Heart rate rapidly dropping

I'm 40 and had a Medtronic Adapta dual chamber pacemaker placed in May for 2nd degree AVB. I was doing good the first couple of weeks and then developed palpitations when my heart rate goes over 80 (which it is almost all the time) and shortness of breath with minimial exertion, like one flight of stairs. I have seen my EP dr and 2 cardiologists, and I have been talking with my pacemaker nurse daily for the past 10 days. They tell me the palpitations are me feeling the pacing because my intrinsic SA rate is elevated @ 90 and that because of the elevated rate I'm also SOB. Today I had a stress echo and 4 minutes into walking on the treadmill I became SOB and very close to passing out. My HR was at 120 and suddenly dropped to 60. My cardiologist and my pacemaker nurse talked and they are telling me the pacemaker is working the way it is supposed too, that it is due to the 2nd degree heart block. So tell me how can it be normal for my heart rate to go from 120 to 60 in one heart beat? They say the only way to fix it is to lower my intrinsic SA rate by increasing my beta blockers, which we have already done 2 times in the past 2 weeks, or to pace me all the time. If any one has any suggestions please feel free to offer them. I have to get this figured out.

My pacemaker settings are as follows:
Mode AAI-DDD
lower rate - 40
upper racking rate - 160
upper sensor rate - 130
ADL rate - 95
rate response - on
ADL restrictions - 3
exertion response - 3
Activity acceleration - 30 sec
Activity deceleration - exercise

Thanks in advance for any and all help.

9 Comments

asfasfasf

by boxxed - 2013-08-01 07:08:12

They may have you in AAI-DDD because they are trying to promote intrinsic conduction and reduce RV Apical Pacing. RV Pacing isn't that great for you and alot of doctors try to minimize unnecessary RV pacing as much as possible. That's why their second option they told you was to have you pace 100% of the time.

This doesn't sound like Upper Rate Behavior, with the poster going from 120 to 60 considering that his Max Track Rate is 160.

This is just an uneducated guess, but it sounds like it's because of MVP. It's the name of the AAI->DDD function for Medtronic. St Jude's equivalent is VIP. Sorin's is SafeR. What all of these do is to let try and let your own heart do the work for a beat or two. It'll test out whether out whether or not you block. If you block X amount of times in a row, it'll switch immediately back to DDD and wait a bit before it tries again. This may be the sudden 120->60bpm drop that you are feeling from time to time.

asfasf

by boxxed - 2013-08-01 07:08:32

It's not uncommon for people to have rate-related block. They may conduct pretty well @ 60bpm from the A to the V, but when your HR elevates, you may end up blocking more. This can happen with some people. It may be why you notice the blocking more on exertion.

Again, just guesses,

asfasf

by boxxed - 2013-08-01 07:08:39

Re-reading my post I don't think I gave enough context. Let me get this out of the way and disclaimer that these are assumptions from an uneducated guess.

The reason why they're letting you block down to 60 every once in a while is because they want to keep your Pacing % low. That's why you have MVP (AAI->DDD) on. They want to avoid 100% pacing if it's unnecessary. So right now your pacing percentage may be anywhere from 40-80%. You're conducting on your own (presumably) half the time. The other times when you happen to be in AAI at that very moment, you block for a few beats before it switches back to DDD.

Again, these are assumptions based from guesses.

Are you sure Rate Response is on

by Grateful Heart - 2013-08-01 09:08:01

If RR is on your mode should read DDDR, the R at the end is for RR on. When the R does not show, RR is off.

It sounds like that is why your HR is going into a 2:1 block when reaching your upper limit....120 to 60. It doesn't feel good when that happens right?

So double check on the RR.

Hope that helps, good luck.

Grateful Heart

Huh ?

by Duke999 - 2013-08-01 09:08:38

The stuffs donr and boxxed talked about is quite advance for me. I got a lot to learn. Thanks for sharing.

Duke

Thanks

by rnff2 - 2013-08-01 10:08:29

I had a feeling you all would be able to shed some light on this...Thanks alot. I have learned so much. I'm an ER nurse and have never thought about pacemakers being so involved, the doctors make them sound so simple.

