UNLABELLED: The purpose of this study was to examine the electrophysiological determinants of the elimination of recurrent atrioventricular nodal reentrant tachycardia (AVNRT) despite the persistence of dual AV nodal pathway physiology or single echo beats after ablation procedures. The study included 26 patients with common AVNRT who had undergone successful ablation treatment and no long-term recurrence of AVNRT. The slow pathway potential was targeted, and the endpoint of ablation was one echo during atrial extrastimulus testing (ET) with isoproterenol. Persistent dual pathways physiology or single echoes were present in 12 patients (group I) and absent in 16 (group II) after ablation. The number of anterograde AV nodal pathways and maximum AH interval (Max AH) during ET were measured before and after ablation, and ventriculoatrial conduction during ventricular pacing was examined. RESULTS: (1) multiple AV nodal pathways were more frequently observed in group I than in group II (50.0% vs 7%, P < 0.05); (2) Max AH decreased significantly after ablation in both groups (309 +/- 157 vs 171 +/- 53 ms in group II; P < 0.01, and 409 +/- 65 vs 274 +/- 86 ms in group I; P < 0.001); and (3) retrograde dual pathway conduction was more common in group I than in group II. These data suggest the presence of nonuniform conductive properties of the AV node in group I and that ablation targeting the slow pathway potential prevents recurrences of AVNRT by eliminating the pathway with the longest conduction time.
UNLABELLED: The purpose of this study was to examine the electrophysiological determinants of the elimination of recurrent atrioventricular nodal reentrant tachycardia (AVNRT) despite the persistence of dual AV nodal pathway physiology or single echo beats after ablation procedures. The study included 26 patients with common AVNRT who had undergone successful ablation treatment and no long-term recurrence of AVNRT. The slow pathway potential was targeted, and the endpoint of ablation was one echo during atrial extrastimulus testing (ET) with isoproterenol. Persistent dual pathways physiology or single echoes were present in 12 patients (group I) and absent in 16 (group II) after ablation. The number of anterograde AV nodal pathways and maximum AH interval (Max AH) during ET were measured before and after ablation, and ventriculoatrial conduction during ventricular pacing was examined. RESULTS: (1) multiple AV nodal pathways were more frequently observed in group I than in group II (50.0% vs 7%, P < 0.05); (2) Max AH decreased significantly after ablation in both groups (309 +/- 157 vs 171 +/- 53 ms in group II; P < 0.01, and 409 +/- 65 vs 274 +/- 86 ms in group I; P < 0.001); and (3) retrograde dual pathway conduction was more common in group I than in group II. These data suggest the presence of nonuniform conductive properties of the AV node in group I and that ablation targeting the slow pathway potential prevents recurrences of AVNRT by eliminating the pathway with the longest conduction time.