ventricular rhythmus

pacing with av block and afib

by Tracey_E - 2020-12-08 08:57:25

With av block (no afib), the sinus node works normally and the pacemaker works by pacing the ventricles every time the atria beats. 

Your lower limit is 60 so any time the sinus rhythm (atrias) gets under 60, it will pace the atria also to make it faster. If your pulse is 70+, then that is your own sinus rate, not the atrial lead of the pacemaker. The ventricles would still be paced, with av block they almost never beat on their own.

Ventricular escape rhythm is what the ventricles would do if not paced, when they are beating independently of the atria. 

Afib means the atria is quivering, not fully beating, which usually means a high heart rate. Some pacers can pace us out of afib but I'll let someone else explain that! I do not fully understand how it works.

Your English is excellent! Better than many native speakers ;o)

Atrial Fibrillation (AFib)

by Gemita - 2020-12-08 12:34:52

Dear Dorothea,

Welcome.  We have family in Cologne - I see you live there!   Tracey has answered your question on pacing with AV block but I thought I would just say a bit about AFib, if that would help?  I expect you already know it is a choatic rhythm disturbance which can be difficult to treat.

The natural course of Atrial Fibrillation (Afib) is to progress if it is not firmly controlled and I can see your Afib has progressed and that it was occurring as frequently as 98% of the time last November.  May I ask whether your doctors have ever tried to control it through medication, cardioversion or an ablation?  Do you have any symptoms from Afib?  Some patients are unaware of being in Afib and therefore have few symptoms, others are not so lucky.  I feel every pausing, speeding, slowing, fibrillating beat and know immediately when it starts and when it stops.  

I have Afib with a rapid ventricular response rate which means that the atrial rate can surge well above 300 bpm, so my doctor has set up a programme in my pacemaker to stop these dangerously high heart rates from passing through my AV node and driving up my ventricles. 

The programme (feature) is called Mode Switch which is triggered when my pacemaker detects an atrial tachyarrhythmia.  This switches pacing from the programmed atrial tracking mode to a non-atrial tracking mode (mine goes from AAIR to DDIR) and remains in this mode until the atrial tachyarrhythmia ceases. Then my pacemaker switches back to the atrial tracking mode. The switching occurs whenever it detects an atrial tachyarrhythmia above a certain rate (say 130 bpm and above).  The downside of this clever feature is that with my frequent in and out episodes of AFib, it can happen multiple times a day and at night and I really feel these switches.

I do not know what is set up in your pacemaker;  perhaps you have the same programme as well as other programmes to help control your Afib?   Do you know how fast your heart rate goes during an Afib episode?  I suspect even with Grade 3 block you may still intermittently be getting some occasional signals passing through the AV node driving up your ventricular rate, although your rate of 70-73 bpm is a normal heart rate.  Afib can be a slow, normal or fast speed irregular arrhythmia or a combination of all three in one episode  which is why it is called "irregularly irregular".  

When I first got my dual chamber pacemaker my doctor said that in some patients, pacing at a higher minimum steady rate of say 70 bpm or above, may help to control Afib.  I remember he explained in some detail that for some patients, there is clear evidence to show that falling heart rates may be a strong trigger for their rhythm disturbances and that a higher, steadier heart rate might help outpace an arrhythmia like Afib.  A pacemaker doesn't work for everyone, but it helps me.  I still get some really nasty Afib episodes but generally now their duration and frequency is lessened.  My symptoms therefore are better controlled and my quality of life much improved.

Afib and pacemakers

by AgentX86 - 2020-12-08 21:04:19

Your Elnglish if fine.  Welcome to the club.

Afib, by itself, isn't dangerous.  The big danger is in blood clotting it the inefficient atria and moving to the lungs (pulmonary embolism, or even worse, to the brain, ischemic stroke). This is effectively treated with anticoagulants ("blood thinners"). 

The other problem, much less dangerous and not an immediate danger is cardiomyopathy (enlargement of the heart) caused by a high heart rate.  Keep the heart rate under 100. (with drugs, most often beta blockers) and this problem goes away.

Some have other issues caused by Afib but the above are the dangers for 90+% of us.  The remaining problems are more quality of life rather than length of life.  Those who are asymptomatic are better off just treating the above and "have a nice day".  Symptoms, for those who do have them, range from mild inconvenience, to major inerruptions to their life, to even debilitating restrictions on what they can do. 

Afib is a progressive heart disease.  The common phrase is  "Afib begets Afib".  Treat it when t appears or it gets increasingly more difficult or  perhaps imposible later.  Since you're at a  98% burden rate...

Pacemakers rarely help because atrial pacing doesn't keep the abnormal electrical pathways from transmitting the electrical signals from the pacemaker any less than from the sinus node.  The AV node is intact, so these signals get transmitted to the ventricles normally, where the pulse is felt/measured. In the case of heart block, the same happens with the exception that it's the pacemaker, itself, transmitting the Afib signal to the ventricles.  In my case, they intentionally gave me heart block (AV ablation) and pace me in the ventricles only so whatever the atria are doing (nothing useful) is irrelevant.

Your situation is the same as the second case, above, I think.  I highly doubt that you have an escape rhythm that high.  Any escape rhythm from the ventricles is often in the 20s or maybe even 50s, but may be even lower (or nonexistant).   I've never heard of an ventricular excape rhythm in the 70s.  You may be getting PVCs, which are related but not regular. An excape rhythm from the AV node (often called a juncional rhythm) can be in the 30s to 40s but your AV node is not functional.

