Abstract 12985: Mechanism of the Electrogram Fractionation Observed in the Pulmonary Vein Antrum during Atrial Fibrillation: Analysis of Activation Using Contact and Non-Contact Mapping
Background: Fractionated atrial electrograms observed in the pulmonary vein (PV) antrum during atrial fibrillation (AF) is considered to derive from the local high frequent rotor activation, however it was not necessarily observed continuously. Furthermore, the difference in the activation at PV antrum between the periods with and without fractionated electrgrams is unclear.
Objective: The purpose of this study was to define the mechanism of the electrogram fractionation observed in PV antrum during AF.
Methods: Endocardial mapping of the left superior PV antrum was performed in 12 patients with paroxysmal AF. The contact electrograms of the PV antrum were recorded by the 20-pole circular catheter and the activation sequence of this region was analyzed using 3D non-contact mapping system (Ensite 3000). The activation sequences in PV antrum were compared among 3 phases in which the contact electrograms show the organized, transitional, and fractionated morphologies.
Results: There was no significant difference in the frequency of focal discharge among 3 phases (organized; 0.2±0, transitional; 0.1±0, and fractionated; 0.2±0 times/sec, p=NS). The number of rotational reentry during fractionated and transitional phases were higher than that during organized phase (3.3±0.4 vs. 1.9±0.6, p=0.002 and 3.7±1.0 vs. 1.9±0.6 times/sec, p=0.003). The number of functional block in fractionated phase was higher than that in organized phase (7.1±2.3 vs. 3.3±3.3 times/sec; p<0.01), but there was no difference between fractionated and transitional phases. The length of the functional block in fractionated and transitional phases were both significantly shorter than that in organized phase (10.3±3.9 vs. 18.3±6.0 mm, p=0.006 and 7.0±2.8 vs. 18.3±6.0 mm, p=0.02). Prevalence of functional block, including during rotational reentry, in the superior and anterior PV antra was higher than that in the inferior and posterior PV antra (3.3±3.6, 3.2±3.8, 0±0 and 0.3±1.0, times/sec, p<0.001).
Conclusions: Fractionated electrograms in the PV antrum were caused by the local rotational reentry and frequent episodes of local conduction block with shorter block line. These rotational and localized activations were frequently observed in the superior and anterior PV antrum.
- © 2012 by American Heart Association, Inc.