uncontrolled atrial fibrillation

[zzyzx]

I'm trying to understand the pathophysiology behind uncontrolled AF with a very fast rate (over 160). I understand that for other SVT's, the cause is either an accessory condution pathway (as in WPW) or a re-entry mechanism in the area of the AV node. So how is it that you get AF with very fast rates? Is the AV node defective in not being able to block all these impulses, or is there also some sort of re-entry mechanism going on?

[chbare]

Zzyzx, you are correct. The AV node cannot block all of the multiple chaotic impulses from the atria and you develop a rapid ventricular response. This is why some people call this atrial fibrillation with rapid ventricular response. In other disorder such as, WPW and LGL, you have an accessory pathway that bypasses the AV node.

Take care,

chbare.