Pacemaker Pacing 100% What does this mean? What is Pacing Dependent?

Cardiac Pacemaker – Pacing Percentages – Pacemaker Dependent

What does the term “100% paced” actually mean? Does that mean that my pacemaker is working 100% of the time or does it mean something else?

I received this question last night and it does bring up a subject I had been meaning to explain – Pacing Percentages.
What is 100% Cardiac Pacemaker Paced?
In dual chamber devices you actually have two pacing percentages, one for the top of the heart (Atria) and one for the bottom of the heart (Ventricles). These tell us what percentage of the time that part of the heart needed to be told to beat by the pacemaker. So the short answer is Yes, 100% Paced means that the pacemaker always has to make that part of the heart beat. If the patient was 50% paced, this describes a person for whom the pacemaker is having to initiate 50% of the beats.

From starting this website and dealing with my patients I know that patients focus on this number as a benchmark for their cardiac/pacemaker health. PLEASE DON’T 🙂 
This number is how dependent you are on the pacemaker to relieve your symptoms and not necessarily how dependent you are on the pacemaker to keep you alive. I will give an example which will hopefully help explain this concept…

A patient goes to the doctor complaining of being dizzy and lightheaded. Tests show that this patient has a heart rate of 40-50 BPM (Beats per minute) and requires a simple top chamber pacemaker (AAI Device) to increase his heart rate. The pacemaker is implanted and the base rate (the slowest the pacemaker will let the heart get) is set to 60BPM. On his first follow up, it is found that he is 100% paced. This is because his heart never gets the chance to initiate a beat because it does it too slowly and the pacemaker gets bored of waiting! (Ever asked somebody to do something and they have taken so long you have decided to go ahead and do it yourself?)
So even though he is 100% paced if his pacemaker stopped working the chances are his heart would return to 40-50BPM and he will just have a return of symptoms.

Am I Pacing Dependent?

So if you are 100% paced it does NOT necessarily mean you are dependent on the pacemaker to stay alive – just that it works a lot of the time to relieve you symptoms.
Why do technicians focus on this number then?
Well studies have shown that the more you pace the heart, over time this could cause a decrease in the hearts pumping functionality (Ejection Fraction). In essence, the more you pace the heart the less efficient the heart will work over time. So us technicians do try and decrease the percentage of time that the pacemaker is initiating a beat to minimize any side effects the pacemaker could have.
Like any medication there is a side effect and that’s why the minimum dose that works to relieve your symptoms is the right dose. That is what we are doing with this number, we are trying to minimise your dose to reduce potential side effects 🙂
This is becoming less of an issue as moving forward Cardiologists have started using septal lead placement (putting the lead in a different area of the heart) to try and minimise this side effect – especially in the younger population.

A complete explanation of these topics and more is available in the book Pacemakers Made Easy by Carl Robinson.

I hope this has relaxed some of you and dispelled a few myths about pacing 🙂
Time for a Cup of Tea (how very British)
Thanks for Reading
Cardiac Technician
Image courtesy of Master Isolated Images /

Comments 26

  1. Pacing of 2013 does not cause reduced cardiac function as long as the electrode of the pacemaker is placed at the His bundle. Patients who have been paced into heart failure have had there ventricles paced there and the heart has always healed itself as far as I know. Google Pacemaker Patient Advocacy. We learned at the annual meeting, HRS, this summer that His bundle pacing takes no longer to implant than conventional pacing that bypasses the cardiac conduction system that can cause heart failure, using catheter introduced leads.

  2. You are of course correct and this is what I eluded to with my comment on Septal Lead Placement (His Bundles). However this evidence is relatively new and so I wanted to focus on the majority of current pacemaker patients that are out there at the moment whom have RV Apex leads. Thank you for your feedback though I will be sure to check out the Pacemaker Patient Advocacy.

  3. I am totally confused. My husband went to his cardio today and he said his pacemaker is working 100% of the time. Does that mean that is the only thing that is keeping him alive. His pulse was 60.

    1. Profile photo of Kristian Webb Post

      No not at all, if his natural heart rate was 50bpm his pacemaker would be working 100% of the time to keep it at 60bpm. If his pacemaker malfunctioned he would just revert to this heart rate. Obviously I do not know the actual details but this is an example of how 100% pacing does not necessarily mean a person is pacing dependent.

  4. My 94 year old mother, who is one of nine siblings, most of whom have pushed to about age 100, has atrial fibrillation.She had a Biotronik brand pacemaker installed in her chest last Dec 29. Prior to install, a ZIO’s 2 week monitor showed rates ranging from 34 to 167 beats.

    In discussion with him prior to install, I wanted the cardiologist to set the min. rate at around 60 beats, but he ended up setting it at 70.

    Now she ‘paces’ 92 % of the time.

