We compared the effects of Na⁺ channel blockers on the electrophysiological properties in the isolated pulmonary vein-left atrium connected preparation from guinea pig. Four concentric electrodes were attached to the pulmonary vein and left atrium to measure the intra-pulmonary vein and intra-atrial conduction velocity and the effective refractory period. Pilsicainide (10 µM), a Na⁺ channel blocker, decreased the conduction velocity and prolonged the effective refractory period in both regions. GS-458967 (1 µM) and eleclazine (10 µM), known as Na⁺ channel blockers at open and inactivated states, prolonged the effective refractory period in the pulmonary vein but not in the left atrium without affecting the conduction velocity in both regions. The wavelength, calculated by the conduction velocity × the effective refractory period, in the pulmonary vein was prolonged by GS-458967 and eleclazine but shortened by pilsicainide, while these drugs did not prolong that in the left atrium. These results suggest that certain types of Na⁺ channel blockers, such as GS-458967 and eleclazine, appear to be effective therapeutic agents for atrial fibrillation in which the reentrant excitation in the pulmonary vein is important.