AgentX86 is absolutely right to focus on dangers of AFib

by Gemita - 2020-12-09 03:28:41

Dorothea, as you will probably know, the two most essential treatments for Afib are of course anticoagulation if you have risk factors for an AF related stroke and control of heart rate to protect from worsening symptoms from a continuously high heart rate, which could lead to heart failure over time if rate is not firmly controlled.  I am taking a beta blocker (Bisoprolol) to control my heart rate and anticoagulant (Edoxaban) for stroke protection.

Hopefully you are well protected?  I hope all goes well for you 

a-fibs and pacemaker

by dorothea - 2020-12-11 05:09:36

hello, I feel embarrassed because of the detailed comments you all posted. much work! thanks a lot!  I will give you a summary of my cardiac problems for a better understanding.

2010 I had my first a-fib. I went to a cardiologist in Cologne . He found  a mitralvalve iinsufficiency  grade 2, due to a prolaps of the anterior leaflet. I started  a therapy with b-blocker and anticoagulation - Xarelto.  After a year I had severe bladder bleeding, I switched to Eliquis., no problems ever since. 2016 they found a deteriotation of the mitral valve insufficiency, grade 3. . I had two options: a minimal-invasive mitral valve reconstruction or a controlling of my physical condition every3 months. I choosed the operation. The cardiosurgeon promised to do  an ablation at the end of the operation, called pulmonal venous isolation. Unfortunately he could not do the ablation, as the heart-lung machine did not allow a prolongation (the use of HLM is limited). The repair of the valve was successful. Nearly two years later I had a total heart block in the middle of the night  (A-V- block grade 3). I had a 5% chance to survive.  Thanks to a very good emergency doctor I survived, she had a strong feeling, that I was suffering from A-V block. she started external pacing and brought me to the hospital.  She was right, they implanted a dual chamber pacemaker. As I mentioned before, a-fib's occurred quickly. I did not feel them.. My implantation pass had a warning:  AT/AF burden exceeded. Therapy with Eliquis and metoprolol was continued.. One year later my cardiologist said, that the wire/electrode for the atrium was useless. I did not need a two chamber pm. The wire for the ventricle would have been enough. Having a PM I thought  nothing bad will happen again. But that's not true.  Within 6 weeks I noticed ventricular arhythmia, which resulted in left and right heart failure. Ultrasound examination showed all four valves were fully open, no closure at all. Doctors said, maybe the a-fib's  jumbed to the walls and septum of the ventricles.  They added to my medication digitoxin tablets, within 10 days my heart recovered. 

As I wrote before, I am worried about the high percentage of the a-fib's (98%) and I wonder about my regular HR (70-71 bpm). I would have asked my cardiologist, but we have to deal with covid-19.  Doctor and patient are very close during the examination. Wearing a mask does not exclude completely a transmission, so to protect the doctor we should not discuss things  with him.

My questions, particularly my regular HR, are not essential, more or less curiosity.

thanks for reading, dorothea

(by the way I am dutch, living in germany since 1970)

showed

AFIB and CRT therapy

by Gemita - 2020-12-11 15:27:55

Dear Dorothea,

Thank you so much for taking the time to write in such detail.  Please do not feel embarrassed about our long posts.  We want to help you but electrical problems of the heart are so complicated to write about and it is difficult to keep our posts short!  I hope we have answered some of your questions, although I am not so sure that we have satisfied your curiosity. 

You have quite a history.  I am glad you are on Eliquis instead of Xarelto because I believe Eliquis is a safer anticoagulant for those prone to having a bleed, especially a gastric bleed.

I am assuming that you are mainly ventricular paced now because your AFib has become so persistent and that is why your doctors say you do not need an atrial lead, but I would still want to keep the atrial lead and to try to control the Afib.  I can see you were not able to have a pulmonary vein isolation ablation (PVI ablation) because of difficulties at the time.  Would your doctors still consider doing a PVI ablation to try to stop your Afib or are they saying it is too late? 

I was concerned to read your statement “having a PM, I thought nothing bad will happen again. But that's not true”.  That is very sad Dorothea because a pacemaker, if it is well programmed and the settings have been set correctly for you should make you feel better, not worse.  I can only assume it has been the Afib that has caused so many problems, forcing pacing to occur in the right ventricle, and with high right ventricular pacing, your two ventricles have become poorly synchronised (coordinated), causing heart failure.  A CRT pacemaker may help if the treatment you are on (Digoxin and Metoprolol) fail to improve your heart failure.

Can you phone the cardiologist or write to the cardiologist and ask him/her some questions?  You could ask about CRT therapy and whether anything can be done to try to stop your Afib?  Your regular HR of 70-71 bpm is perfectly normal because although your minimum pacemaker set heart rate may be 60 bpm, your own “unpaced” heart rate may often be higher than 60 bpm.  Does that make sense Dorothea?

pacemaker and catheter ablaton

by dorothea - 2020-12-16 08:48:43

hello  Gemita, thanks a lot for your comment. 

At the time I had 65% A-Fib's  ( maybe a year ago) I asked my cardiologist, if a catheter ablation was possible in spite of the pacemaker. I knew that the cologne Heartcenter (their cardiac surgery did 2016 my mitralvalve reconstruction) , cardiology department did these catheterablation in patients with a pacemaker. . He said, that he would not recommend it, as I don't feel these fibrillations. but he did not explain , why not.  he could have mentioned a medical paper about possible negative interactions between the wires and the catheters. I would have understood him. Now I found  a paper in Pubmed.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252655/

Indeed, the procedure would be quite risky. 

my next appoitment is may2021  . I will ask him, where the trigger for the Atriumfib. could be, stiil in the pulmonal veins?   Obviously not, as I was told after the implantation , that about 40% of the people have A-fib's, even the people who had never before fibrillations.

maybe we will be vaccinated by then , and I can focus my attention to my problems. 

In germany we are used to say at the end of a letter/mail:  stay healthy!!

dorothea