Ablation and procedure endpoints
Three-dimensional electro-anatomical mapping systems (Carto 3, Biosense Webster, Diamond Bar, CA, US and Ensite NAVX, Abbott, Minneapolis, MN, US) were used for these procedures. Temperature-controlled ablation catheters (Navistar, Biosense Webster, Diamond Bar, CA, US and Safire, Abbott, Minneapolis, MN, US) were applied (55-60°C, 40-50 W, 90-120 seconds). The ablation targets located on the AV nodal slow pathway area, within the lower one third of the triangle of Koch.
If the patients had passed EPS after initial ablation without any evidence of AP, they then underwent an adenosine triphosphate (ATP) test. Ventricular backup pacing by the RVA catheter was ready for protection against slow ventricular rhythm during the ATP test. An ATP bolus of 30 mg was then injected rapidly via peripheral vein to block the AV node. When AV nodal block was observed without antegrade A-V nodal conduction nor pre-excitation, ventricular pacing was further performed to exclude retrograde V-A conduction via a concealed AP. The procedure was concluded after confirmation by both EPS and the ATP test.