    However, prior to her developing a-fib, (she ‘contrated’ a-fib as a result of b eing put on methodone as a pain management regime after a knee replacement surgery and her not knowing that she could not just quit the med ‘cold turkey’), she was almost always 48 to 52 beats per minute and BP of 110/70.

    My question revolves around my concern that maybe, maybe she should have her min. rate set at 60. This for two reasons that I admittedly presume here, (1) her historic rate before contracting a-fib and (2) her pacing now 92%.

    Is my reasoning sound?

    BTW: I theorized to the cardiologist before the pacemaker was installed that once it was in place, his push for AV node ablation might be rethought, in that I predicted that once the pacemker was in place, her heart would not, as it were, ‘panic’ and race up to such high rates in an over compensatory manner as it had prior when it ranged down to the 30’s.

    Recent reviews of beat data since install seem to confirm this, as now she only runs up to 120’s and occasionally 130 beats as max, with nothing in the formerly higher range occuring since install of pacemaker.

    1. Profile photo of Kristian Webb Post
  5. Hello everyone. I hear concerns about pacemaker long term effects. I have been pacemaker dependent for 23 years now. I have had 5 replacements over the years and have now been diagnosed with advanced heart failure. With complete AV block every ventricular beat has been generated by my pacemakers. I have maintained close to a normal life all these years thanks to fantastic doctors. But, now my EF has dropped to 35% in August, and now 20% today. The doctors removed my dual chamber and implanted a CRT-P, bi ventricular pacemaker. My question is: I still have both original leads from 23 years ago functioning. Impedance at roughly 50%. Could these old leads be aiding in the loss of pumping ability I’m going through. They say it’s left ventricular dysfunction. Loss of pumping ability. Note: I also have vasodepressor reflex. My bp drops extremely low (not medication induced) to ~68/43. I’m on meds to raise it throughout the day. What are your thoughts. [i was 26 when first implant was done. I am now 49. So not too old.]

  6. So do you know once your 100 percent paced have they said if you ever decrease your pacing. Do your lips and face twitch and your lips feel numb when you over exert. Thanks. Seems like once you get to a point answers are slow coming.

  7. A bout two weeks after I had my third defibrillator pacemaker placed I am kind of short of breath when I try to do anything just that mean they need to readjust the pacemaker Pacing

  8. Hi, my Dad suffers from advanced stages of congestive heart failure, renal failure and now his liver is compromised. Today I learned his own heart no longer beats, the pacemaker is keeping him a live by pacing 100%. He also is working all on the right side, the left side is compromised.How long can you live in this condition? He is being released from the hospital tomorrow and I am nervous for him to be home alone all day long. Please help. Please answer honestly. Thank you

  9. What is the battery life of a pacemaker that is pacing 100% of the time? Without the pacemaker my heart rate drops to the low 30’s.

  10. I would like to know what my mother will experience in a few weeks when her pacemaker battery dies. She is not a candidate for a unit replacement due to her poor health. She has been 100% paced for the last nine years (this is her second pacer, she crossed the RRT threshold on Feb 3 of this year). Will my mother be able to function well enough to care for herself? Will she need to spend more time sitting or in bed?

  11. If the electrical part of my heart has completely stopped functioning and I have had a pacemaker put in.
    .If my pacemaker stopped immediately does that mean I will die ..Seeing the electrical part is no longer firing .?..And how long can a heart actually keep alive and functioning with a pacemaker ?.Does the heart actually ever wear out after replacing the pacemaker a couple to three times?

  12. My wife just had a pacemaker that is a single lead into the ventricular chamber since they did an ablation to stop the erratic electrical pulse from the top of the heart. So she is now on 100% pacing. They set it at 90 bpm then yesterday they moved it down to 80 pbm. At 90 pbm it was steady as a rock. Now at 80 bpm it fluctuates and is currently hovers around 85 bpm. We have a finger monitor to show the bpm.
    Is this normal and why? Will being totally dependent on the pacemaker making the heart beat cause heart disease over time? She is currently 71 yrs old.

  13. My mother had an ICDimplanted in her in 2014 and was fine. But on June 13, 2014 she sufferred from barcardia (pulse rate was 40 /min) and ultimately passed away from Cardiac Arrest the same day at 9.15 am.Question is should not the ICD have maintained a reasonable pace in this situation

  14. my doctor said I was in a-fib all the time and I was pacemaker dependent. If my pacer is set at 70 beats per minute, and I am dependent on it, can it ever go faster at rest?

  15. I have a dual pace maker for the past 13 months but the 6th and 12th month check up revealed that dual pacing is less than 4 percent for both chambers , actually, less than 2 % for atrium while less than for ventricule. Should I still need to keep it in ?

  16. After an AV node ablation it was discovered I have no underlying or normal heartbeat. I am paced 100% , with bi vent pacemaker. When the pacer is tested and the capture level is turned down, I swoon as my heart stops. I have been told by my cardiologist this happens in 1-2% of AV node ablations. I go through pacer batteries much faster than normal, and is cause of great worry.

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