Effect of Atrial Pacing

Interesting one for you technical types. Using my ECG together with the Care Link I can run a high resolution strip and watch the the effects as the Care Link programs pacing through the test.

At one point in the test the pacer is programmed to Ap-Vp at 85 bpm. During this time I can see the pacing pulses varying in amplitude so I suspect this is when the pacing voltages are tested.

Now the interesting part. At the end of this test the pacer is programmed to As-Vp (for my AV block). On the first beat the natural atrial P wave doesn't occur so the pacer issues an Ap-Vp to cause the beat to occur at the Lower Limit. On the next beat the P wave occurs at the natural rate and As-Vp pacing starts.

After a few beats the pacer is programmed for a short burst of Ap-Vp at 100 bpm and high voltage.When this ends and the pacer is set to my normal As-Vp the same skipped P wave happens.

So something about pacing my atrium causes it's natural rhythm to be upset for one beat after the atrial pacing is removed. I checked this from a number of records from over the years and it always occurs. I also rerun The Carelink and watched my ECG on the computer. (I have a way of seeing the pacing pulse and P,R waves separately as bouncing bars). The strange and often disconcerting sensations occur exactly at the time of the missing R wave.

So here is my thought. some of us have found that having RR on when we don't need it produces uncomfortable symptoms. The E.P.'s cardios, and even reps will say there is no problem because the RR will only take over when needed. However, what I just observed showed that the switch over from Ap to As can produce a transient delayed beat which produces symptoms. I have been assuming that it was the increased rates (85 & 100) during the test that was the source of the symptoms.

By the way I didn't phone in all these Carelink tests. I verified with the Medtronic rep that there was no problem with my running them for my own use, and just to keep in mind that they do increase battery usage slightly.

So, what do you experts think?

frank

16 Comments

This is what I love about PMC...............

by Tattoo Man - 2013-03-23 02:03:02


......................reading stuff that I have ABSOLUTELY no idea about.

Frank, as a superstar in the PMC cosmos..I am in awe of your grasp of all that Tecchie stuff.

Me, suplicantly at your Majestic Feet...I can only admire you from afar.

TM

That's what I depend on!

by ElectricFrank - 2013-03-23 03:03:30

Plenty of techie stuff interspersed with big words and wa la!

There's only one problem. During my teaching years I always insisted that if I couldn't explain something in a way that students could understand, then I likely didn't understand it myself.

LOL

So I will put it simply. I think I found another reason why RR can be uncomfortable. How about that O great one from afar?

frank

pacing

by Brenda Price - 2013-03-23 08:03:59

Does everyone not have their RR on. I have been 100% paced for 24 yrs with RR always on.I am aware sometimes at noc when the care link cks.

You'r ekg machine did you build it?

I always enjoy you'r post and learn from them

Junctional

by ebfox - 2013-03-23 11:03:20

Hey Frank,

You are on a different level than most of us. Do you think that you might be jumping from sinus to junctional? Back when I was pacing, every time we did an interrogation (with reams of paper) my EP would go through in great detail and usually he would say something to the effect that the PM was being fooled-

Would be nice to have a 12 lead EKG instead of a 2 lead-

EB

RR

by ElectricFrank - 2013-03-23 11:03:58

The only reason for RR is to replace the persons natural atrial pacing. Usually the diagnosis is Sick Sinus Syndrome. For the many of us with simple AV block it isn't necessary, and actually can cause unpleasant symptoms. Pacemakers come from the manufacturer with RR enabled, and many docs don't bother to turn it off if the patient doesn't complain. It's sort of a implant and and run approach. There have been a number of folks here on the forum who have had good results having it turned off if not needed. The two main disadvantages to having it on if not needed are:
1. Inappropriate increase in heart rate in situations where we are being vibrated or bounced around. For me it was the jets in my hot tub, and 4 wheel driving on rough desert roads.
2. Competition between natural pacing and the
RR.

Now I've discovered a potential new effect.

I'm a biomedical engineer and designed biofeedback equipment for years. So when I received the pacemaker I modified a channel on the biof to handle ECG. The beauty of it is that I can expand the display to see details that the medical ECG's can't handle. I can put the cursor on a feature, hold down the mouse button, and read the time to other feature in milliseconds. Cardiologist's have used pattern matching for decades and depend on having the ECG trace shown as those very small traces. Researchers use more sophisticated displays. The Medtronic rep knew just what I was doing when I showed my to him.

frank



Frank...............

by Tattoo Man - 2013-03-24 07:03:10


.............................you have , for a long time been a real Hero for Little Guys like me.......

But.......Zyphoid ??

When did we go into Cyberspace and start to get angry with ExtraTerrestrials...?

I have always got on really well with the Zyphoids,...my Christmas card list has a bunch of them.

My good friend is Zeke Zyphoid,...drives a buggy,...wears overalls,..dont have a phone....

Cal is a fair way from Penn..

Time travel is clearly better developed round your way

TM

Pacemaker fooled

by ElectricFrank - 2013-03-24 12:03:58

In my case I have normal sinus rhythm which is easy to see on the ECG. So when the Carelink is running the forced atrial pace at 85 it's simply beating the sinus pace to the punch. (at the time of the test my natural rate is around 75). Then when the atrial pace is stopped my next sinus pace even misses the Lower V Limit of 55 so the pacer adds a v-pace. It's a very reliable pattern whether returning from 85 or from 100bpm.

My suspicion is that it has to do with the different re-polarization after a paced contraction. The pacemaker inserts the pace at a single point on the heart wall where the sinus pace is more spread out.

