Pulmonary vein encircling ablation alters the atrial electrophysiologic response to autonomic stimulation.
OBJECTIVE
Pulmonary vein encircling ablation is often effective in the treatment of atrial fibrillation (AF). The success of the procedure does not depend upon creation of continuous lines of block. Thus mechanisms by which pulmonary vein encircling can cure AF remain unclear. Stimulation of cardiac autonomic ganglia alters atrial refractoriness and potentiates AF. We hypothesized that pulmonary vein encircling alters atrial autonomic function and that these alterations account in part for prevention of AF recurrences following ablation.


METHODS
Atrial effective refractory periods (ERP) and AF inducibility were quantified in ten dogs before and during central autonomic nerve stimulation. Pulmonary vein encircling ablation was then performed and electrophysiologic testing repeated. In two dogs subjected to sham procedures measurements were repeated without performance of ablation. Hearts were examined histologically.


RESULTS
Autonomic nerve stimulation led to decreased atrial refractoriness and increased AF inducibility and duration. Each of these effects were attenuated following pulmonary vein encircling (e.g., mean ERP decreased before (-23.7 +/- 1.8, p < 0.001) but not after ablation (-2.3 +/- 1.9, p = 0.25); AF inducibility increased by 26% before vs. 5% after ablation). No attenuation was seen in the sham operated animals. Histologic analysis following pulmonary vein encircling demonstrated destruction of some but not all autonomic ganglia.


CONCLUSIONS
Autonomic stimulation shortens atrial refractory periods and potentiates AF. Pulmonary vein encircling ablation partially destroys atrial autonomic inputs, attenuates the refractory period shortening effect of autonomic stimulation and decreases AF inducibility. Destruction of autonomic ganglia may contribute to the anti-fibrillatory effects of pulmonary vein encircling and warrants further investigation.
Spector
Peter Salem
PS
Department of Medicine, Cardiovascular Research Institute, University of Vermont College of Medicine, and Fletcher Allen Health Care, Burlington, VT 05401, USA. peter.spector@vtmednet.org
Noori
Arshia Mehdi
AM
Hardin
Nicholas Jackson
NJ
Calame
James Daniel
JD
Bell
Steve Paul
SP
Lustgarten
Daniel Lawrence
DL
D000273:Adipose Tissue / Q000294:innervation; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000601:surgery*; D017776:Autonomic Pathways / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000379:methods*; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000503:physiopathology*; D011667:Pulmonary Veins