Pacemaker Technology Questions

Hey folks, two topics that have been on my mind as it relates to pacemaker tech. FYI, I have CHB so I'm particularly interested in that context. 

Wireless Charging

Are we starting to see this discussed/developed yet? If not, why? What are the major hurdles? Seems like you could reduce device battery size and only need a recharge every year? two years? and charging would be fast enough to be done with oversight at the EP office?

Leadless Pacing

I have seen some articles about leadless pacers, but are they very common? Are they pretty limited on the type of disease they treat? For instance, can they work for complete heart block?


Rechargeable/secondary cells have terrible performance...

by crustyg - 2021-06-27 13:24:17

There was a vigorous discussion about this exact topic within the last two months.

Rechargeable batteries have a terrible self-discharge rate, so they really aren't suitable for internal placement.  They also suffer badly from dendrite formation unless charged with non-DC, something that the Boeing engineers discovered (or so they claimed) with the very large lithium batteries in the 787.  And dendrites cause fires because they short-circuit a cell=>massive heating.

Leadless PMs: really not appropriate for simple CHB.  Also, no-one in the world currently has much/any experience of removing them, so what will you do when the battery fails?  For simple CHB (i.e. healthy heart muscle but failed AV-node) the ideal is to pick up electrical activations from the healthy SA-node and transfer them down to the ventricles in a way that doesn't produce LV-remodelling.  Difficult to see any benefits of a leadless PM for this.  This topic was also covered recently.


by AgentX86 - 2021-06-27 13:35:54

The first question comes up periodically and has a pretty simple answer. Wireless charging implies a secondary battery which, while getting better, have a short life and are very unreliable.  These are two attributes that don't go well with life-sustaining devices.

Wireless pacing is in its infancy. My understanding is that the current versions are used for sick sinus syndrome, even though they sit in the right ventricle. There is a new module, I believe, that intended for heart block. Last I checked it wasn't FDA approved yet. Not that I'd ever be a candidate, but they're too new for me. If you're interested, I encourage you to discuss it with your EP. He may be reluctant but he should be able to explain exactly why not.

I wouldn't think that CHB would be one of the conditions they'd be used for. They take some room in the right ventricle, which probably isn't a good idea.   I'm certainly not a doctor and know just a little about the leadless pacemakers and even less about your condition.

Leadless Pacemakers

by Marybird - 2021-06-27 16:08:12

I don't know anything about leadless pacemakers except what I read about them, so I looked up a couple sources to see what's out there currently.

The Medtronic Micra was touted as the best thing since sliced bread for those patients for whom it was suitable, with its advantages over regular pacemakers. Suitability was determined as having bradycardia and for whom ventricular pacing alone adequately addressed their problems. These patients had to have adequate sinus node function, therefore the Micra would not be suitable for those with sick sinus syndrome, or anyone who required, or who might potentially require dual chamber pacing.

Around 2020 sometime, they came out with the Micra AV, which is able to sense atrial activity, and coordinate its ventricular pacing with the atrium, more or less synchronizing both chambers. Theoretically this would be useful for patients with heart block ( even complete heart block, I'd guess), but like the Micra it depends on intact sinus node activity, so it would not be useful for people with sinus node dysfunction (SSS).

There's also apparently an Abbott/St. Jude version of the leadless pacemaker reportedly out there, the Nanostim, though it's hard to say if it's actually available or how often it's used these days. This model actually came out before Medtronic's MIcra, but there were reports of problems involving loss of signal, loss of battery power, problems with retrieval of the device, and it was recalled, this around 2016-2017 if I read the literature correctly. It's still shown on the Abbott website, but I'd wonder if it's really available these days, or how aggressively the Abbott people pursued the market for this product since so many patients would not be suitable candidates for leadless pacing anyway. . I'm presuming the Nanostim worked pretty much the same way the original Micra works, with single chamber ventricular pacing.

It seems to me that leadless pacing is still a work in progress, with a number of obstacles and issues still to be worked out. At this stage of the game, it looks to be that only patients with heart block ( those with intact sinus nodes) are suitable for this technology.

