Pacer setting is set very high....

no worries

by Tracey_E - 2024-05-20 15:37:59

Most of us with av block pace 100%, so 97% sounds about right. Don't stress over the number. If you feel good, you are pacing the right amount. 

If I had to take a guess, that 30 you used to have was more about the av block than your natural rate being that low. You want the pacer pacing the ventricles every time the atria beats. I don't get why sometimes they try to set it so low that it doesn't pace. That's the whole reason we have it- to pace when we need it. And with av block, the atria generally works normally but the signal isnt getting through to the ventricles so we need it nearly every beat. The pacer's job is to keep the ventricles in sync with the atria, whatever rate the atria is doing.

It doesn't hurt anything to have the upper limit at190. If by chance you ever get  your atrial rate up that high, the pacer would make sure the ventricles keep up. It's good to have a cushion, have it set above where we normally get when we work out. My upper limit is 190 also, I normally stay 150-160 during workouts, sometimes closer to 170. Mine was also set after watching me on a treadmill. My previous device only went to 160 so every time I got over 150 I felt bad and had to stop and bring my rate down. Super frustrating, and I feel so much better with my current one. It's important to have a cushion at the upper end if we like to work out hard!

It is possible, but not particularly common, that pacing can cause the heart function to drop over time. Not atrophy, that means loss of muscle, but reduced ejection fraction. Ejection fraction is how hard the heart beats, the percentage of blood squeezed on a contraction. This is why we get regular echos, to stay on top of it and watch for any changes. If EF drops, there are medications that can help, or they can add a 3rd lead to the pacer to pace both ventricles. So, there are treatments if it happens.

However, the risks from the heart being out of sync are far higher than the risks of pacing. If the atria is beating at 60 but the ventricles are only pushing it out at 30 (every other beat) that means the heart is filling but not able to push the blood out. Think overinflated balloon. This is far harder on the heart, and why avoiding pacing doesn't make sense to me. Unnecessary pacing is bad. Pacing to keep the ventricles in sync with the atria is necessary and good. 

I've been paced 30 years, and my EF hasn't dropped at all. My ep said that if it doesn't drop within 5 years, he almost never sees it drop later so he does not consider this a risk for me. He actively encourages me continuing to push myself working out, having a strong heart is the best thing we can do for ourselves. 

more

by Tracey_E - 2024-05-20 15:43:50

Battery life has more to do with condition of the leads, placement of the leads, extra bells and whistles we use, safety margins, how the heart responds to pacing, than how much we pace. Percentage pacing is a small part of battery usage. 

The device isn't doing the work. Your heart still is. All the pacer does is send a tiny signal that mimics what the heart should have done on its own. The heart responds to this signal by beating. It doesn't take over the beating, merely initiates it. 

I'm a big fan of having a doctor who's an athlete. They DO get us, they understand the importance of staying fit which means they will prioritize helping us stay active and go that extra mile to fine tune our settings and work with us until we are feeling our best. It's also good to have one who has other young(ish lol) and athletic patients.  

Concise explanation

by IrishToast - 2024-05-20 18:27:03

That was very helpful, Tracey_E. I am 5 months new to all this and still trying to understand it all. I finally have an idea of what ejection fraction means. I already understood that my PM only prods my heart, not take it's place. I was still confused about EF, but you made it understandable.

Settings

by AgentX86 - 2024-05-20 18:54:56

You say that your heart rate was down into the 30s and they set the minimum to 40bpm. This indicates that something other than a second-degree heart block and LBBB is going on.  The fact that you're in the 30s, even as a athlete, and they want to correct it, points to SSS (Sick Sinus Syndrome), in addition.

Since you were in the 30s, and now your PM is set to 40, tells me that you're being paced in the atrium (for SSS).  The period of time that you would have been in the 30s, you're now being paced. This will add to the percentages.  Look at your report.  There should be an atrial percentage and a ventricular percentage, listed. The AP points to the pacing for SSS, and the VP points to your LBB block. Note that the AP is highly sensitive to the minimum pacing rate. Raising that rate by a very small amount can have a huge effect on AP.  It's theoretically possible to go from 0% to 100% with only a 5bpm change.

You say that your maximum tracking rate (the maximum rate the ventricles will track the atria) is 190, but you rarely get above 140.  This means that the max tracking rate is irrelevant. You never get there.

You may have trouble with other settings, though. The ADL (Average Daily Living) rate is set to match your daily use, sort of the walking around shopping rate.  There is a slope from your minimum to ADL and another from from the ADL back down to the minumum (resting) rate.  There are also dwell times involved (how long it takes to respond to any stimulus) and sensitivity (how much activity/motion it takes to register at all).

The same sort of settings are used between your ADL and MTR.  All of these have to play together to get you maximum performance. When you're running, for example, you may be hung up in one of the plateaus (resting or ADL) until some time after you really need the HR increase, or the increase isn't fast enough.  This has to be tweaked for you and your lifestyle. 

