Effects Of Fast Pathway Ablation On The Concealment Zone And Electrophysiological Behavior Of AV-Node During Atrial Fibrillation.

Objectives: Dual pathways have a determinant role in the occurrence of atrio nodal tachyarrhythmia (AVNRT). The aim of present study is to determine the role of slow pathway (SP) in the concealment zone and protective role of AV node during atrial fibrillation (AF). Material &Methods: In 7 isolated nodal rabbit preparation zone of concealment and concealed conduction is quantified by Specific pacing protocols. The differences between effective refractory period of atrial and AV node in the basic cycle length and after introducing concealed beat was considered as Zone of concealment. AَF was simulated by high-rate atrial pacing with random coupling intervals. Small miniature lesions were made in superior compact node by delivering constant voltage100-110 v. Results: FP ablation resulted in longer minimum nodal conduction time, but without change of nodal effective and functional refractory period. Zone of concealment was determined as 10±4.8 ms. After fast pathway modification nodal characteristics during AF did not change significantly (average H–H intervals, number of concealed beats and zone of concealment). Conclusion: Fast pathway has not a determinant role in the mechanism of concealed conduction and zone of concealment. During AF, the wave fronts did not used fast pathway to conduct to ventricles.