Accelerated junctional rhythm (JR) is known as a response of the atrioventricular node to thermal injury and a common finding in radiofrequency ablation for AV node reentrant tachycardia. We studied JR during 1314 radiofrequency current deliveries in 172 patients with AV node reentrant tachycardia or paroxysmal atrial fibrillation in relation to the ablation result. JR in a successful RF delivery were characterized by cycle length and conduction.
Results: Selective slow pathway ablation was performed in 100 patients (Group A), selective fast pathway ablation in 41 patients (Group B), and total AV junction ablation in 31 patients (Group C). A successful radio-frequency ablation without JR was rare (sensitivity: 98.8%; specificity: 51.2%). JR during slow pathway ablation had a longer cycle length (X +/- SD; CL: 494 +/- 138 ms) and a lower cycle length dispersion (delta CL: 178 +/- 199 ms) than JR during fast pathway ablation (CL: 399 +/- 108 ms; delta CL: 345 +/- 145 ms) or before total AV block (CL: 439 +/- 163 ms; delta CL: 338 +/- 195 ms). JR with bundle branch block aberration or ventriculoatrial block were more often found in group B and group C than in group A (BBB: 29% vs. 23% vs. 12%; VA-Block: 80% vs. 82% vs. 33%). Group B and group C did not differ significantly.
Conclusion: JR leading to fast pathway ablation or heralding total AV block are characterized by a short cycle length, wide cycle length dispersion, and predominantly present ventriculoatrial block. Thus, JR is a useful marker to prevent inadvertent AV block in slow pathway ablation.