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Unifying Theory of Atrial Fibrillation

October 16, 2016

“Rotors are just a way of thinking about and visualising reentry. There is nothing magical or unusual about rotors…the concept of a rotor is just a biophysically more realistic concept of what maintains reentry; you can get multiple circuit reentry in a pure rotor based model.

First of all, if you take a pure mathematical model of the atrium that ‘s highly realistic and induce reentry, which you can do easily, it’s a rotor. It’s not a leading circle in terms of what it looks like and what determines it. It’s a rotor.

If you have something that stabilises the rotor such as a large refractory gradient -which we can reproduce mathematically with acetylcholine distribution or probably what happens with vagal AF – you get stabilisation of a rotor and you can get AF with a single rotor maintaining it.

If you have an anchoring factor, like fibrosis presumably, or something like that, you can get a much more stable rotor. If you don’t have any of those things you need a very big substrate, and when you have a very big substrate then you can reach a situation where you don’t have stable rotors but the rate of rotor production and destruction (balances) –  when a rotor hits a barrier you get two daughters counter rotating rotors which annihilate each other; if the substrate is large enough the rate of daughter rotor formation and daughter rotor annihalation becomes sufficiently equal that you constantly maintain  enough rotors to maintain AF even though none of them are longstanding.

That’s all conceptual.

How that relates to patients with long standing AF or long standing persistent AF I think is that you have factors that anchor the AF in terms of local fibrosis, maybe anatomical features, less likely functional properties, and so you have some degree of stability of rotors and some combination of rotor production and rotor degradation.

The real question, and frankly speaking the disagreement between Sanjiv and Michel and Pierre as i see it, is how stable those rotors how are whether they really are relatively stable enough in space that they last for a long time and you can eliminate them or whether they are less stable but they stay in a relatively constant region.

I think in the end the differences between them are not really so large. It’s just a question of whether you see a single rotor in a region remaining absolutely stable over time, or a region as much more likely to harbor rotors and therefore more rotors sit there. In the end the two ideas may actually converge and come down to the same thing.

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From Stan Nattel, discussing rotors and AF at HRS in ?2015.

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