Calling for people more experienced than me

Hi all, I am 2 days post op and no major complications at all so far and pain has been fairly minimal. I've got a dual chamber pacer set to DDD to treat my CCHB (HIS BUNDLE PACING). My consultant did explain this too me and I thought I'd understood it but maybe not so if anyone has the same condition and can explain it better than I then please do:

Am I right in saying that my top chamber is fine and is sending the signals down to the bottom at a normal rate, the issue is that the bottom Chambers don't receive that signal. Therefore now I have my pacemaker, once the top sends the signal down the bottom paces. And my pacemaker is set to 40 bpm so that's the lowest my rate can be. However shouldn't my heart rate just be whatever my natural rate is now, almost like someone's with a normal heart? I've noticed it still goes quite low, 48 and 49 sometimes but it picks up nicely. Is that just because I have a naturally low heart rate or do my settings need tweaking? They did say something about a large delay which they'll assess for now and look at in my first consultation.

Thanks again!

 

Tom


10 Comments

Hard to tell by what you've said so far

by AgentX86 - 2019-11-29 20:16:31

It sounds like you have a heart block and bradycardia/SSS (Sick Sinus Syndrome).  Since your pacemaker is set to DDD mode (Dual pacing, dual Sensing, Dual action). 

- Dual pacing indicates that  the Right Atrium and Ventricals (in your case, both ventricals, since you have your ventricular lead in the bundle of His) are paced.

- Dual sensing indicates that both the RA and ventricals are sensed.  If either doesn't pulse at the right time, the pacemaker supplies the pulse to either the right atrium, ventricals, or both - at the right time.  If they work properly, the PM sits and watches until it's needed again.

- Dual mode indicates that the pacemaker can either "Inhibit" if a pulse is sensed, "Trigger" a pulse (I don't fully understand this mode), or nothing.

Atrial pacing:

- If the RA doesn't fire the PM "senses" (second 'D') that the SI node isn't doing its job and it supplies the pulse after some preset time (60/40 seconds, in your case).  If your atrium does fire within that time will "Inhibit" the pulse (the second 'D'). 

Ventricular pacing:

- If your RA does fire (or not, since the first character is a 'D'), and after some time it looks for the pulse, passed through the AV node, into the ventrical.If the pulse is sensed (again, the second 'D') it "Inhibits" pulsing the ventricals. 

- If it doesn't sense the ventricular pulse, it supplies it. 

That's the short course.  For more information see:

<https://derangedphysiology.com/main/required-reading/cardiothoracic-intensive-care/Chapter%209.1.2.7/single-and-dual-chamber-pacing-modes>

So, yes, from what you've said, I think there is some tuning to do.  Your EP probably wants things set up pretty conservatively until your heart gets used to pacing and he can see how you're performing.  You really need to give him all the feedback you can (what you can do, what you want to do, and how you're feeling - energy/sleep/attitude).

I Dont have SSS

by Tommy1996 - 2019-11-30 05:51:10

Hi Agent thanks for the information that clears up the settings side of it. I don't have SSS, before I had my pacemaker they weren't worried about my heart rate increasing, on exertion my heart would slip back into first degree block so the complete block was intermittent. I think you're right that some tuning is probably necessary, all questions for the EP.

delay

by Tracey_E - 2019-11-30 11:16:19

I'm no expert but I'll bet that decreasing the delay brings your rate up. It's great that they start off letting the heart do as much of the work as possible so we pace as little as possible, but sometimes we need the pacer more than that. Your starting settings were a good guess to see where you are. They'll reassess at your next appointment. If you are feeling dizzy, ask to be seen sooner, but it sounds pretty normal to me. It's also entirely possible you've got a little SSS going on that the block was masking, which is also an easy fix with settings. 

Welcome

by Graham M - 2019-11-30 17:07:50

Hi Tom,

Welcome to the woderful world of pacing.  I'm sure this will change your lifr for the better.

I'm not very experienced as I amonly just over 3 months out, but can share what I have learned in the last 3 months,

I have a Mobitz Type 2 block which is one step before a complete heart block, but is treated with a DDD pacemaker the same as yours.

In Type 2 block, the sino-atrial (SA) node in the right atrium works as normal, but not all signals get through to the ventricles so my heart skips beats.  In Complete Heart block, no signals get through to the ventricles, so the heart relies on so called "escape" beats to keep the ventricles going.  Thus, the atria beat as normal but instead of the atria and ventricles beating synchronously, the atrial beats are regular whilst the ventricular beats are random.  

In a DDD pacemaker, both leads are able to sense and pace.  When a normal atrial beat is initiated by the SA node, the pacemaker will sense this and if a ventricular beat is not initiated within a given time interval (mine is set to 150ms), a paced ventricular beat will be initiated.  If a normal ventricular beat follows the atrial beat, then the pacemaker will not do anything. The result is that an atrial beat will be immediately followed by a ventricular beat in the same way a normal heart would beat.  It is as simple as that.  In your case, the majority, if not all ventricular beats will be paced. HIS pacing is the most efficient form of pacing as it paces all the bundle branches simulateously. 

You say that you have a naturally low heart beat, but this will be partly due to your CCHB.  Your lower pacemaker setting will be at a rate that the physiologists think will be best for you, but it is often a matter of trial and error to get it right.  Mine was initially set at 60 bpm, but reduced to 55 at my first checkup.

