Medtronic PM "safe mode"

My history: 16 yrs ago I had a couple blackout episodes after strange deja vu-like sensations, one in hospital ER, where it was discovered that my heart slowed down then stopped for up to 10 seconds, before restarting. Doctors never gave me a reason why. Of course they insisted I have a PM implanted to keep myself conscious if another episode hit. So they implanted a Medtronic Sigma 300 DR and set the low rate for 50bpm, and 40 when sleeping. It's been great for all these years, and I've had no fainting episodes. Done phone checksevery 3 months and annual in office checks. Last week, a strange feeling in my chest told me something was wrong. I went to cardiologist office today, and was told by technician that the pm had gone in to safe mode, and was now not sensing, and was at a set 65bpm, ventricular only. She explained that even if I exerted myself, my heart would only beat at 65bpm, ignoring whatever signal my atrium would send. This disturbs me greatly! All these years the pm would only kick in on the extreme low side, and the device has been my comfort so to speak, and now it's "taken over" full control, so that I feel exhausted even after a night of sleep, and have to stumble through a work day. I evidently can't get in to see the cardiologist to consult for about 2 weeks, and only then can I get scheduled for a replacement. So I'm reaching out to you! Is this pacing mode safe? The technician said that the battery in this mode will last approx 6 months. Have any of you had to deal with this safe mode of constant 65bpm pacing, and drive and go to work, etc? Sorry for the extended post, but this depresses me and scares me at the same time. Any help would be most appreciated.

4 Comments

safe mode

by zawodniak2 - 2017-03-01 23:09:11

Same thing happened to me when my pace maker was ready for replacement.  My advice is to limit your activity as much as possible until you get your replacement, otherwise your body will degrade into a fatigue mode that will be slow to recover from.  65 bpm is sufficient for basic body functions, but not much more before you will really feel dragged out. I would advise you to insist on some urgency with your providers.  But you will be fine, now that you know what is going on.. The safe mode is designed to preserve battery life until replacement.  I hope you do't have a physically demanding line of work..

                                   Rodger

Re

by Sporter65 - 2017-03-01 23:19:43

Thanks Rodger... I still am confused about the "VVI" mode that Medtronic's website says my model reverts to, since the technician today said the pm now ignores the hearts natural signal, yet Medtronic says VVI suppresses its ventricular pulse if it senses a natural ventricular beat, which would imply that if I exert myself and the heart naturally signals, say, 85 bpm, then the heart will beat that fast, just won't go now below 65 resting, so that when I'm asleep, instead of a more common 45 bpm, I'm getting 65. I'm confused, and some phone calls are in order I suppose. Thanks again for the reply.

VVI mode

by BillH - 2017-03-02 00:58:19

The tech is not right or at least did a poor job of explaining.

It all depends on what you undelying problem is.

If you have a complete heart block then the ventricle will not see any atria pulses. In normal mode the PM will sense the atrial pulses and if it does not see ventrical then it will pulse the ventrical and it tracks the rate of the atria.

With sick sinus syndrome the atrial will not pulse fast enough at rest and/or the sinus node does not increase during exercise. In that case the main function of the PM is to monitor the sinus and pulse it as needed. Normally then the ventrical side of the PM as the atria pulse will automatically trigger the ventricle.

It is not unusul for to have some of both.

If you sometimes atria pulse of greater than 85 and sometimes they get through to the ventricle then that would override the PM.

safe mode

by dwelch - 2017-03-13 14:07:42

Facing pacer number five in a few weeks.  I have had two go into safe mode, the first I was young (mid 20s) and very active and didnt notice it.  The other one that did that I did notice a lot more used to climing the stairs between floors and work and would struggle with that since the pace never changed, so used the elevator.  

Not to concern you but it is to preserve the remaining battery, you should get months out of it in that mode, that is kind of the point, so flat rate 65 for however many weeks until they can get you in, just take it easy until then.

Yes it is a very strange feeling, and your breating/body will remind you that you cant exert too much.

You know you're wired when...

Your ICD has a better memory than you.

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