Atrial Fibrosis..

Hi, Could anyone give me anymore information about Atrial Fibrosis please as I haven't heard of this before....C

Pathophysiology

Atrial fibrillation is thought to be caused by atrial fibrosis, and lost of atrial muscle mass. This fibrosis would occur as result of aging, chamber dilatation, inflammatory processes, and genetic causes. Dilatation of the atria can be due to any structural abnormalities of the heart that cause a rise in the intra-cardiac pressures. This includes valvular heart disease (such as mitral stenosis, mitral and tricuspid regurgitation), hypertension, and congestive heart failure. Inflammatory processes such as sarcoidosis, and other autoimmune disorders will also result in similar cardiac remodeling. Finally, mutation of the lamin AC gene has also been associated with fibrosis of the atria and seen in familial cases.

Dilatation of the atria activates several molecular pathways, including the renin-aldosterone-angiotensin system (RAAS). Angiotensin II is upregulated in response to stretch leading to increase in matrix metaloproteinases and disintegrin, which leads to atrial remodeling and fibrosis, with loss of atrial muscle mass. The use of an angiotensin-converting enzyme inhibitor (ACE inhibitor) is then an effective mean to lower atrial pressure, and wall stress. Fibrosis is not limited to the muscle mass of the atria, and may occur in the sinoatrial node (SA) node and atrioventricular node (AV node), often leading to sick sinus syndrome (SSS). Prolonged episodes of atrial fibrillation have been shown to correlate with prolongation of the sinus node recovery time, suggesting that dysfunction of the SA node is progressive with prolonged episodes of atrial fibrillation. Both arrhythmias are commonly seen together. Atrial remodeling, change in electrical refractoriness, and disturb contractile function make cardioversion unlikely to succeed.

In atrial fibrillation, the regular impulses produced by the sinus node to provide rhythmic contraction of the heart are overwhelmed by the rapid randomly generated electrical discharges produced by larger areas of triggering atrial tissue. Those focuses are often localized to the pulmonary veins involving re-entrant conduction pathway. Ablation of the triggering focuses becomes an interesting management option to restore sinus rhythm (Picture 1).

Atrial fibrillation is different than flutter in which there is the presence of a more organized electrical circuit. The activation is usually within the right atrium and produces characteristic saw-toothed p-waves on the electrocardiogram (ECG) (Picture 2).

Picture 1. Atrial Fibrillation

[jennydog]

There was a link several days ago on a post about mineral supplements and it mentioned atrial fibrosis. When I googled it I found "atrial fibrillation - Pathophysiology" This is a teaching aid from Toronto University.

I had my ablation 19days ago. I was told that I had an enlarged left atria with scarring. One pulmonary vein was so scarred that it didn't need ablating and I have odd plumbing to the heart. I have to assume that this scarring is fibrosis. Was I born with it or has something caused it? We do know that there is a genetic link but beyond that there will never be any proof as to the cause of my AF.

I found this teaching aid most interesting and readable.

AND an update, 19 days and I still haven't felt my heart.

[BobD Volunteer]

Carol you think too much. Nobody really knows what people get AF yet. Just accept that you have and are going not to have soon. I can say this as I know you I think.

Bob

[Hidden in reply to BobD]

Bob,

If you know me as well as you think you do you will know that I have a tremendous thirst for knowledge.As knowledge is power when we are talking AF as you keep telling us...

Looking forward to seeing you soon...

Carolx

[BobD Volunteer]

O K its a fair cop! A bit naughty of me really. I do see so many articles supposedly about all the latest developments and found much of it just muddies the water. Call me small minded but I only ever accept what AFA publish as I know it has been vetted by the very best people around.

Must book the table for dinner soon so will be asking for a show of hands to check numbers. I think it may be over ten this year.

See you soon.

Bob

[BobD Volunteer]

They should be one and the same Concerned. The problem with us lay people looking at some of these medical documents is that the language used is often beyond our understanding and can and often does increase natural worry about the condition. For example the second para above is saying in a very complicated way what I have often talked about for example with athletes and fighter pilots. e g " it is thought that the work done by the heart causes the left atria to enlarge stretching the pathways and allowing extra rogue ones to form. " Which seems the most scary to the lay person.? As I always say knowledge is power but we have to be careful that we absorb only what we understand and without proper guidance that understanding may not be correct. .

In a multi national forum such as this we also have to be careful about reading accounts of new procedures as what may be available on the North American continent may not be in Europe or Australia for instance. It is for this reason that I recommend only AF Association approved fact sheets.