Unfortunately, these settings are a tradeoff, and it's not always possible to set them all for every scenario that you're accustom to. You have to work with your device tech to get these as close as you can to affect your life as little as possible.  Sometimes it takes a long time.  Sometimes it can't be done. I'm there now, except that I only have one exercise, but effectively no atria, so everything gets more difficult,

Why?  It's well known that endurance athletes have a much higher incidence of electrical problems in the heart.  Usually it's Afib, but it can be anything.  The working theory is that with over-conditioning, the heart gets larger, it causes fibrosis of the heart muscle.  The fibers don't conduct electricity, so circuits are interrupted. 

....or, in your case it could be that you were born at the wrong end of the gene pool, or simply have bad luck.  For each individual the answer is unknowable. In general, endurance athletics isn't all that great for the heart.

As far as the percentages go, I find it interesting as an acedemic exercise but mostly irrelevant.  Even if wasn't dependent, it would only be of interest.  It doesn't mean much.  Really, battery life doesn't matter much.  When it's dim, replace it. IIRC (I don't have the manuals for my PM here), the penalty for 100% biventricular pacing, over 20%(?) was ten years to eight.  I've had mine a bit over 6 years and the reports say 2.3 years left.  We'll see.

The bottom line is that it works, and you still here. Everything else is icing.

pacer setting

by MartyR - 2024-05-21 12:18:34

THANK YOU VERY MUCH for the detailed explanations Tracey and AgeX86!!  You always provide great insight! 

A few follow-ups:  My ejection fraction is around 70% which is great and I even asked my Electro if he was concerned it was too high (other issue if it is too high, but he is not concerned).  I do not have an enlarged left ventricle; ruled out obviously with several echos and an mri in 2022.  My resting rate has been in the 30's for years with no issue.  I do not believe that I have SSS because electro has said 2 atriums are good and do not need pacing.  I definitely have AV node block 2:1.  I will ask about this at tomorrow's appt..  and will also inquire about increasing to 45 bpm because I have been getting tired in early afternoon.    

Tracey, on the statement that unnecessary pacing is bad, can you further explain?  I think that is the crux of my question of my pacer "working" when my rate is between 40 bpm and 140 bpm.  Essentially, today, if I could run and keep my rate under 140, I would not need pacing.  I will add that my initial Electro said that if I did not have the implant, I likely would have seen a total block within 5 years while simply walking across the room.

Agent X86, my wife and I have had heated discussions about the cause, so I cannot let her read your post :).  I have to admit that common sense would point to endurance sports...

Again, thank you SO MUCH for your input!

unnecessary pacing

by Tracey_E - 2024-05-22 11:13:48

Unnecessary mostly applies to people with sinus dysfunction, not av block. With av block, they can adjust the delay to give the ventricles more or less time to beat on their own. Too short of a delay would mean extra pacing because it's not giving the ventricles enough time to do it naturally. If you don't have av block but have a very short delay which causes ventricular pacing, this is unnecessary ventricular pacing.

That's not how the pacer works with av block, though. It's not setting the pace, it's playing follow the leader. The atria beats normally, the pacer is needed to complete the broken circuit and make sure the ventricles beat whenever the atria does. 

Agent gave an excellent explanation of upper and lower limits. If your resting rate (with pacing) is still in the 40's and you are getting tired, you may feel better with a bit of atrial pacing to bring it up. The amount of pacing is less important than how you feel. Please don't be afraid of increasing pacing if you feel better with it. 

Yes, block almost always progresses. That's why most of us with av block pace ventricle 100%, because the signal never gets through from the sinus node to the av node. Some people go into block only on exertion, but most of us reach a point where we are always in block, unrelated to what we are doing. When this happens, the atria is beating normally but the ventricles beat at random because they never receive a signal from the sinus node. 

If going over 140 running means pacing but having a better run, then go over 140 and let the pacer do its job. Fear of pacing should not be a reason to hold back. 

High EF is terrific! 

No enlarged left ventricle means you were paced before any damage was done. This is great news also. 

If we have to have a heart condition, you've got the "best" one. Your heart is otherwise healthy, the problem is fixed with pacing, and it was fixed before there was damage. Try not to stress over the details, esp how much you are pacing. If you feel good, the amount of pacing is right. The odds of the pacing causing new problems is very low. My ep said reduced EF due to pacing happens well under 10% of the time, and he feels many of the ones who do see a reduction would have seen it with or without pacing. You are truly in the best possible position. Keep exercising and taking care of yourself, stay on top of your check ups, and try not to worry. Most of us find that it takes time to adjust to the idea of having a pacer, and to learn to trust it to do its job. A day will come soon when you don't give it a thought. 

Settings

by MartyR - 2024-05-23 09:43:56

Tracey, THANK YOU again for your great insight!!  Very much appreciated!

To Tracey_E or others who may know?

by Clayok - 2024-06-11 02:38:56

I see suggestions for having a doctor/ I assume EP that is an athlete or works with them. I'm in Southern California, and suggestions or recommendations on help tracking in down with this knowledge. 
 

I want help to adjust and fine tune my pacemaker as I get started using it. Just had implanted 2-3 months ago for bradycardia/ seemingly sic sinus?

thank you 

clay