MULTIPLE ANTEROGRADE ATRIOVENTRICULAR NODE PATHWAYS IN PATIENTS WITH ATRIOVENTRICULAR NODE REENTRANT TACHYCARDIA

Objectives. This study sought to investigate electrophysiologic charac teristics and possible anatomic sites of multiple anterograde slow atr ioventricular (AV) node pathways and to compare these findings with th ose in dual anterograde AV node pathways. Background. Although multipl e anterograde AV node pathways have been demonstrated by the presence of multiple discontinuities in the AV node conduction curve, the role of these pathways in the initiation and maintenance of AV node reentra nt tachycardia (AVNRT) is still unclear, and possible anatomic sites o f these pathways have not been reported. Methods. This study included 500 consecutive patients with AVNRT who underwent electrophysiologic s tudy and radiofrequency ablation. Twenty-six patients (5.2%) with trip le or more anterograde AV node pathways were designated as Group I (16 female, 10 male, mean age 48 +/- 14 years), and the other 474 patient s (including 451 with and 23 without dual anterograde AV node pathways ) were designated as Group II (257 female, 217 male; mean age 52 +/- 1 6 years). Results. Of the 21 patients with triple anterograde AV node pathways, AVNRT was initiated through the first slow pathway only in 3 , through the second slow pathway only in 8 and through the two slow p athways in 9. Of the five patients,vith quadruple anterograde AV node pathways, AVNRT was initiated through all three anterograde slow pathw ays in three and through the two slower pathways (the second and third slow pathways) in two, After radiofrequency catheter ablation, no pat ient had inducible AVNRT. Eleven patients (42.3%) in Group I had multi ple anterograde slow pathways eliminated simultaneously at a single ab lation site. Eight patients (30.7%) had these slow pathways eliminated at different ablation sites; the slow pathways with a longer conducti on time were ablated more posteriorly in the Koch's triangle than thos e with a shorter conduction time. The remaining seven patients (27%) h ad a residual slow pathway after delivery of radiofrequency energy at a single or different ablation sites. The patients in Group I had a lo nger tachycardia cycle length, poorer retrograde conduction properties and a higher incidence of multiple types of AVNRT than those in Group II. Conclusions. Multiple anterograde AV node pathways are not rare i n patients with AVNRT, However, not all of the anterograde slow pathwa ys were involved in the initiation and maintenance of tachycardia. Rad iofrequency catheter ablation was safe and effective in eliminating cr itical slow pathways to cure AVNRT.