= 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