Pacemaker battery replacement

My dad is past 7 years on his first pacemaker battery. Every week we get an emailing report from the hospital showing the complete health, status and events on the device. Around October 2022 it showed 6% battery, 3 months remaining on the reports. Since then it has slowly made it's way down to "Battery is at 1%, <3 months remaining". It has stayed at 1% for over 3 months. <3 could mean anything from 1 minute to 2 months and 29 days. The device rep that is responsible for reading the weekly reports has several times comfirmed we cannot schedule the battery replacement until the device gives an ERI message. The only thing I see on the report is Battery Status: MOS. Is this normal for the battery to ride at 1% for this long? What does MOS actually mean? It's a Boston Scientific pacemaker. 


Low fuel warning

by AgentX86 - 2023-05-09 12:44:43

It is normal that they won't replace the pacemaker until ERI (Elective Replacement Indicator). You don't state the manufacturer or model (it can matter some) and mods but it is ERI that signals that the unit should be replaced.  In general, the unit should be replaced within three months of that time.

You don't state the reason for your dad's pacemaker but most (high percentage) of pacemaker patients will live fairly normally after the battery is completely depleted but they may not feel well.  There are several "natural pacemakers" in the heart that can take over if the pacemaker failed completely. Again, dependent on the users condition.

There is no reason to worry, waiting for ERI.  As I said, even then, you have three months for a replacement. Given a specific manufactuer and model may turn up some more information.



Battery replacement

by piglet22 - 2023-05-10 07:16:02

The lithium "batteries" or cells in pacemakers have a sharp cut-off curve when they get to depletion. They have the advantage of high energy density and a well characterized lifetime curve. Hence the popularity in a load of items from EVs pacemakers. The pacemaker type of course isn't rechargeable.

I went through battery failure and don't recommend it. This was despite close 3-monthly monitoring at the clinic.

The cardiology people can and do get it wrong.

You might need to be prepared for unusual symptoms. I was sitting at home one January evening when I noticed my left pectoral and upper arm muscles twitching. As it didn't stop and was at the same rate as a heartbeat, I put two and two together and guessed it was the PM. After some phone calls, the call handler arranged an ambulance. The out of hours physiologist turned up at midnight. I had been admitted at 7-pm. The ambulance people including a senior mentor hadn’t a clue what was going on and one said a PM couldn't twitch a muscle.

The physiologist said the battery had gone so low that the PM had changed mode. She raised the pacing voltage and that stopped the twitching but was rapidly depleting the battery voltage. The PM was changed later that day.

I never got an explanation for the twitching. I have seen on Google that some PM's use muscle twitching as an EOL (End Of Life) alarm. Clearly, the pacing pulses from the generator were going somewhere where they shouldn't. From an electronics point of view, it might mean that the lead-generator circuitry had changed and the screen or body of the PM was now at pacing polarity. This was well before home monitors and phone apps.

The annoying thing was that despite all the monitoring, what should have been an elective procedure with a date and time to get some things together, turned into an emergency.

Luckily, I was at home. I was on my own, but still had to think on my feet. Had it been in an aircraft halfway across the Atlantic, it would have been a different matter. You could say it would be daft to travel far under the circumstances.

For lot's of reasons EOL is not a precise science, but I can't help that suspect that this was a case of cutting things just too close.

One thing they might do at replacement, depending on your father's condition, is get him ready for external pacing. They did it for me but it wasn't needed. It would have been a lead up through the groin. Obviously, there is going to be a short time when you are disconnected from the old PM and the new one put in place. To be honest, with so much going on, I didn't notice what my heart was doing.

Good luck.


Battery replacement

by piglet22 - 2023-05-10 07:24:24

I forgot.

I stand to be corrected, but battery replacement is a euphamism for whole generator replacement.

I can't think that they take the old one out with all the gore attached, now un-sterile, fiddle around pulling the PM apart, get the old battery out, change the seals etc., sterilise it and put it back.

My cousin insists that her mother, my aunt, had the battery replaced and it remains a point of contention.

replacement time

by Tracey_E - 2023-05-10 08:21:49

I'm not sure about Boston terminology but it sounds like it's less than 3 months to ERI (elective replacement). At that point, it should still have another 3 months of being fully functional. After that, it will go into conservation mode and have limited function for another 3 months. No insurance will cover it before ERI. Some insurance won't cover replacement until it the second mode. At that point, it paces at a steady 60bpm so we are safe but if we pace a lot, it won't feel good. 

I am on #5. I've had them say <3 months for as long as a year. As long as they are keeping an eye on it, it should be fine! It's not going to suddenly stop, there is a generous cushion once it hits ERI. 

replacement time

by Gemita - 2023-05-10 09:29:04

You have already received helpful comments.  Regarding MOS, I did a quick search and found the following:

See under 3.2.  Battery Status box to see if you can make sense of it?   It would appear that MOS code = less than 10% battery remaining to ERI for IDCO battery stutus, but do follow up with your father’s medical team for his particular model of pacemaker, particularly if he is showing worrying symptoms at any time.


by AgentX86 - 2023-05-10 12:46:42

If I had to, I'd guess that the twitching was caused by a switch from bipolar mode (pacing pulse between two conductors in the tip) to unipolar mode (lead tip, across chest (lungs) PM case). This isn't supposed to cause any problem (my LV lead is set unipolar) but it does in your case.  The twitching was a convenient accident.

Are you PM dependent?  Escape rhythm?  If you do have an escape rhythm or you have SSS without pauses (who has that?), you would have been perfectly safe, if feeling pretty bad or unconscious, for a good while. Pacemaker replacement is rarely a life-threatening emergency, even if the battery goes completely flat.

two of five

by dwelch - 2023-05-14 21:00:08

at least two of my five or four am on number five had gone into ERI.  Talking to the doc looks like insurance companies are already requiring or will start requiring that you cannot have replacement until you switch over (compared to the good old days).    

Even months is not very accurage, until it says weeks or switches over, the battery estimate is not good, do not get worried about it.  

There is plenty of time after it swtiches over.  The device continues to work and pace for a fixed rate.  So you will get tired easy and such, which is probably by design to get folks that are active to think, "hey someting is wrong I need to see the doc".

Yes, everyone says "battery replacement" but the whole device is being replaced, open the pocket, release the leads, plug them into a new device, close the pocket, go home.

Lawyers unfortunately likely will not let you keep the old device, I have my first three, but not number four and likely no others.  (for anyone who thinks that some how they are cracking the case and soldering in a new battery).  You get 10 years new tech in the new device from the battery savings to usually a smaller device, more features, etc.

The home stretch can be frustrating, my first to devices it was a 3 year wait, each doc at that time had me come in more often (no phone box, home monitor, etc).  Again with the way the insurance is now you cannot just schedule a replacement now, back in the day you could be doing that right now, scheduling it for something convenient for you and your father or working around some family event, etc.


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