confused on ventricle overpacing i.e 99%

Hello everyone. Trying to help my 80 yo mother with her 2 month old pacemaker. Symptoms have been improving but she still has moments of lightheadedness upon standing and heavy fatigue. She was diagnosed with 2nd degree AV block (wenkeback) and bradycardia. 

Im wondering if her settings need to be adjusted. Im also concerned about over pacing (VP>99%).  Is this still a concern for (premature heart failure or left ventricle issues). Ive been reading some pubmed studies but not sure if things have changed.

her settings are as follows

Mode: DDD
Base Rate 50 bpm
Max Track Rate:  110 bpm
Paced AV Delay 250 ms
sensed AV Delay 200 ms

AP 39%
VP >99%



ventricular pacing

by Julros - 2022-09-05 23:22:47

The pacer is set to pace within pre-set parameters. If your mother is pacing >99%, then her ventricles are not receiving an electrical signal from the atria, so the pacer is firing. Perhaps her block has increased to a complete heart block. I'm not sure I understand what you mean by over-pacing. Yes, in some individuals, right ventricular pacing can induce heart failure but that happens over months and years.I doubt that is responsible for your mother's symptoms. The pacer cannot respond instantaneously to position changes, so it is best if you mom can change positions slowly. Her provider may be able to adjust the responsiveness settings, but her symptoms may not be related to the pacer at all. This is definitely worth a discussion with her provider. 

99% VP

by AgentX86 - 2022-09-05 23:57:08

As julros indicated, a pacing percentage of 99% just means that the pacemaker is doing its job. It could be that your mother's heart block is complete but highly unlikely after only two months. It's more likely that her EP has set the sensed delay too low so the pacemaker beats the AV node to the punch. My bet is that this is intentional, for some reason (I'm not a doctor). It's certainly not something to worry about. A good number of people here are paced 100%.

As far as being dizzy on rising, this is very common too. The solution they'll give you is ("don't do that"). Rise more slowly and carefully. This probably "orthostatic hypotension". When one changes positions quickly, the blood pressure drops momentarily, causing a drop in the blood to the brain, resulting in dizziness. It's extremely common and not generally a problem.

Be very careful with Dr. Google. He'll drive you insane. One thing the Internet has done it to make life faster, including the path to hypochondria.

She'll also have all sorts of bumps in the night that were ignored before but with any life-changing experience, we turn our focus inward and become conscious of every little thing. She can't blame everything on the pacemaker. Chances are that the bumps were there all along. That doesn't mean that she should ignore her body but, rather temper it, hopefullywith knowledge. Pretty soon she'll become desensitized to these little bumps again and all but forget that she has a pacemaker.

heart failure from pacing

by Tracey_E - 2022-09-06 11:38:22

Many of us with av block pace every beat, and have for many years. Don't let the number scare you. For us, that's normal and it just means the pacer is doing its job.

It is possible for ventricular pacing to eventually cause heart failure, however it's not common. My ep said that if ejection fraction stays the same for 5 years being paced, he rarely sees it happen later. My EF has remained the same for 28 years of pacing every beat. Also, the way they place leads has changed so it's easier on the heart now than it used to be.

The odds of developing problems from being paced are significantly smaller than the odds of serious issues from untreated heart block.It's no different than medication side effects, if you start reading too much you'll be afraid to take it and forget why you needed it in the first place. As with any treatment, our doctors will weigh the cost/benefit. With pacing, the risks are very low and the benefits are high.

Most of us have an echo every year or every other year so they can keep an eye on our heart function. If it starts to drop, there are treatments. 

How is her bp? That can cause dizziness on standing.

Is she on any new meds? Many heart meds cause fatigue the first few weeks.

When in doubt, check with her doctor. 


by vivianne - 2022-09-06 13:13:04

Thanks for the responses and perspectives. When I pointed out the issue of overpacing with her cardiologist, she agreed that the risk of adverse events are increased but didnt want to adjust the settings now and could revisit later on.

I should add is that her doctor isnt an electrophysiologist. She does have a Nurse Practioner EP that does the checks but Im thinking she may be better off with an EP doc. 


by Tracey_E - 2022-09-06 14:41:29

If a NP in working in an EP's office, she is probably in excellent hands. They usually work very closely with the EP. In my EP's office, the NP is dedicated and only does pacers, so she knows it as well as - or maybe better than- the EP. I usually see both of them when I go.


by vivianne - 2022-09-06 17:20:40

@tracy_e That is probably often true but in my mother's particular situation the supervising cardiologist is'nt an EP.  



by vivianne - 2022-09-06 17:26:18

So just got back from seeing the NP and she adjusted my mom's pacemaker from 50 to 70 bpm and turned on rate response.Her resting heart rate used to be in the 40s pre PM .


by Tracey_E - 2022-09-06 17:54:37

It's very common to have to fine tune the settings, sometimes more than once. They send us home with a good guess but we are each different so sometimes it takes a bit of trial and error to get it just right. 


by vivianne - 2022-09-06 20:56:37

yes Im hoping for the best. 50 to 70 seems like a big jump but Im hoping the extra circulation will have all sorts of benefits.


by dwelch - 2022-09-06 23:51:01

I have a biventrical, and complete (level 3) av block, so both ventricals are paced at 99/100%.  This is perfectly normal and expected for complete block.  Level 2, maybe not, but if she is pacing at 99% then it is probably a bad case of level 2 or really level 3.  But 99./100% for av blolck is no concern whatsoever.  If you have complete as in my case, and it is not near 100% then that would be a concern.

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