Right Ventricular Auto threshold


I have a dual chamber PM in DDD mode ( R turned off) for exercise induced high grade 2 degree AV block. I'm not pacemaker dependent with intrinsic rate in the 50s. Of late however, I have been experiencing sensations of heart beats ( pulsations) over the chest or upper abdomen off and on but briefly lasting a few minutes at a time. No twitches. They feel like the usual RV auto capture tests that occurred every 21 hours in Boston Scientific Accolade, but they were not. The pulsations were regular, narrow complex sensed ventricular beats based on the 6 lead Kardia. I had my pacemaker intorregated 2 days ago, and everything checked out fine. Atria paced 68% and Ventricles < 1%. AV search + was 100 %. No tachyarrhythmias. Reprogramming involved lowering base rate to 55 and RV auto capture turned off to minimize sensations! Nonetheless I still experience the episodic sensations but no more RV auto capture sensations. My main question is how crucial is it to run the Ventricular capture tests daily in me with a Vpace  <1%? My battery life is still 15 years. Thanks for your opinions.


Right Ventricle "Auto" Capture - Is it essential?

by Gemita - 2023-09-21 02:03:08

Hi Rch, nice to hear from you.  I will "try" to answer your question.  I see that you are barely paced in your right ventricle and have 15 years battery remaining. Sounds excellent to me.

Since your technicians have already turned OFF your right ventricle “auto capture” setting, this tells me that it wasn’t essential to have "auto capture" ON. This setting can be safely set to “fixed output capture” instead if the daily auto tests bother us.

I was told by my technician that the threshold is the amount of energy it takes to make the heart contract. The output is how much energy the device is delivering to accomplish this.  If they set a fixed output they usually set it two or three times the threshold.   Our thresholds can change a little during the day.  If we have auto threshold ON that can save battery but having it turned OFF and “fixed” should not be a problem.  Hopefully other members can tell us more?

The sensations you describe are very common for me as an arrhythmia sufferer (sensations of pulsations/heart beats in the diaphragm/epigastric area).  In fact I call mine "diaphragmatic flutter".  I appreciate you are not having any tachy arrhythmias at the moment Rch, but I suppose you could still be feeling other intermittent slow rhythm disturbances or even nerve related problems from your implant?  


by Rch - 2023-09-21 19:40:52

Thanks Gemita. I got some private messages as well that it wasn't necessary to have the capture tests daily, and that once a year was sufficient especially when V pacing is <1%.

Hi Rch!

by PacedNRunning - 2023-09-21 20:42:19

I have the same diagnosis as you! Exercise induced high grade to 2:1 block.  That was difficult to diagnose.  I didn't look at your profile, but at about 12 mos post implant I started having the same sensation.  Except I called it thumps or continuous palpitations.  It can be one or two things. It can be pseudofusion beats which means your own heart and the PM are working at the same time. This will produce a narrow complex on kardia.  Purely paced beats on kardia will look like carrots (thats what I call them).  Second, it can be your own heart since it is narrow.  The pacing percent doesn't tell the whole picture.  The fix for me was to first extend the amount of time the PM paced to avoid the pseudofusion.  When that made things worse, they made the PM work sooner and shortened my AV Delays. That fixed the issue. :). I felt better for about 2 weeks and then it came back again.  Went in for another adjustment and again, fixed it.  This went on for 6 mos. I went from 40% paced to 100% in those 6 mos.  My AV block got worse. :(. At implant, my block only happened if my HR went over 130-140bpm. When I first developed those symptoms at 12 mos post implant my block was starting at 100bpm.  It just kept going lower and lower to finally 24/7. I'm now in CHB and have been for the last 3 years.  I've had my PM 5 years.  


I think you received your answer about auto threshold.  I have mine off. So annoying.  I had it on for years but at my recent battery change, I had them turn if off.  It saves battery but not significantly. 

You know you're wired when...

Your pacemaker interferes with your electronic scale.

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