Here are a couple of linked articles on the topic, the most recent I could find.

doesnt make sense

by dwelch - 2021-06-27 21:05:16

Devices are quite tiny as it is a dual lead is dominated by the size of the connector more than anything.   It would take I suspect a day to a few days of charging at the drs office to get a years worth of charge.  The device would get hot enough to burn you quite badly unless you want to take a week of charging at a lower rate.  And I wouldnt expect the device to be smaller you would need a decent sized coil to have it not take a month to charge.  It is really not worth even discussing, I am glad I missed that discussion.  A new device every 10 years or so compared to days to weeks of charging a larger, more complicated, device.  Easy answer, new device every 10 years.  Being CCHB and doing this for decades already the devices have significantly improved over that time, each new device is better than the last.  thank god I didnt get one of those atomic ones (not because they were recalled, but I would be using ancient tech right now).  

Short answer, buy a wireless rechargeable phone the same day/year you buy your pacemaker. Your phone is much higher tech.  Only use the wireless charger, you cannot replace the battery or any other part of it, nor replace it until you get your next device.  Not a good plan. 

From the other answers it sounds like the other question doesnt make sense either, perhaps those are for patients of an age or with a condition that are not expected to need a second device.  CHB you are expected to need multiple/many.  All depends on where you start.  I am on number five and if I live long enough another 3-5 or so lets hope.  My last dual chamber device was dominated by the connector, the rest of the device (body, battery, etc) was super tiny.  My biventrical is bigger, running both lower chambers at 100% and now an even larger connector (well three connection interfaces of a standard size going back decades), but stil tiny compared to my first one decades ago.

I had these thoughs on my first device or two, but now realize you dont want to keep a device too long (many reasons).




this article answers a lot of questions about rechargeable batteries in pacemakers

by quikjraw - 2021-06-28 05:11:59

getting a new device

by Tracey_E - 2021-06-29 10:56:04

The assumption is always that we want the pacer to last forever, however I'm on my 5th and my current one is light years ahead of my first one so I look at replacements a little differently than most. When we get a new battery, we also get the newest technology. Maybe some day they will invent the most amazing pacer that lasts forever and perfectly fixes all of our problems, however that day isn't going to happen in any of our lifetimes so for now, I'm content to get a technology upgrade every decade or so.

As someone else said, leadless is in its infancy. Great idea, long way from being the answer for everyone who needs pacing. Rechargable isn't even to the point they are testing it in patients yet tho they are making advances. I was reading about one that works a bit like a Rolex, our movement would keep it charged. The one I'm most hopeful about wouldn't be any of these, but stem cell where the heart can fix itself and not need hardware. Again, tho, I don't expect to see that in my lifetime. Worth keeping an eye on, tho. 

Prof Stephen Westaby is worth a read

by crustyg - 2021-07-01 16:03:23

Paediatric Cardiac Surgeon with personal experience (through a patient) of the astonishing regenerative power of stem cells in the heart.

The problem with all predictions is that they cannot take into account the changes in direction made possible by discoveries that we haven't yet made.  For years, gene therapy was the Holy Grail of many inborn errors (e.g. Cystic Fibrosis), and then CRISPR seemed about to make this really possible without killing patients with horrible iatrogenic cancers and then an effective therapy (for some) cystics came along.

Sometimes it's just a long, careful slog (e.g. successful heart transplantation without immediate rejection) and sometimes a breakthrough changes the therapeutic landscape.  No consolation for those who fall by the wayside before then, of course.  I know that I'm incredibly lucky to live somewhere that pops a gadget into my chest and I'm 'cured', whilst watching contemporaries struggling with fatal 'benign' disease...

Nothing wrong with striving for something better: 'All Change comes from malcontents.'

Development likely slow…

by asully - 2021-07-01 22:44:10

Due to the "if it ain't broke don't fix it" mindset.  Like crustyg said it takes a lot of "unhappy" consumers to push for change, and the companies don't view the patients as consumers but the EP departments and hospital who purchase their products in bulk.  Commercial hospitals run the industry and unfortunately as long as it's cheaper and still works they will buy it.  Insurance companies also have to get on board, you will find that the latest and greatest medical devices aren't covered by many insurance plans.  They only want to cover what is "medically necessary" and are not concerned with new tech unless it means big savings for them.

You know you're wired when...

You participate in the Pacer Olympics.

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