ICD & AF

I posted recently (29th June, ICD Review) and I thought I would give you an update.

The ICD was adjusted on 25/6 and my situation was to be discussed at the group meeting. Since then I have had two letters. The first from the EP  saying: patient seen due to AF. Found to be in AT with a tachycardia rate of 100bpm with sudden drops to 55 with AP.  Then went back to AT. Reprogrammed DDI with VP/S at 55. Sent patient for a walk to assess RR, he felt better with it on. Lead checks all fine. End of letter.

Today I got a letter from my cardiologist: EP was able to induce a fairly inducible exercise related AT that is being tracked and conducted at a rate of 110 bpm. Interestingly his underlying rhythm was sinus rhythm and there was no trace of AF here which is a good thing. The DDI is now set at 60 and he has significant improvements in his symptoms. This basically means that he will still go into AT but his pacemaker will not track it at the high rates. Given this information there is no indication for proceeding with an AV node ablation. End of letter.

It has been four weeks since the adjustments and whilst not wishing to jinx things, I have felt pretty good since the review with a constant HR of 55/56. I thought I would share this you. I tried Googling DDI but couldn’t find an explanation, I would appreciate any comments. Take care everyone. 

5 Comments

I am glad they found Atrial Tachycardia and no Atrial Fibrillation

by Gemita - 2024-07-23 18:19:39

Graham Harry, that is really encouraging news and let us keep our fingers crossed that you will stay largely symptom free in your new DDI-R Mode = dual chamber, inhibited pacing with rate response enabled.

DDI mode allows pacing and sensing in the atria and ventricles and can also be inhibited if spontaneous activity occurs.  Atrial activity will not trigger ventricular pacing.  However, the pacemaker will pace in the ventricle if it does not sense a ventricular impulse within a certain period of time after atrial pacing.  Perhaps the following link will help to explain this mode:-

https://www.cardiocases.com/en/pacingdefibrillation/traces/pm/medtronic/dual-chamber-ddi-mode-0

With Mode Switching available today when you need it, I am not entirely clear why they are using permanent DDI pacing but since you are so symptomatic during faster heart rates, perhaps "steady" DDI pacing is less complicated than utilising Mode Switching?

In effect what your EP has done is to set your pacemaker to a non atrial tracking mode.  This prevents your pacemaker from tracking any high atrial rates (tachycardia) and conducting these to the ventricles, pushing your ventricles too fast.  Because you are no longer troubled by your high atrial rates, you have no need for an AV Node ablation.  Only time will tell how well DDI-R pacing will suit you, but on the evidence so far, the signs are all good.

I am sure you are relieved?  Thank you so much for that interesting update.

Beta blocker?

by Rch - 2024-07-25 00:10:15

There must be lot more to your medical history than what is presented in your bio. Since AV ablation was considered as an option for your symptomatic AT, I'm assuming your AV node is still functional. So, in that case, couldn't titrating up your beta blockers controlled some of your symptoms? 

About ATR mode switch, my Boston Scientific Accolade switches from DDD to VDI within 8+8 cycles into a fallback mode to 70. However, I am not sure why the mode switch is not DDI in my settings. 

Thank you

by Graham Harry - 2024-07-25 05:57:11

Thank you for your comments. I am on 10mg of bisoprolol which does seem to help as for my bio, I do have a long and complicated history of AF but I think I have covered the main points.

I have an ICD review next week when I shall ask about mode switching and whether my AV node is working. Anything else I should ask Gemita?

Just a few thoughts

by Gemita - 2024-07-25 09:51:34

Graham Harry, if you are still feeling well and are relatively free from symptoms with the recent change to DDI-R mode, you may not have any questions to ask at your ICD review next week.   However, if you are still getting symptoms I would make a list of the date, time, duration and symptoms you get, so that your team will know which settings might still need adjusting. 

Your own AV Node is no doubt still working but the DDI non tracking mode will result in AV dissociation when your atrial rate goes higher than the set rate.   You could ask what your set rate is to trigger AV dissociation?  It could be that you already have Mode Switch turned ON and that you only go into DDI non tracking mode and stay there during high atrial rate episodes?  That is what I would specifically ask about Mode Switch and your DDI set up?

Just to confirm, DDI mode paces in the atrium and ventricle, senses in the atrium and ventricle and the response to that sensing will be to either pace or to inhibit pacing, depending how fast your heart is beating.  For example, my Mode is switched to DDI when my atrial heart rates exceed 171 bpm, not before, but because you are so symptomatic at lower rates, you will no doubt have different settings.

Another question to consider asking is about your left lead and whether it should be turned on?  I know they said you don’t need it but why have a CRT device if it isn’t fully utilised?  At least you have that third lead already in place, so they could try it out at some stage to see whether resynchronisation therapy would help with your heart condition/symptoms? 

Sorry, there never is a simple answer!  

Very helpful

by Graham Harry - 2024-07-25 17:43:55

Thanks Gemita that is a very helpful post. I have not had any symptoms since the review four weeks ago I am delighted to say.  The letter says my pacemaker is set at 55 and the DDI set at 60. They said they went with a three lead set up as I may need the synchronisation in the future.

thank you for the information x

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