Electrophysiologic properties of pulmonary veins assessed using a multielectrode basket catheter Original Research Article

Objectives The purpose of the present study was to evaluate the electrophysiologic properties within the pulmonary vein (PV) and at the PV–left atrial (LA) junction. Background It has been recognized that atrial fibrillation (AF) can originate from PVs. However, the electrophysiologic properties of the PV have not been well characterized. Methods Thirty-two bipolar electrograms were recorded simultaneously from a basket catheter placed in 81 PVs of 48 patients with paroxysmal AF. The programmed stimulation was performed in the distal PV and PV-LA junction. Activation maps of PVs were analyzed from episodes of spontaneous onset of AF and initiation of induced AF by a single extrastimulus. Results The effective refractory period (ERP) of the distal PV was significantly shorter than that of the PV-LA junction (177 ± 43 vs. 222 ± 30 ms, p < 0.0001). The conduction delay from the distal PV to the PV-LA junction was significantly longer than that from the PV-LA junction to distal PV (73 ± 40 vs. 32 ± 17 ms, p < 0.0001). During initiation of AF, a short coupled extrastimulus or rapid, repetitive focal activities originating from the PV formed a PV-LA reciprocating re-entrant circuit involving exit and entrance breakthrough points at the PV-LA junction. Also, an unstable re-entrant circuit within the PV was observed. Conclusions The presence of ERP heterogeneity and anisotropic conduction properties within the PV and at the PV-LA junction may be crucial to promote re-entry formation and thus might play an important role as a substrate for the maintenance of AF.