Interesting! I have fun with it even thought I'm not a "trained" EP.

I'm not really sure what I would do with a 12 lead. Even with my 2 lead plus ground I don't use any standard placement. I use one active lead on my upper chest near the pacemaker, and the other just left of the ziphoid process. I've found this gives me the best P & R wave along with the pacing spikes.

frank

Frank: Ya shoulda...

by donr - 2013-03-25 02:03:55

...stood in bed!

That was BAAAAAAAAD!

Loved it, though.

Don

Frank...........

by Tattoo Man - 2013-03-25 03:03:00


...............................do you mind, Old Chap, that I insist you DO wake up every morning.

It will be a very sad day for PMC when you dont !

TM

Don

by ElectricFrank - 2013-03-25 03:03:14

What do you think of my original post in this thread. Things got side tracked! You are one of those here that know enough about it to not be intimidated.

frank

I agree

by ElectricFrank - 2013-03-25 03:03:24

It would be a sad day for me not to wake up. My wish is to be present when I embark on the Big Final Trip with enthusiasm, but that is another story.

frank

Frank: I am remiss...

by donr - 2013-03-25 05:03:14

...that I did not respond the night it appeared.

I was armpit deep on a tall giraffe in hungry crockagators all trying to eat me alive w/ my stone etching business.

I finally got around to reading it & all the subsequent comments, including those that made sense.

Ever since you first described your High Bandwidth ECG machine, I've been thinking at the wonderous details that heart researchers might find - both to explain existing puzzles & to open up new, unsuspected details of the heart's electrical functioning. I think the everyday cardios are not really looking fwd to that day - they have enough troubles explaining what they see now. It will even further blow the minds of the non-cardios who must look at the outputs of ECG devices.

Actually, your device is but an extension & expansion of bandwidth of using an index finger on an artery & counting beats while watching a clock. Looking at its niche in a historical study of EP, it is but the next step forward for inquiring minds who want to dig deeper into why our hearts do what they do.

What intrigued me most was your description of what YOUR heart does when switching between modes under the control of your PM. I sat & cogitated over those unusual rhythm patterns w/o coming up w/ an explanation.

I was constantly drifting in thought into what a heart does during its own refractory periods & kept trying to relate it to a discussion thread that took place based on a thread started by an Iowan woman in Cedar Rapids, Ariela was her name, I believe. Boxxed added a complex discussion of blanking/inhibition to the mix that initially soared over my head & went SPLAT!!! against the wall behind me. I was exploring mentally in an Einstein type thought experiment what the relationship between changing HR rapidly - like from one beat to the next - & refractory processes was. Matching up native (intrinsic) refractory periods & the PM programmed periods & seeing if there was an overlap that would have precluded either the heart or the PM from putting out a P wave, thus causing a completely missing beat. I think if such a thing is the cause of your artifacts, that it would ONLY happen when the PM was running in a fixed rate mode, as opposed to adaptive where it matches its output to coordinate w/ the intrinsic functioning of the heart.

I finally figured out why I could never find the PM spikes in all the ECG's I'd seen. I never knew what to look for & the bandwidth just was not there to allow the spikes to show up in the traces. In my book, it will be a great day when the cardio business gets higher BW devices as a matter of everyday business.

No, I am not intimidated in the least, but you have posed questions I cannot give you decent answers to.

Don

You got one too old man

by ElectricFrank - 2013-03-25 06:03:44

The ziphoid is a little bony thing at the lower end of the sternum (you have one of those too.) Or do they remove it when they crack your ribs open to overhaul your heart (I hope you have one of them).

Now I don't have a Nottingham, but maybe Nottingribs.

Guess I better go back to bed before I get in trouble. I woke up around 1:00AM here and got up for a spot of green tea.

frank

I think I see what can happen

by ElectricFrank - 2013-03-25 09:03:10

According to the Medronic ADDRL01 manual, with RR active the pacemaker tracks the faster of the intrinsic
atrial rate or the sensor-indicated rate.If the intrinsic rate is faster,the DDDR mode provides atrial synchronous pacing; otherwise,AV sequential pacing occurs at the sensor-indicated rate.

So if the sensor rate is higher than the intrinsic rate you would have the same situation the one I described during the Carelink sequence. Now if the person stops or slows RR type activity the sensor rate may fall below the intrinsic in which case the pacer switches to it. At the switch over you have what I see on mine. The only difference is that in my case there is only one switchover. With the RR in control there may an uncertain time when multiple switches take place.

Hmm.

frank

Both of youse guys...

by donr - 2013-03-25 09:03:46

...are already in trouble!

Ziphoid - Zyphoid - Xiphoid. Maybe some day we'll come to an agreement as to how it should be spelled.

Thank God for small favors that the heart is not located in the vicinity of the coccyx! I cannot imagine what kind of exchange we'd have over (or under) that little inconsequential piece of anatomy.

Think of the problems we'd have w/ the PM's & processes on a Vulcan - who has TWO hearts - & green blood. Yuck!

Sheeesh! I'm going back to bed, also; & it's 8:30 AM here, w/ the Sun up - I think.

Don

Thanks, don

by ElectricFrank - 2013-03-25 12:03:35

It would be much easier if the heart was located in the vicinity of the coccyx. To improve blood flow we could take Oxy-coccyx-tin.

That's bad! I shouldn't have woke up this morning.

enjoy,

frank

You know you're wired when...

Your kids call you Cyborg.

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