Patterns of accelerated junctional rhythm during slow pathway catheter ablation for atrioventricular nodal reentrant tachycardia: Temperature dependence, prognostic value, and insights into the nature of the slow pathway

Slow Pathway Accelerated Junctional Rhythm. Introduction: Although accelera ted junctional rhythm (AJR) is a known marker for successful slow pathway ( SP) ablation sites, AJR may just be a regional effect of the anisotropic co nduction properties of this area of the heart. We believe that detailed ass essment of the AJR might provide insight into the SP specificity of this AJ R and perhaps the nature of the SP itself. Methods and Results: Our ablation protocol consisted of 30-second, 70 degre es C temperature-controlled ablation pulses with assessment after each puls e. Serial booster ablations were performed at the original successful site and at least 2 to 3 nearby sites to assess for residual AJR after the proce dure in 50 consecutive SP ablations, We defined three distinct patterns of AJR: continuous AJR that persisted until the end of energy delivery (group I, 25 patients); alternating or "stuttering" AJR that persisted throughout energy delivery (group II, 9 patients); and AJR that ended abruptly during energy delivery (group III, 16 patients). Mean ablation temperatures in the three groups was 57 degrees +/- 5 degrees C, 54 degrees +/- 5 degrees C, a nd 63 degrees +/- 5 degrees C, respectively (P = 0.0002 for groups I and II vs group III). Ten of 34 (29%) patients in groups I and II ("low-temperatu re ablation") exhibited residual SP (Jump and/or single echo beats) despite tachycardia noninducibility, and 25 of 34 (73%) patients had residual AJR during the booster ablations, but neither of these was seen in any group II I patients. Conclusion: Ablation temperature correlates with the pattern of AJR produce d during SP ablation, That higher temperature lesions simultaneously abolis h all SP activity as well as the focus of AJR suggests that this AJR is spe cific for the SP and is not a nonspecific regional effect.