You are only a couple of days out and are probably feeling a bit rough at the moment, but in a couple of weeks when things have healed up a bit, I'm sure you will feel a lot better.  Don't worry too much about your heart rate - it will go up and down for a while until your body adjusts and it settles down.

My advice to you is to hit the internet and learn as much as you can about CCHB.  There is some rubbish out there, but also a lot of useful and important information.  

Good luck and best wishes,

Graham.

simpler answer

by dwelch - 2019-12-01 00:57:21

Hopefully I can make a simpler answer, the above long answers are great by the way but may take some studying.

Your problem sounds like a block, as you described the electrical connection that synchronizes the upper chambers and lower chambers is blocked.  Broken.  You can choose to thank evolution or religion as to why you/me/others with a heart block are alive, the lower chambers beat to their own rythm and we stayed alive this long because of that.  It is innefficient and eventually dangerous as the heart muscles thicken and the heart gets big and then bad things can happen.

The pacemaker primarily listens to what the upper chambers are doing and makes the lower chambers follow along.  This does not mean that your overall body generated rate will change with a pacemaker, it means that the heart doesnt have to work as hard fighting itself.  Ideally your body still drives the overall rate the pacemaker in this case is simply repairing the heart block.  You still get to run the gas pedal in your car, the pacemaker has fixed the gears in the transmission so car reacts properly to your input.

SINCE you have a pacemaker and in part how they work perhaps, the devices have an upper and lower limit, so if your body wants to go faster or slower then the pacemaker drives the whole heart not just the lower half to keep you within those limits.  if you go too slow or too fast then the pacemaker does take over the gas pedal in your car, until you get it within that range.

My resting rate was in the 40s before my first one but my lower limit was set higher so I was probably paced on both ends until I got older and less in shape.

I would argue the pacemaker helps your heart to run at a lower rate now, the heart is much more efficent, like a normal heart, it is no longer fighting itself, so it doesnt have to work harder, one would expect it could now do the same job it used to do before at a lower rate.  Just a thought no basis in fact.

If you were at a resting rate in the 40s before, and they were nice enough to set your lower limit to 40 and your resting rate is still in the 40s then great, you dont have to learn to sleep again at a forced higher heart rate like many of us with a heart block and a pacemaker.  I am not hearing anything to worry about yet.

And before you ask 100% paced for heart block is also nothing to worry about, doesnt mean you are 100% dependent it just means that you have a block and the pacer is fixing the timing of the lower chambers.  Every beat every day as needed, thats pretty much what you want it to do, so thats normal and expected.  When you go in for checkups they will turn this off for a few seconds and see if your body takes over again, meaning if the pacer werent there you would still have your religion/evolution taking care of you.  Not 100% dependent just the pacer fixes the block.  The worse the block the higher that percentage is.  Complete, level 3, heart block expect a high percentage, perfectly normal.

100% on the ventricles does not mean your battery runs out sooner, instead it means you start off with a bigger battery so the device can last about the same amount of time as someone with some other problem that isnt paced as much.

Okay I made this too long, but hopefully simpler.  What you have described is perfectly normal and expected.

 

 

HR

by MrTech - 2019-12-01 13:00:58

 

A resting heart heart rate (especially the odd notice here are there) does not imply SSS. 

It may be ones own natural rate at rest. The atrial ( top chamber )  histogram will  show the heart trend since your last check. This is useful in determining any issues with ones natural heart rate and how it changes with activity. 

Someone with Complete heart block any type of block ( this refers to electrical block btw, nothing to do with blocked arteries) means the junction box (Av node or HIS below AV node)  doesn’t work it at all is working well. Level of block determines this. 

Heart Rate

by AgentX86 - 2019-12-01 20:55:03

What you say is true, sorta, but a resting heart rate (this is after the pacemaker was implanted - so has nothing to do with the heart block) was less than 50, so by definition Bradycardia.  Unless he's an olympic athlete, there may indeed be some SSS that's just now being uncovered.

I'd talk with my EP about this.  It's easily found in the PM interrogation reports and easily fixed with pacemaker settings but 48bpm *is* Bradycardia.  There certainly is no emergency here.  The PM isn't going to let it go below 40 (but that may be too low).

 

 

My thoughts exactly!

by Tommy1996 - 2019-12-03 17:17:03

This is what I've been trying to ask to be honest. Some days my resting is normal like 65bpm and sometimes it sinks to like 46bpm. Sometimes when I run up the stairs and move about a bit it goes up nicely to 70 or even 80 and sometimes it just sits at 60. I've been just putting it down to what I'd eaten that day/how much I'd slept and my body is adjusting to the PM. My heart rate sits at the minimum (40) as soon as I lay down for bed and stays there until I get up in the morning every night. 

But yes now the PM acts as a conduction system in the HIS, if there are no other issues I should have a relatively normal HR which as you say if im not an athlete (which im not) should be higher than 45ish. 

Is this something I should call my consultant about sooner rather than later or can it wait until my first appointment in 3 and a bit weeks? 

Histograms

by MrTech - 2019-12-04 12:35:58

Look at the histograms (atrial ) when you are next in and look at the general spread to see if there is a blunted response (the professional checking your device should do this anyway and be able to evaluate this and act accordingly). 

 

 

 

 

Excellent thanks!

by Tommy1996 - 2019-12-04 17:33:41

I will make sure to ask for this during my consultation cheers.

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