Pacemaker not working?

Don't know if PacerRep or anyone else can help me out with this one. I went for my first little run post PM implant (17th Oct) today and when my heartrate got to 169 it dropped to 88. As I am a runner and I have only had the PM fitted because I was getting a 2.1 block when my heart rate gets to around 140+ my upper limit has been set at 162. Why then didn't it kick in when it has only gone a little over 162? I will fone the pacemaker clinic on Monday but any comments in the meantime would be appreciated.

15 Comments

2:1 block

by golden_snitch - 2013-11-02 03:11:14

Hi Pammy!

As Don already explained, when you have a heart block and your atrial rate exceeds the upper programmed rate, the pacer will go into a 2:1 block. It's a safety feature to prevent atrial tachy-arrhythmias from causing inappropriatly high rates in the ventricles. So, you'll need the upper programmed rate increased. However, it will still be possible that your sinus node exceeds that rate, for instance 180bpm, and when at the same time you are having a heart block, the pacer will again go into a 2:1 block. My pacer does this, too. When I go running, I usually start with an atrial tachycardia, so the atrial rate exceeds the upper programmed rate, and my rate drops from around 175 to about 90. Not sure, if there is any possibility to switch this safety feature off.

As long as you don't have the heart block, the upper rate doesn't matter, because no pacer can prevent a fully functioning AV-node from passing signals coming from the atria on to the ventricles. But as soon as you've got the block and are in a DDD(R) mode, the safety feature can kick in. Happens when I'm running, too, but only the first couple of minutes. Then the atrial tachy stops, and my pacer can take over 100% in both the atria and ventricles. I wear a Polar heart rate monitor and it's accurate. We have tested it on the treadmill and also with a holter monitor running when I was running.

Inga

Note to IAN

by Casper - 2013-11-02 04:11:33

Hi Ian,

Do us all a favor, please copy and paste the message Electric Frank sent you.

I'd like to see his comments, I'm sure there right up there with Don's and Inga's.

Thanks,

Casper

safety feature

by Tracey_E - 2013-11-02 05:11:51

The feature Inga mentioned can be turned off. I had the same problem. It's meant to keep our rate down during afib episodes. Since I don't have any history of afib, they simply turned it off. When they raise your rate, this should make it a moot point.

It paces exactly up to the upper limit, no more. The ten over may be from a previous discussion we had where I said ideally you want your upper limit set about 10 over whatever your hr gets up to with activity so you have a cushion. So, if you get up to 150, you want an upper limit of 160.

Glad to hear you are up to running again!

It's possible

by PacerRep - 2013-11-02 07:11:47

I would need to look at your settings to figure this one out. As stated above there are certain refractory periods that are built into the device .... which is just a fancy way of saying a bunch of clocks running at the same time. When your heart exceeds your upper tracking rate you will go into what's called a Pacemaker Wenkebach, this is where your heart does not beat 1:1 anymore, but may beat 2:3 or 3:4 or 4:5 etc depending on your clocks......Eventually it will reach a point called the TARP, it is here that you are now in a 2:1 block.

The bpms between your upper rate and TARP point is called your "wenkebach window". I find it difficult to believe that your window is only 6beats(162-168), that would not be very optimal programming. Dealing with upper tracking rates without compromising your refractory periods can be tricky business and to be honest....there are lots of rep's out there that don't know what they are doing. They can surely explain the situation to you and they may generally think they know what they are doing....but some of the programming i come across makes me wonder how the hell these people still have jobs.

Tell your tech that he needs to shorten your "TARP" for you....this can either be done by shortening your AVD or by shortening another clock known as "PVARP". There is always a compromise when moving your TARP point, so that's why I can't really give you the settings, there are too many other factors that play into this...if you conduct retrogradely, then that limits what we can do. There is only one pacemaker on the market that doesn't deal with this PVARP and TARP business, unfortunately that's not the one you have.

Good Luck
PR

I'll Start the discussion...

by donr - 2013-11-02 09:11:29

...At the upper limit, when the PM senses that your heart has reached it, goes into its own 2:1 control algorithm. Why? Because it doesn't want to try to drive the ventricles at a rate higher than they can function. Now, perhaps yours can function at higher rates than 162 - the PM doesn't think so because it has been programmed to act at 162. At that point, it only fires the ventricular contraction every other Atrial contraction.

Dunno how you are counting HR, but the numbers you cite all seem to be w/i the limits of accurate counting for a 2:1 rate drop.

Pammy: Since I wrote my comment, I've searched all your posts/comments to see how you determine HR. Nothing there to indicate if you use an HR sensor as part of your running gear. A finger at the wrist & a second hand are very poor for accuracy in counting. Even some sensors will have inaccuracies in sensing beats when you are PM driven - the PM spoofs the sensor.

How do you know whether or not the PM was pacing your ventricles beyond the magic 140? It may well have been doing so & you did not feel it. It sounds to me, since there was a sudden drop in HR, that your PM WAS keeping you going at HR's above 140, but when it got to the 162 it quit, just like it was programmed to do.

