Does a PVC cause a PM to begin pacing?

My PVC events only occur during strenuous exercise. I have a pacemaker because of 2nd degree A/V block. Sometimes during running, my PVCs trigger an SVT/AVNRT event. I've had an ablation procedure done that has eliminated nearly all of my SVT events. But, I still have a few PVCs during running. Immediately following a PVC, my breathing rhythm feels very labored and inefficient and usually continues that way until I stop. Usually after stopping, for as short of a period as 15-30 seconds, I can feel my breathing rhythm return to normal and I can resume running without a problem.

My questions: Does a PVC event make a pacemaker start pacing? And, is my PM pacing, the reason for the labored and inefficient breathing rhythm I feel immediately following a PVC? Is it normal for a PM pacing to make my breathing feel different as compared to normal, unpaced breathing?

Thanks for any input.

4 Comments

PVARP

by golden_snitch - 2014-07-30 01:07:07

That automatic capability needs to be activated, I guess, at least that is the case in my pacer. It has an automatic PVARP management, and a setting for "PVARP after PVC" that is programmed to be 325ms, when it's just 175ms for the normal PVARP. Not sure what Boston Scientific has.

You don't actually feel this longer PVARP, you feel the compensatory pause after a PVC - and that is physiological, not something only the pacer does!

So, I'd not worry about this at all. Actually, with a second degree heart block when exercising only, that the pacer needs to manage, there isn't much to worry about. Your sinus node will dictate the pace, and all the pacer needs to do is to make sure that, when a 2:1 block occurs, it provides a stimulus in the ventricles.

Inga

Compensatory pause

by golden_snitch - 2014-07-30 03:07:52

Hi!

After a PVC you usually get a compensatory pause, and that's what you might be feeling. I feel them, too, at rest and when I exercise. My heart rate monitor shows that just for a couple of beats the rate drops a little (2 - 5 bpm less), and then it's back where it was before the PVC.

Some pacemakers automatically prolong the PVARP (post ventricular atrial refractory time) after a sensed PVC to avoid tracking of a retrograde p-wave, which could initiate a pacemaker mediated tachycardia.

I don't think that the PVCs would make your pacemaker start pacing. With a second degree heart block, it should only pace when your AV-delay exceeds a certain time interval (in DDD modes) or when a certain number of heart blocks occurs in a defined period of time (in Medtronic's MVP mode, mode switch from AAI DDD).

Inga

post ventricular atrial refractory time?

by chip j - 2014-07-30 09:07:35

Inga, thanks again. Above, when you posted, "Some pacemakers automatically prolong the PVARP (post ventricular atrial refractory time) after a sensed PVC to avoid tracking of a retrograde p-wave, which could initiate a pacemaker mediated tachycardia.", would a pacemaker that has that automatic capability always prolong the PVARP, regardless of how my EP may have programmed it? I have a Boston Scientific Advantio PM. I will ask my EP the same question at my next appointment.

Advantio's PVARP setting

by chip j - 2014-07-30 09:07:46

I didn't even know where to start until you posted about PVARP, after PVC. After your post, I researched and found the following specs, for my pacemaker:

"PVARP After PVCa (ms) Options:Off, 150, 200, ..., 500
Nominal default setting: 400 (Tolerance ± 5 ms)"

So, your statement, "guessing" that the automatic capability needs to be activated, is correct, since the specs above have an "off" setting. Thank you, now I know exactly what to ask my EP. I have a feeling my PM's PVARP after PVC is probably switched off. I think my A/V delay is set at 300ms to prevent HR drops when I have an AV blockage. Perhaps the PVARP can be set higher (400-500 ms) and prevent the unusual rhythm I'm experiencing, following a PVC event.

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