What is PVARP

I just joined Pacemaker Club and this is my first post. I’m hoping someone will be able to give me a layman’s overview of PVARP. I’m trying to get a basic understanding of it in an attempt to get my pacemaker settings properly adjusted. The “pacer” says her hands are tied by PVARP and cannot make the changes I’m asking for.

A bit of history: I’m a 62 yr old male and I’ve been very active most of my life until a number of years ago when I suddenly could no longer exert myself without feeling wiped out and exhausted. I’ve run more than 100 miles in a week, a 2:49 marathon, days when I ran 3 times, biked twice and threw in a bit of basketball in between, then all of a sudden mowing lawn was an effort. In September of 2018 I was given a pacemaker (Boston Scientific L311 Accolade MRI) because of an AV block cutting my pulse to about 50%. My resting heart rate could drop below 30 but I never had symptoms other when trying to exert myself. When I was very active my resting heart rate was low 40’s.

Now my dilemma: As far as I know the Sinoatrial (SA) node is functioning properly so I thought the pacemaker would follow the SA node and fill in the missing beats, increasing my heart rate as driven by the SA node. But I still cannot exercise much. I’ll go for a 4 mile fast paced walk in the hills and my Garmin watch HR monitor is indicating upto 140 bpm. When I try to run I only get about a half mile before having to walk again. The HR monitor is locked in at 140bpm, just what the upper limit of my PM is set at. I’ve tried to get the “pacer” to increase the upper limit but she says that the PVARP will not allow it.

She has the PM setup with “blended response” which uses the accelerometer and respiratory sensors. Since my SA node is working fine I do not see a need to have any type of rate response and feel that is just complicating things. I have not been able to find out the max heart rate designed into the Accolade.  I’ve been trying for months to be given an exercise test to see what the PM and SA node are doing but got nowhere until I said I would have to find someplace more accustomed to active people with pacemakers. I still do not have a commitment for the stress test but I’m hopeful.

Any ideas? Is the PVARP issue always a problem or is it related to having the rate response turned on? A max of 140 bpm seems like a low number to me. Of course the “pacer” is stuck on the 220-age guideline and has repeatedly told me she doesn’t have the time to teach me about PVARP.

Thanks all!!


5 Comments

No time to teach?

by AgentX86 - 2019-03-04 11:04:04

Fire her and find another tech.

I agree, if what you say about your SI node is correct. Perhaps you shouldn't have rate response enabled. Talk to your EP about this. He should be able to explain why you're paced as you are.

As far as PVARP goes,  <https://www.medtronicacademy.com/features/automatic-pvarp-feature>

It is not as simple as that ...

by IAN MC - 2019-03-04 13:33:30

It is possible to have a normally functioning sinus node and yet still need Rate Response for a variety of reasons.

For example , some drugs ( beta blockers, calcium channel blockers, amiodarone  ) can cause chronotropic incompetence which leads to the need for Rate Response.   Maybe they cause sinus node problems, maybe not ??

Ian

Settings

by steppingstones - 2019-03-04 23:16:56

I have had a Boston Scientific since 2007 actually on my 3rd device of their best.  When I can't get a logical answer from my EP's office, I call the manufacturer.  They have ALWAYS been great.  No one knows the product like they do and its limitations and behaviors.  Being that person "doesn't have the time"....maybe the rep from the company needs to come in.  I have had that happen to.  Best of luck to you....it is frustrating.

PVARP

by Gotrhythm - 2019-03-07 17:24:04

In a normal heart, the upper chanbers of the heart contract just a little before the lower ones do. Put very simply, the PVARP is about the lenght of time between contraction in the atria, and contraction in the ventricles. It's a safety function. Its purpose is to prevent pacemaker mediated tachycardia--or runaway pacemaker syndrome. The PVARP can be shortened or lengthened within certain parameters, but it can't be done away with.

PVARP - My Update

by rjtchris - 2019-03-12 10:53:47

I’ve been unable to find a description of PVARP that is not in very technical and medical terms. Some discuss it as a feature of the pacemaker and others discuss it as a characteristic of the heart. By breaking down the individual components of the term “Post Ventricular Atrial Refractory Period” I’ve been able to come up with my own simple description. When the SA node sends it’s electrical signal to the atria, the atria contracts and pumps blood into the ventricle. After a slight delay to allow the blood to flow into the ventricle the AV node passes the electrical signal from the atria to the ventricle causing the ventricle to pump the blood through the body. After the electrical signal from the SA node gets to the atria and the atria contracts (depolarization) there is a period in which the atria will not respond to the next electrical signal. This is called the refractory period. The same is true of the ventricle. Once the heart muscle is depolarized it needs some amount of time to reset. It can respond before being fully reset but the contraction would be weaker. So the PVARP of the heart is the time needed between electrical signals for the heart muscles to be ready to do their job again. The PVARP concerning the pacemaker is the programmed delays to allow time for the heart to be ready for the next contractions.

I have a stress test scheduled and I’m hoping that during the stress test enough information will be obtained to help make the adjustments needed to allow me to exert myself. I’m particularly interested to find out what the SA node is doing. Is it increasing as I increase my physical effort? I’m hoping if the SA node is working correctly (and so far I have not been told otherwise) that adjustments can be made to allow the pacemaker to keep up. At present my upper limit is set to 140bpm which I do not feel is high at all; after all most healthy hearts can beat much faster. I’ve seen the refractory period often listed as roughly 250ms. How much does this vary from person to person? At a heart rate of 180bpm the time between beats is 333ms. So even at 180bpm there is plenty of time for the muscle to reset unless the individual’s refractory period is much longer than typical. My fear is I’ll discover that the PM I received cannot be adjusted or reprogrammed enough to allow my pulse to get to a sufficient level and that the PM was not a good choice for a physically active person.

If the atrial is working faster than the pacemaker is pacing the ventricle, then doesn’t the atrial try to pump blood into the ventricle which is already holding blood? Is that harmful?

I’ll update after the stress test. Hopefully whatever information I can share will help someone else. I’d hate to mislead anyone so if anything I’ve written above is wrong please correct.

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