VVI 40 from DDD


I have 2:1 heart block and a long PR interval

For most of this year I have been on DDD with rate adaptive AV.

the rate adaptive setting appeared to be the only way of me getting 1:1 pacing when exercising. This also included an upper tracking rate of 180bpm. Everything seemed fine no symptoms of anything even during my limited exercise events this year.

But this has meant I now pace 100% in the ventricles.

Last week after an appointment I was moved to VVI40. This was quite a surprise to me as it was effectively turning my pacemaker into a pure safety device nothing else.

I am going to see how this goes over the next month but has anyone been switched like this before?





by Gotrhythm - 2021-12-17 13:51:16

I understand the pacemaker mode VVI but don't know about VVI40. What does the 40 refer to?

And what do you mean, "turning my pacemaker into a pure safety device nothing else... ?"

All pacemakers are "safety devices." As long as contractions happen when they should, the pacemaker does nothing. For all of us, no matter if we're paced 5% or 100%, the pacemaker is there "just in case we need it."


Quality of life.

by quikjraw - 2021-12-17 14:05:55

The 40 the minimum ventricular rate allowed by the pacemaker before it starts to pace the ventricles, i am lead to believe.

So as long as my ventricles are activating above rate above 40 I have no support from the pacemaker.

So I won't black out but that's about it. I'll still be in 2:1 block above this rate so assume I will feel no better than I did before the pacemaker when above this rate.


by AgentX86 - 2021-12-17 14:39:45

I agree.  This is really odd.  I'd be asking a bunch of questions.  With a 2:1 block, at the lower limit of 40bpm, your atria would be beating at 80bpm, then slip dyssynchronous below the lower limit (if it ever happens). You'd have to have an atrial rate of 240bpm to get your heart to just 120bpm.  DDD mode equalizes the two. Odd but I'm sure there is a madness to this method.  I'd certainly want to understand it.

Quality of life

by Gemita - 2021-12-17 15:08:17

Hello John,

Firstly, how are you and your treatment for your Ankylosing spondylitis?  I do hope things are settling for you and you are getting some respite from your difficulties and that you are tolerating your new medication well.

It sounds to me as though you need to have a meaningful conversation with your EP about what this means for you.  Technically why was the mode changed?  Did he discuss it with you?  I note you have a long PR interval.  Is there a problem with the atrial lead or are they trying to experiment with ventricular pacing because you are not happy with pacing 100% in the RV and they want to see what your heart is capable of with minimum support?  A pacemaker set at 40 bpm would be miserable during daytime activity, unless your doctors feel your own heart rate is always well above this level during the day?

I thought VVI pacing was for single lead ventricular pacemakers.  Has your atrial lead been switched off or was it malfunctioning?   

I understand VVI pacing means 1) ventricular pacing and sensing  2) If no electrical impulse is sensed then your pacemaker will pace at your pre-programmed rate (of 40 bpm in your case)  3) if electrical impulse is sensed, then pacing is inhibited.

Pacing in VVI mode will result in dysynchrony between the atrium and ventricle and could lead to problems and to loss of atrial kick.  Are they still trying to determine the level of pacemaker support you really need I wonder?  

We were told VVI mode is primarily used in patients with chronic atrial arrhythmias which are not expected to return to sinus rhythm.  Have you developed arrhythmias John?  My husband is in VVI mode with his single lead ventricular pacemaker due to chronic Atrial Fibrillation with a slow ventricular response. He also has evidence of Mobitz II block and LBBB. He needs pacing to prevent ventricular bradycardia with slow AF.  Is it really the right mode for you though?

So it's not just me

by quikjraw - 2021-12-18 09:13:59

I'm glad it's not just me who thinks this is strange.

The letter from the cardiologist suggests this was a cardiologist lead decision not the EP. So I think his hands were tied.

I told them that I was very concerned and that I was very worried about this change explaining exercise etc but he appeared to have no other choices. 

