Voltage and pumping capacity

Does anyone know if the setting of the voltage is related in anyway to more or less pumping capacity?  Typically doctors like the lowest possible setting in order to increase the longevity of the battery.  So setting it higher would diminish the life of the battery.  A higher setting however,  if in any way related to  the pumping capacity,  might improve exercise tolerance.

I’m sure some of my brilliant pacemaker friends know something about this. Looking forward to hearing from you.





by AgentX86 - 2020-08-17 17:03:13

Sorry,  there is no easy way to becoming The Hulk.

A pacemaker only initiates the heartbeat. As long as the signal is "captured" (sufficiently excited) by the heart muscle, a higher voltage  doesn't matter. The pacing signal the blasting cap, if you will. The heart muscle is the dynamite.


by Tracey_E - 2020-08-17 17:49:02

The pacer tells the heart to beat. It's up to the heart muscle to do the work and contract. 

could be low

by marylandpm - 2020-08-18 07:55:26

  Make sure the voltage is not too low. My atrial voltage was low. It caused problems when I was active. It wasn't until a doctor that was good at looking EKGs  saw what was going on during a stress test I had that was in my records. I had complaned about exercising and finaly changed doctors. What a difference.  I will only trust a EP to change my PM setting.


by ldebaugh - 2020-08-18 09:59:06

I dont know if our issues are similar but I’d like to know to know more.  I’m also in Maryland. What was your original setting and how much higher was it changed?  What kind of improvement did it bring?   Perhaps you would like to pm (private message) me. 

Im 100% paced with a 50% EF.  Thanks for your comments! 




Let's be clear about this

by crustyg - 2020-08-18 11:06:48

Doctors do NOT use the lowest possible settings to prolong battery life - that is NOT the primary objective.  The primary objective is to use whatever settings reliably achieve capture (==electrical stimulation of the heart muscle), under all pacing conditions, in order to deliver what pacing impulses are required for optimum heart function.

Once the primary objective has been achieved, it would be foolishly wasteful to use more energy per activation/pacing output than is needed as this would shorten the battery life, within certain guidelines.  Normally, pacing Voltage output is 3 X minimum capture voltage (so if capture is achieved at 0.6V then pacing output would be set to 2.0V) so that there is some headroom if the paced lead's connection to the heart muscle deteriorates over time (usual cause growth of fibrous tissue which doesn't conduct electricity very well, or slight movement of the lead, less commonly partial lead fracture).

However, pacing output pulse width is also critical.  Just occasionally the pulse width that works at a low rate isn't quite enough for higher pacing rates - I think it's *one* of the things being tested when the EP tech drives HR up to something fairly fast at a routine check - often 120BPM. 

I wonder if that's what marylandpm has experienced, and might be going on here.  I see that Medtronic has a US Patent for automatic pulse width adjustment circuitry to compensate for reducing battery voltage to deliver constant energy/charge per pulse delivered, so clearly it's a well known problem.

Just so long as we dispose of the idea that there's a cruel cabal of EP docs and techs who could turn up our PMs and make us all into Colonel Steve Austin, if only they weren't so mean.

sweet spot

by dwelch - 2020-08-18 13:15:32

There is a sweet spot, not too high, not too low, just right.  They do want to go as low as they can within reason in that sweet spot to in theory add life to the battery.  Too high and the signal can echo and cause extra beats or cause belly bumps (muscles in your belly firing when it should just be your heart muscle), etc.  Too low and it doesnt fire the muscle and what would be the point of that, so there is a sweet spot, this is in part what they are doing when they do the interrogations, certainly the initial implant the few week chekup and the few month checkup as the heart scars over the tip of the lead and the electrical resistance settles in then they can make ideally final adjustments.  "back in the day" it took a good part of the first year or two to get me dialed in, some of it is semi-automatic now I am told.  

As stated above it just needs to fire the muscle or start the process the goal isnt a certain strength of contraction instead a contraction at the right time.



Automatic capture sensing

by AgentX86 - 2020-08-18 15:21:13

Just one data point regarding Medtronic's automatic capture algorithm, my EP turned the feature off in mine because he didn't like the answer. He said it's not uncommon for it's optimization to come up with the wrong answer.

I agree

by crustyg - 2020-08-18 18:51:32

I agree, Agent: we've had quite a few posts from folk who are clearly being disturbed by the daily automatic capture voltage calibration adjustment.  I'm very lucky in that capture voltage auto-calibration is not possible for my PM in the current pacing mode, and so far my atrial lead has proved very stable - but it's only been in for 15months.

I mentioned the Medtronic patent only to emphasise that pulse-width may need to change as well as pulse voltage.

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