ECG Quesction

[NPO]

Anyone know the cause and or name of the small spike seen here?

Patient has extensive cardiac history, but no pacemaker.

We first thought it was some sort of artifact but as we moved the patient it occurred every 5-15 seconds. Not always in the same spot in the rhythm.

Just curious as we were discussing it. I know there's not a lot to go on.

 

[TransportJockey]

And no pacemaker? I swear that looks like a pacer spike. I have no idea, but I'm curious.

 

[FLdoc2011]

Probably just artifact. The machine may also be interpreting (wrongly) that part of the ECG as from a pacer and placing a "pacer spike" there.

The current bipolar leads used on pacers deliver very little energy and the actual pacer "spike" can be extremely low amplitude or not seen at all on an ECG.

Some telemetry devices (and I would assumed ECG machines/defibs) have a setting/mode that can be turned on and they look for the electrical characteristics of a pacer firing and place a spike of higher amplitude on the monitor just to make it easier to see. Sometimes though it picks up interference thinking that's a pacer and places a spike.

We've had that happen numerous times in the ICU where nurses call thinking there's a rhythm change or something.

 

[Akulahawk]

That looks very much like a pacer spike. You sure there's no pacer? It very could be a pacer that has lost capture for whatever reason. Did the patient bring his/her own cellphone along for the ride? It could be cellphone RFI, especially if the phone is a little older or is using an RF band that your monitor is sensitive to.

 

[NPO]

Pt was stripped down in a gown being transported for MRI. Pretty sure no pacer, haha.

 

[SeeNoMore]

Yeah it's either intermittent atrial pacing (which you say it is not) or artifact.

 

[VFlutter]

Any other type of electrical never stimulator? I am assuming no because of the MRI. But many people forget about bladder, peripheral, or spinal never stimulators that can cause similar artifact.

 

[SeeNoMore]

Good point.

 

[NPO]

Any other type of electrical never stimulator? I am assuming no because of the MRI. But many people forget about bladder, peripheral, or spinal never stimulators that can cause similar artifact.

Funny you should mention that. I don't know what those are, but the door to the MRI said NO NEUROSTIMULATORS.

I figured its probably some random artifact. It just happened a lot.

Edit: just found out, it was showing up on the MRI heart monitor as well.

Just like the number of licks to the center of a tootsie pop, the world may never know.

 

[Akulahawk]

Funny you should mention that. I don't know what those are, but the door to the MRI said NO NEUROSTIMULATORS.

I figured its probably some random artifact. It just happened a lot.

Edit: just found out, it was showing up on the MRI heart monitor as well.

Just like the number of licks to the center of a tootsie pop, the world may never know.

Then that's not artifact. There's some kind of stimulator zapping along somewhere in that patient's body.

 

[DesertMedic66]

Patient swallow any batteries lately...

 

[Christopher]

Anyone know the cause and or name of the small spike seen here?

Patient has extensive cardiac history, but no pacemaker.

We first thought it was some sort of artifact but as we moved the patient it occurred every 5-15 seconds. Not always in the same spot in the rhythm.

Just curious as we were discussing it. I know there's not a lot to go on.

Probably just artifact, maybe electrical, which the monitor's pacemaker filter helped show you.

It certainly does look like a paced P-wave, although the P-P' is 920ms which is an atrial rate of 65 bpm...which is an odd lower rate limit.

 

[OnceAnEMT]

Then that's not artifact. There's some kind of stimulator zapping along somewhere in that patient's body.

Quick question on this. Are pacemakers always supposed to show a spike right before the P wave (acting as SA)? Or do they spike at various points (or does that just mean they're malfunctioning )

Would something like a neurostimulator, or any distal stimulator, be able to show a spike on a 12 lead..?

 

[Christopher]

Quick question on this. Are pacemakers always supposed to show a spike right before the P wave (acting as SA)? Or do they spike at various points (or does that just mean they're malfunctioning )

Would something like a neurostimulator, or any distal stimulator, be able to show a spike on a 12 lead..?