Ive been preoccupied with methotrexate treatment and other ailments for a while and need to get back to understanding what else we can do to optimise my settings.

When on my exercise test my ventricles would not beat above 150 when my atrial rate was 180. The upper tracking rate was changed to 180bpm. However the letter says I could not mount a chronotropic response on the treadmill. This is clearly incorrect. I really do worry about their accuracy sometimes. These are fundamentally mportant points. If I couldn't mount a chronotropic response o would have rate response on but I haven't.

My treatment has been mostly unremarkable Gemita. I am now self injecting and there is no doubty joints feel much better but I had a series of joint steroid injections and I am convinced they did the job not the methotrexate. 

My abdominal pain is still present and I am now receiving a capsule endoscopy which is the final piece of the puzzle. I'm convinced I have inflammation in my small intestine.

I hope you and your husband are seeing some improvements since the last time we spoke.

VVI at 40 bpm mode

by Gemita - 2021-12-18 15:22:41

John have a look at the attached link below. 

It suggests VVI at 40 bpm is used for spontaneous ventricular sensing and inhibition of ventricular pacing;  recycling of the ventricular escape interval on each ventricular sensing;  device operating in sentinel mode.  But what exactly does this mean for you and what questions do your doctors want answered by this mode switch?  Why did they switch it when you were feeling okay in DDD mode?  Anyway the brief link might help to understand what they have done and help you to ask your doctors any questions.


I will private message you after Christmas with an update on our progress. We are both having online physio/consultations with our doctors at the moment and only time will tell just how effective these will be.  Cannot get my head around 'remote' care but that is the way it seems to be going.

Have a wonderful Christmas John and I hope your heart will not complain in VVI at 40 bpm mode.

Quality of Life

by Gotrhythm - 2021-12-18 15:25:19

I think I begin to understand a bit better why you said your pacemaker was only a safety device.

You're right. When it comes to settings, the issue is quality of life. You say everything seemed fine with the DDD adaptive rate. But you didn't say how you have been feeling since the switch in mode. Any changes? Do you notice any differences, either better or worse?

No, you are not alone in thinking this is strange. AgentX and Gemita are both more knowledgeable and can suggest better questions. My big question would be "Why?" And an answer of "The cardiologist said so," wouldn't be satisfactory. I would want to know what about my condition neccessitated the change and what the short and long terms goals of the switch to VVI were?

One point. Being paced 100% in the ventricles isn't significant in and of itself. The percent paced can go up and down depending on the settings. What you want are the settings--regardless of percentages--that give you the best quality of life.

Be sure that you are taking notes about how you feel and under what conditions so that you are ready to give good feedback on the difference the switch in modes has made for you.

I have 2,:1 block

by PacedNRunning - 2021-12-19 00:23:56

The tricky thing with 2:1 block is if you need it to pace you with exercise. You mentioned it only tracked you 1:1 with rate adaptive Av delay. That tells me you need it to exercise. I have exercise induced 2:1 block so we knew at a heart rate of 120+ I would go into 2:1 block. So we set the rate adapative delay to pace with exercise and back off under 120bpm. The best we could do was I had to pace 100% at 100bpm or higher. That equaled about 35-50% of V pacing. So do you know when you V pace or experience 2;1 block? I think they may have changed you because they want you pacing 100% but honestly like someone else said the settings should be based on how you feel not pacing % unless it's pacing you unnecessarily. I hope you find answers. I would be miserable at VVI 40 

Really useful thank you

by quikjraw - 2021-12-19 07:08:09

This sounds like an excellent compromise PacedNrunning.

They tell me very little to be honest.  I have to infer everything.

However, if it can support me whilst excercising but back off the support during rest or just sat at work that could really drop my pacing but give me a a decent quality of life.

I suppose my complication is my very long pr interval but I'm sure there are still options that do not result in 100% pacing.

You know you're wired when...

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