Optimal target site for slow AV nodal pathway ablation: Possibility of predetermined focal mapping approach using anatomic reference in the Koch's triangle

Optimal Target Site for Slow A.V Nodal Pathway. Introduction: Although a va riety of ablation techniques have been developed in the treatment of atriov entricular nodal reentrant tachycardia (AVNRT), there have been few reports discussing the location of the optimal target site, Based on our early exp eriences, we hypothesized that radiofrequency (RF) current applied around t he upper margin of the coronary sinus ostium (UCSO) results in the most eff ective and safe treatment of AVNRT, Methods and Results: To confirm our hypothesis, the efficacy of RF currents applied around the UCSO guided by local electrograms in 59 patients (group B: predetermined focal mapping approach) were compared with the outcomes i n 60 other patients previously treated with the standard electrogram-guided mapping method starting around the lower margin of the coronary sinus osti um (group A), The precise location of ablation catheters at successful site s (S) was also evaluated, All the patients were successfully treated withou t complications, Significantly fewer RF pulses and lower energies were need ed in group B patients (mean RF applications: 4.3 vs 1.4 applications, mean total energy delivered: 4,699 vs 2,236 J in groups A and B, respectively, P < 0.01). Detailed analyses of the anatomical locations of S using CS veno graphy in group B patients who received only a single RP application (46 pa tients) revealed that the distance between His and S varied according to th e length of Koch's triangle, while that between S and UCSO was relatively c onstant. In 85% of these 46 patients, S was located within 5 mm above and b elow the level of the UCSO, Conclusion: RF applications around the UCSO guided by Local electrograms yi elded excellent outcomes in AVNRT patients with wide varieties in the size of Koch's triangle, The optimal target site was located within 5 mm above a nd below the level of UCSO along the tricuspid annulus.