Dick - Atrial Fibrillation

A-fibrillation Dick9

= SVT w disorganized activation/contraction of atrium; w irreg irreg rhythm bc of rapid irregular stim to AV nd fr the atrium w variable conduction...

-ventric response d/o ability of AV nd to transmit, which depends on its EP props along with the autonomic state...

Epi

-#1 rhythm d/o in ppl overall- 0.4% of gen population will get it; 6%of ppl >80yo get it

-Extremely rare in peds population

Assoc Dz

-more common in pt w CHF, MS, MR, htn, hyperthyroid, WPW

-a-fib + WPW- life threatening bc no decremental conduction at the AP so can --> v-fib

-also incr risk w AVNRT, AVRT, AET, a-flutter

-ablation of each of these does decr the a-fib

Mech

-? for certain

-multiple wavelet theory- multiple rentrant waves are continuously circulating thru the atrium, use migrating central cores of refract tissue to rotate around...

-single circuit reentry- a single mother rotor serves as a hub w many accessory circuits coming from it

-multilpe circuit reentry- rapidly discharging ectopic focus w fibrillation; in favor of late bc of excitatory loci seen in P Vns, and good response to their ablation

-sustained a-fib --> substrate more conducive to support sustained a-fib via remodeling, w incr fibrosis, change in gap jct/ion channel experssion...

Tx

-hard to beat!

-rate ctrl (inhib AV nd conduction) vs rhythm ctrl (restore SA nd rhythm) - ?which is better

-Cox-Maze procedure- create many incisions and then repair them to attempt to channel the signal bn the sinus nd and AV nd w minimizing formation of reentrant loop

-good success rate, but much surgical morbidity

-EP equivalent of Maze doesnt work well as of yet, but ablating PVns to isolate them electrically is having success... better than rate or rhythm ctrl via Rx

-Pacemakers/ICDs- used to Tx and prevent a-fib onset, but not shown to be better than Rx