Heart Cells & Arrhythmia

[reezlemom]

My rough understanding of the heart's function is that it has more cells than it needs, thus if damage does occur and some cells die, the heart can still regain full function because the other cells are them called upon. Is that correct?

I was discussing this with a few women who have experienced atrial arrhythmias following the birth of a child. While I was the only one who had PPCM of the many who have the PAC/PSVT/a-fib complaint following childbirth, it still got me to wondering.

I was curious if the changes in the working cells in the heart can bring something like this about, and also if you had any insight on what cardiac changes in pregnancy might trigger the onset (or worsening) of atrial arrhythmias? I thought it was quite fascinating.

An ER doctor once told me that it's not uncommon for women to develop supraventricular arrythmias after having children, but he couldn't explain why, saying, "They just do." :rolleyes:

[JAMESFETT]

That's right--fortunately the heart, like many organs, has quite a large reserve in functioning cells, and loss of some may not inflict loss of function because the reserve picks up for that loss.

It appears that the inflammatory process in the heart in PPCM is very spotty, and symptoms depend upon where the inflammation is located. If extensive in the left ventricle, there will be an impact with decrease LV EF. If the inflammation is in the primary electrical network of the heart, over on the right side and in the septum between the two ventricles, there may be more rhythm problems. Of course inflammation in the left ventricle can also be irritative and cause PVCs, even ventricular tachycardia/fibrillation.

JD

[JAMESFETT]

P.S. It is not totally clear yet about the role of beta-1-adrenoreceptor autoantibodies (that are common in PPCM and IDCM), but they are "agonistic," meaning that they put the heart into overdrive, and thus may also cause rhythm problems. This is one way that beta-blockers are beneficial since they counteract these overactive adrenoreceptors. Those antibodies form as a result of heart muscle cells being damaged and releasing the cardiac proteins that are then exposed to the immune system which can no longer distinguish between "self" and "non-self." I haven't seen any studies indicating that this mechanism is at work in normal pregnancy nor am I aware of studies showing increased arrhythmias as a consequence of pregnancy apart from pregnancy-associated cardiomyopathy.

JD

[reezlemom]

Very cool! I've always found the heart to be a fascinating organ, but never so much as since I learned all that I have here. I also had no idea beta blockers did so much. I'm so thankful for the research, technology and treatments we have available to us.

Sorry, I'm a total science nerd, I love this stuff :o Thanks for the reply!

[JAMESFETT]

Involvement pretty much uniquely of the right ventricle and electrical system of the heart (SA node, AV node, bundles) by a cardiomyopathy may be most characterized by cardiac rhythm abnormalties, as in arrhythmogenic right ventricular cardiomypathy (ARVC).

JD

[reezlemom]

So depending on what portions of the heart the cardiomyopathy involves, arrhythmia may or may not be an issue. Interesting. Do these arrhythmias tend to persist beyond healing (I would guess it's possible just from changes in the cells) or would this typically pass with recovery?

I figure my PPCM buggered with my already irritable electrical system, so I just stay thankful for recovery and roll my eyes at the rest - a minor annoyance considering some alternatives. It's kind of fascinating. On the one hand, the heart is extremely resilient after an insult. On the other, it can be quite peevish electrically. :rolleyes:

[JAMESFETT]

Yes, for some types of arrhythmias that would be true. However, ventricular irritability may be associated with involvement anywhere in the ventricles, and would be manifest as PVC's, VT, and VF.

JD