Greatful Heart - you are so right about it not feeling good when you heart rate drops...I don't think I have ever felt like that before...and hope to never again, it was the worse feeling ever. My under lying rhythm is 2:1 block...and the block increases as my rate increases, as do my symptoms.

Donr - my Mode Switch is ON. I am on Lopressor, have been for a long time we have increased it 2 times in the past 2 weeks with little results, I was instructed to increase it again today.

boxxed - After talking with my PM nurse today you are correct..good guess. They are concerned because I am V-pacing and they want to keep it to a minimum. I am V-pacing 47%. I have yet to pace my atrium. My underlying is a 2:1 block (came on suddenly in May and took me 2 ER visits and me insisting to the ER doctor what it was, it was hidden in my t-wave) and it worsens with increase HR, I had a myectomy in 2009 and have HOCM. I also feel myself pacing, thus the palpitations. The SOB worsens with activity and increased HR. My HR is 30% in each the 70's, 80's and 90's...and no change with the increased beta blockers. They tried to change the mode about 10 days ago with no success and put me back to the AAI-DDD. They state I don't need the rate response since I have my own intrinsic SA rate.

I just know that something has to give...I can't stand being on high doses of beta blockers because they exhaust me and I can't run around with my rate bottoming out on me like that, I can't walk up the stairs let alone go back to exercising. The plan is for the pacemaker to be interogated while I am on a treadmill and adjustments made at that time to see if we can fine tune it. I am waiting for a call back for that and I'm supposed to send another reading on Wed. I'm figuing out this isn't as easy as they made it out to me when that put this thing in me.

Thanks again!!!

Hold on there a minit...

by donr - 2013-08-01 11:08:10

...Your PM settings miss the common sense test!

AAI-DDD does not make sense when applied against your diagnosis of 2nd Degree AV Block (AVB).

Let's review the bidding on MODE. A= Atrial, D= Dual, I= Inhibited, & as Grateful pointed out, R=Rate Response being turned ON.

Atrial pacing gets you nowhere when you have an AV block. The signal just does not get to the Ventricles due to the block.

IIRC, DDDR is the common mode for AVB pacing - The PM senses what the ventricles are doing & paces appropriately if there is no indication that the ventricles will function on their own at the appropriate time. What is the % pacing for the Ventricles? That is a critical piece of data for determining why you may be SOB, etc.

Also, you have not reported whether the MODE SWITCH is ON or OFF. If it's ON, a switch to the AAI mode would be counter productive, were it to happen.

In your first post, you reported that they were putting you on Beta Blockers to slow your HR. Did it work?

Your intrinsic rate also seems high at 90 BPM. That's almost in the range of A-Tach. Especially w/ a base rate set at 40 BPM.

Another setting that bears looking into is your ADL (Activities of Daily Living) rate is awfully low - very close to the intrinsic rate you reported. It's possible that w/ the low (40) base & the 130 USR generating a low ADL that your PM is making you function at the ADL rate.

I agree (For what THAT is worth) w/ Grateful that you are functioning at 2:1 pacing because you hit the upper limits for Ventricular pacing.

These are all questions to broach to your Cardio for discussion.

Pacing 100% will NOT slow down your HR. the only way to do that is to so load you up w/ beta blockers you become a zombie & then use your PM to raise your HR to a reasonable number.

You indeed have a complex problem. Wish you the best.

Don

Wish you'd...

by donr - 2013-08-04 10:08:38

...told us all the info in your last comment in the original post.

Would have made all the difference in the world in what I said.

Don

Wish you'd...

by rnff2 - 2013-08-05 04:08:39

I'm sorry, I didn't understand or know alot of the information I was giving you in my first post. I also spoke with my pacemaker nurse after my first post and she was able to explain alot more to me. So with the information the forum provided, what my nurse provided and what I looked up online, I was able to give you more information after my first post. Sorry, I'm still new at this pacemaker stuff and trying to figure it out and understand it. They don't tell you when they put them in how complicated they really are.

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