# Pacemaker Malfunction?



## VFlutter (Nov 4, 2012)

I had an interesting case at work today, I'll give my interpretation of what happened but I am not sure if I am correct or not. Feel free to add input.


Pt went into SVT 150-200s for ~15 seconds at which point his AICD attempted to overdrive (ATP) pace which was unsuccessful and lead into V Tach in the 200s which lasted ~15 seconds before his AICD fired which successfully terminated the rhythm. 

I am suspicious of the overdrive pacing. It seems to be poorly sensed and possibly created an R-on-T like phenomenon. However, the beat immediately after the pacing appears to be a sinus beat which then leads into the V Tach. 







Hopefully this works since this is the only way I could capture the strips


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## sir.shocksalot (Nov 4, 2012)

It's hard to tell with the fusion beats, honestly it looks like the pacer spikes are smack in the middle of the QRS complex causing a nice, wide fusion beat.

I don't personally think this was R on T simply on the basis that I can't see if a pacer spike hit a T wave in the right spot or not. Also the following sinus beat makes me think that there was not an R on T event, Every R on T that I have seen the V-tach or V-fib is immediately following the R on T. This might just have been spontaneous V-Tach. This guy has a pacemaker and defib for a reason, clearly his history indicates that he is at risk for arrhythmias.

At least going in to V-Tach fixed his SVT... very cool strip and case though. What was his hx and admitting diagnosis?


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## VFlutter (Nov 4, 2012)

sir.shocksalot said:


> It's hard to tell with the fusion beats, honestly it looks like the pacer spikes are smack in the middle of the QRS complex causing a nice, wide fusion beat.
> 
> I don't personally think this was R on T simply on the basis that I can't see if a pacer spike hit a T wave in the right spot or not. Also the following sinus beat makes me think that there was not an R on T event, Every R on T that I have seen the V-tach or V-fib is immediately following the R on T. This might just have been spontaneous V-Tach. This guy has a pacemaker and defib for a reason, clearly his history indicates that he is at risk for arrhythmias.
> 
> At least going in to V-Tach fixed his SVT... very cool strip and case though. What was his hx and admitting diagnosis?



Admitimg diagnosis was CHF exacerbation. Received ICD due to EF < 30%

Also, if you look in the beginning of the first strip there was pacemaker pseudofusion prior to the event.


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## Christopher (Nov 5, 2012)

ChaseZ33 said:


> I had an interesting case at work today, I'll give my interpretation of what happened but I am not sure if I am correct or not. Feel free to add input.
> 
> 
> Pt went into SVT 150-200s for ~15 seconds at which point his AICD attempted to overdrive (ATP) pace which was unsuccessful and lead into V Tach in the 200s which lasted ~15 seconds before his AICD fired which successfully terminated the rhythm.
> ...



Very cool strips!

For those not familiar, antitachycardia pacing--whether burst or ramp--attempts to capture ventricular reentry circuits and thus cause them to terminate once the impulse generation stops. Usually ATP is meant for ventricular dysrhythmias and not atrial tachycarrhythmias, however, some newer devices are programmed to do both. There is always a risk of VF with ATP, but in this case I don't believe the overdrive pacing caused the run of VT after the run of SVT.

It would be interesting to see what the EGM showed on the atrial and ventricular channels during this period.


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## mycrofft (Nov 6, 2012)

How old were the implanted electrodes? Eventually they can become encysted or calcified which can affect reception and discharge. Might that then cause distorted perception by the pacer of pt status, and/or odd discharge waveforms?


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## Handsome Robb (Nov 6, 2012)

Nice strip! I bet that set off some fun alarms.

I'm going to agree with shocksalot here, seems to PSVT then VT I don't think the ATP attempt caused it with the sinus beat after it failed to convert.

Was this patient in bigeminy prior this?


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