Intermittent AV block, what actually is it?

A good read

by Lavender - 2023-07-24 13:55:18

This article explains a lot in easy to understand terms. Copy and paste:

https://www.ncbi.nlm.nih.gov/books/NBK459147/
 

I do think my vibration sensation which is felt early as I arise, or when at complete rest is somehow part of my vagal system. I do get lots of vagus nerve sensations at times particularly when at rest. 

At times lying on my left side causes this sensation of vibration or electrical current through the upper body and arms  

Having some pacemaker adjustment has lessened the intensity and frequency of me noticing it.  It no longer frightens me. 

I am a fan of deep breathing to settle and calm myself. I do the 4-7-8 method of a slow four count drawing in air through the nose. I hold to a count of 7. I exhale slowly as if through a straw to a count of 8. Just doing even four breaths like that relaxs me. 

Thank you Lavender

by John_Locke - 2023-07-24 14:13:23

That was a great overview of AV blocks, more in depth than just reading Wikipedia but still accessible, thank you.

What I'm really trying to understand though is not the general mechanism of an intermittent AV block. Throughout most of the day, my heart functions perfectly fine without pacemaker assistance, but every day I have a few episodes of an AV block as described, sometimes with individual skipped beats, sometimes multiple.

What is it that might change in my body, mechanically, electrically, or chemically, to cause this when it happens?

leads

by Tracey_E - 2023-07-24 14:46:18

If symptoms are positional, have them check and make sure a lead hasn't shifted. 

Do you know why your family members have pacers? AV block would never require an ablation, that's usually associated with afib. There are other pacers in my family, also, but none for av block. 

Mine, like many others, is unknown cause. There is a genetic link, mothers with Lupus are more likely to have babies with av block. It can be associated with other auto-immune diseases. It can be caused by some surgeries and medications, sometimes infection or diseases like Lyme. But many of us have otherwise structurally normal hearts and no known cause. 

Triggers

by Lavender - 2023-07-24 14:58:46

John...there are many causes as Tracey said. I asked my EP group. They told me mine was fibrous, aging degenerative, progressive conduction disease. It may have been inherited. They really don't know. 
 

My brother had structural heart damage as well as electrical conductivity issues. Being an alcoholic hastened his death at age 60. My heart is structurally fine. No meds or surgery needed. My electricity flickers. 
 

I know you would like to know the trigger and somehow be more in control. You might never know. It is called intermittent for a reason 😉My cardiologist said sometimes people's block is tricky to even diagnose. Mine is a sneaky ventricular standstill arrhythmia. I'm blessed that it was caught on a heart monitor. That bought me a CRT-P. 
 

From Cedars-Sinai:

For most people, heart block develops as you get older. It happens as the wires (nerve fibers) that connect the top and bottom of the heart develop fibrosis and eventually fail. Sometimes this may happen because of advancing age. Any process that can damage these heart wires can result in heart block. Coronary artery disease with and without a heart attack is one of the most common causes of heart block. Diseases that weaken the heart muscle (cardiomyopathies) can also damage the wire. Heart block can also be caused by any disease that can affect the heart such as sarcoidosis and certain cancers, or any disease that results in heart inflammation. This can be an autoimmune disease or infections. Electrolyte problems such as high potassium levels can also result in heart block. Additionally, some heart surgeries can damage the conduction pathway leading to heart block.

This made some sense

by John_Locke - 2023-07-24 14:59:02

In case it's relevant to anyone else, what I have appears to be refered to specifically as paroxysmal AB block. This article goes into the mechanisms for what can set these off: https://onlinelibrary.wiley.com/doi/full/10.1002/joa3.12245

I need more time to fully digest this but in short they classify it into one of three groups:

- Vagally mediated, where the AV node is able to conduct normally but a high vagal tone supresses it. In this case, missing activity from the ventricle is always associated with a slow sinus rythm. This is the "break too hard" case.
- Intrinsic, where part of the conductive tissue is left in a bad electical state after something like a PVC hits it at the wrong time. Only another event like a PVC can then reset the system and restart a normal beat
- Idiopathic, being doctor speak for "something else"

It now makes more sense to me what my EP meant when he talked about "dropped P waves" during exercise as being the deciding factor. I do get skipped beats at night in line with the description of vagally mediated block, but apparently (though I've never felt this) also when raising the heart rate during exercise, indicating an intrinsic block.

Family history

by John_Locke - 2023-07-24 15:04:38

It seems that my dad's family is generally cursed when it comes to heart health, though to be fair, some of them have had other clear risk factors (seditary lifestyle and a fondness for food).

In the mix from what I've been able to gather is bradycardia without other heart conditions, pacemaker following heart attacks, stoke, and various flavours of afib treated with medication. I don't know the details of what lead to the ablation and understand that it would not be for a heart block, it's just unfortunately a long list of heart related conditions when you start listing them all out like this.

causes

by Tracey_E - 2023-07-24 17:14:23

Electrical problems are usually different in cause from plumbing problems. Poor lifestyle choices cause plumbing problems- clogged arteries and heart attacks. Nothing we did caused an electrical problem, nothing we could have done differently would have prevented it. Some are genetic, many are not. 

Causes

by AgentX86 - 2023-07-25 16:16:10

In both cases, it's a matter of choosing your parents poorly.  A poor diet doesn't help anything but even structural problems have a strong (perhaps not understood) genetic component. It's better to swim in a clean pool.

Like diet and structural problems, life choices can cause electrical problems, though at the other end of the spectrum.  Endurance athletes have a very high incidence of electrical issues, primarily Afib.  It's thought that the larger and more muscular heart, necessary for the sports, causes fibrosis and thus electrical problems.

Damned if you do, damned if you don't.