Don

It seems to me that......

by IAN MC - 2013-11-02 09:11:49

...... you should either keep your HR below 162 ( which is unacceptable for a young fit lady like yourself ) OR ask to have the upper limit raised to say 185 and see what happens when you run . The pacemaker , as Don implies, only does what it is programmed to do.

A very helpful member by the name of Electric Frank , who has regrettably left us , once sent me a Private Message with his thoughts on upper limits, the difference between Upper Sensing limits and Upper Tracking limits etc. When I unearth it, I will send it to you.

Best Wishes

Ian

Hi Pammy........

by Tattoo Man - 2013-11-02 10:11:59


..............are you using a Heart Rate Monitor ?. My one, a Cardiosport has regularly delivered some very skewed readings...not uncommonly half of what I know it to be.

Just a thought

Tattoo Man

heart monitor

by PAMMY - 2013-11-02 11:11:10

Hi to all above and in answer to how I know if my heart missed beats - yes I was wearing a heart monitor but also I had the symptoms of heart block ie slight dizziness and legs like lead and therefore had to stop and I had only gone about a mile! This was the problem I was getting before the PM and the reason for having one. I don't know how accurate the monitor is but certainly at resting pace it's accurate as I have timed and counted my beats myself and it has been the same as the monitor. I am sure that they will raise the settings to 180 as they were originally going to but then said try it at 162. I just thought it still allowed about 10 beats over.
Thanks Ian I would like to see Electric Franks thoughts on upper limits if you manage to find them.
Pam

Don't Scare ME PacerRep

by Casper - 2013-11-03 01:11:35

Oh No!!!!.

Don't scare me Mr. PacerRep, I'm always wary when a Pacer Rep comes in, I'm afraid they might not have the same know how, some of the hospital technician have.

But when I listen to some of your comments, you restore my faith in them.

I guess the lesson here, is to go with your gut instinct and if you don't feel comfortable with either the hospital technician or Pacer Rep, you can get some who you can trust.

Casper

PacerRep...

by golden_snitch - 2013-11-03 04:11:32

In my Sorin Reply you cannot program any refractory periods, they are dynamic and non-programmable. My cardio has looked into this, but no way to program them manually. What would you do then? I always go into that 2:1 block. My upper limit has been raised to 175, but it still happens. AVD is 140 at rest, 65 when exercising.

Thanks!

Inga

My problem too; now answered

by JerryG - 2013-11-03 05:11:26

I have a very similar problem and you folks have just given me the answer and I must try to get an appointment with my cardio asap.

My PM was implanted on September 17 and as I live on my farm in a private game reserve, I am 550km away from my cardio so I haven't had a follow-up visit yet. I have absolutely no idea what my PM has been programmed to do or not do, but at 66 years old I still work out for a minimum forty minutes every morning on my treadmill.

I cannot do more than walk very briskly and vary the inclines as I have other problems which prevent me from running but I still try to get into the aerobic zone (60% + of MHR) and easily succeeded prior to implant. My PM doesn't seem to like me getting over 100bpm per my Polar HR monitor. I reach ±100bpm and I suddenly drop rapidly down to 75bpm. I then slowly build HR up again from there.

I was diagnosed with Afib earlier in the year but this was successfully electro cardioverted and haven't had a problem with it again (normal sinus rhythm) so perhaps my cardio was too conservative with the programming he ordered.

The Medtronic Advisa MRI PM is supposed to have all the bells and whistles including rate response so I guess it is just a matter of having the unit programmed to my needs.

Thanks for all the support.

Thanks, PacerRep

by golden_snitch - 2013-11-04 03:11:13

When I start running, I usually end up with what I guess is an atrial tachy that exceeds my upper rate limit. And then all of a sudden my heart rate drops to half of what it was before, so a 2:1 block. Then it speeds up again, drops again. That can take several minutes, and after that the tachy seems to stop, and the pacemaker takes over with a steady 115-130bpm.

Inga

Golden Snitch

by PacerRep - 2013-11-04 12:11:21

You have the device I was speaking of that does not deal with the PVARP/TARP business. It works on a completely different approach.

I don't understand how you are going into a 2:1 block with this device...unless you mean your own rhythm is in 2:1 but the pacemaker paces your ventricles to maintain a 1:1 ratio? If you go into an atrial flutter or something like that...then I can see a 2:1 situation...but with something like that there is nothing any pacemaker can do...that needs to be controlled pharmacologically or via ablation.

You can program a refractory period known as PVAB in your device...but that is for something else and would not help a 2:1 situation.

RunBikePacer

by PacerRep - 2013-11-04 12:11:36

So ask your rep why doesn't he just set the sensitivity to 15mV on your device. 9 or 10 is huge but you can still program around it. This will cause your device to sense in the A and 100% pace in the V. But if your going 2:1 or having PVC's this may be a better option for you...it may not be. But if I understand correctly what your saying, that's what I would think about doing.

If you're only pacing 2-3% right now

by PacerRep - 2013-11-06 11:11:35

Then don't have him raise the sensing to 15mV. for some reason I thought you were already pacing a lot in the V.

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