1. Are pacemakers always supposed to show a spike right before the P-wave (acting as SA)?

If the pacemaker has an atrial pacing lead, then yes it can show the spike just prior to the P-wave. In this instance it would be acting in lieu of the SA node (or supplementing the SA node).

The "mode" of a pacemaker can be determined by its 3 letter code (NASPE code/NBG code, may have more letters), such as VOO, VVI, DDD, AAI, etc.

The first letter is the chamber(s) being paced: A = atria, V = ventricle, D = both atria and ventricle can be paced.

The second letter is the chamber(s) being sensed: A = atria, V = ventricle, D = both atria and ventricles can be sensed, O = no sensing.

The third letter is the response to sensed impulses: O = no response, I = inhibit pacing, T = triggered pacing, D = inhibition and triggering.

A paramedic who paces a patient using their monitor in fixed mode is doing VOO pacing. V = pacing the ventricles, O = no sensing, O = no response.

A paramedic who paces a patient using their monitor in demand mode is doing VVI pacing. V = pacing the ventricles, V = sensing the ventricles, I = do not pace if it senses the patient's own ventricular impulses.

A patient with an atrial pacemaker could have an AAI setup to, (A) pace the atria, (A) sense for normal atrial beats, (I) and do not pace if the patient's own P-waves are working.

An extremely common pacemaker setting is "DDD", which means (D) pace the atria and/or the ventricles, (D) watching both for normal activity, (D) don't pace a chamber if it is working but pace a chamber that "falls behind".

2. ...or do they spike at various points?

This depends on what pacing leads are present. An atrial lead should pace just prior to the P-wave. A ventricular lead should pace just prior to the QRS complex. Patients with biventricular pacing will have 2 pacing spikes for their QRS in close succession. Usually one just before the QRS and one ~20ms later during the QRS.

3. ...or does that just mean they're malfunctioning?

Sometimes you can determine if the leads are misplaced or if the sensing threshold is too low, or other problems with pacemakers based on what you see it doing. If you do not know the mode of operation, you can make educated guesses based on its behavior.

In this case, we have a lone "paced" P-wave (I'm using quotes because I don't believe it is) which is 920 ms after the prior P-wave. If this were atrial pacing, it would mean the "lower rate limit" is set to 65 bpm.

Sometimes you'll see spurious pacing spikes in patients with pacemakers which may not indicate a problem. If the timing is just right the patient's own heart may fire at nearly the same time the pacemaker fires, however, typically the pacemaker will notice this and stop pacing.

Pacemakers are wonderfully complex devices, with custom programming to handle a wide range of scenarios. Many include rate modulation to ensure the atrial or ventricular rate meets the cardiovascular demands of the patient!

4. Would something like a neurostimulator, or any distal stimulator, be able to show a spike on a 12 lead..?

Yep, this sort of artifact is commonly seen on 12-Lead ECG's due to the filter settings. In monitoring mode it may not be visible.

 

[OnceAnEMT]

Thank you very much for this break down! I had no idea pacemakers had that kind of variety. I'll look into that today. As well, I'll take a look at the 12 leads we run at work and see what settings they are on. Thanks again.

 

[NPO]

Follow up. We found the culprit, and it was no where anyone was looking.

On our Zoll M-Series CCT, the 4 lead has breakout box with a port for the 12 lead cord. When not in use, the 12 lead port is protected with a plastic plug. This plug has small electrical contacts. I first noticed it when popping the plug off last week. I saw a sharp spike on the monitor as the contacts separated. The plug had apparently been rattling.

 

[SandpitMedic]

Extraterrestrial.

Not the plug connectors bro.

Your patient is a Martian.

 

[rmena]

Had a call once of a dude that had 'no medical history'...youre sure? yes absolutely no history of any medical conditions...never been to the doctor? Ok....well, ok...we hook him up to an ecg and about 2 milliseconds after he says, "oh here is a card that my cardiologist gave me." It was a post op instruction card for pacemakers and had some of his settings on it. where was it? not in a wallet...in his diabetic case.