikes. Then later in the week he showed no p wave or atrial pacer spikes but a ventricular paced rhythm with a wide complex. Then yesterday I came back and he has a Atrial paced beat only with a rate anywhere from 83-120 (all with the atrial spikes). The last note from the cardiologist that I could make out said his pacer had been set at a DDD function. The cardiologist I spoke to said DDDR. One nurse told me that pacemakers can be set so that they will do all the normal stuff then in the case of afib they will run at a higher rate to try and "overrun" the afib rate. The cardiologist told me that the pacer was set so that if it felt that the patient was being more active (sensing the movement of the pectoralis muscle) that it would increase it's rate to match the patient's activity level. First question is what in the hellfire and brimstone? Next question has anybody seen anything like this? (I also saw that an EMG specialist came in during the vtach episodes and made some changes on the pacer but the note didn't say much other than a recommendation that the patient get an ICD when he is more stable). Basically I'm not sure what to think. The guy made me totally nervous. At one point during the v paced episode one of the older nurses (experienced I mean) started saying that the guy may be getting refractory(?) to the meds, ie that he had been on the amio drip for about 6 days at 1mg/hr and might not be responding anymore. I'm confused.:monkeydance:

[papawjohn]

Hey Monkeyman!!!

It's been so long since I did CCU!! I have spent years (decades!) on MedSurg ICU and Trauma. But let me try to answer a few of your questions as best as I can.

You know of course that the DDD means it senses and paces in both atrium and venticle. So if the pacer is doing all it's s'posed to do, and no spontaneous beats are occurring, what you would have on the monitor would be the smaller pacer-spike--followed by a P-Wave--followed by a pause--followed by another (bigger) pacer-spike--followed by a wide-complex QRS.

Now what happens if he goes into Atrail Fib? Obviouslly the Atrial SENSING lead gets stimulated often enough to stop the atrial pacer from firing. So the Ventricular SENSING lead is waiting for an electron or two to show intrinsic activity and (failing to sense a ventricular beat) will Pace the ventricles.

Now modern pacers have the 'over-drive' and variable-rate features you described. And I don't know how they do that. Hope someone will educate us both.

But seeing only atrial-paced beats followed by a 'normal' QRS instead of a paced beat, or only Ventricular beats, seems reasonable to me.

Did the cardiology people 'interrogate' the pacer? That's usually done by the manufacturors representative and a report left in the Progress notes.

Hope that helps

Papaw John

[monkeyman1000]

Thanks for the reply. No I didn't see anything like that in the progress notes but a rumor that the pacer settings had been changed during all this was somewhat passed on in report. I think that at the end of this year I'm going to switch to a CVICU/CCU (what's the difference?) to learn some of this stuff. Cardiac stuff scares me which tells me I need to just do it.

[LCRN]

I'm at a loss about the pacer beside mode could've been changed or augmented by being interrogated. About the senior RN referring to being refractory to the meds...to be on 1mg/min of amio for more than the usual 6-8 hours (then you're to reduce the dosage in 1/2) can cause amio toxicity. Have you guys been running labs on this patient?

[monkeyman1000]

No I didn't see any labs at that time regarding amiodarone. The standing orders in the chart normally for amio are what you said but the cardio specifically stated to keep him at that rate. Doesn't amio cause fibrosis? Anyway I saw the pt today and he's doing sort of better, cardiac issues are stable and they're trying to wean him off the vent. Thanks again for the replies.

[theonlychances]

hey....im a new nurse...but I have a good link to direct you to...

go to nursingceu.com....click under pacemakers...there is an excellent discussion there regarding pacemaker classification, interrogation, troubleshooting, and treatment. it is organized in the manner of case scenarios...I urge you to check it out.

warmly

theonlychances.