ELECTROPHYSIOLOGIC CHARACTERISTICS AND ANATOMICAL COMPLEXITIES OF ACCESSORY ATRIOVENTRICULAR PATHWAYS WITH SUCCESSFUL ABLATION OF ANTEROGRADE AND RETROGRADE CONDUCTION AT DIFFERENT SITES

Introduction: Catheter ablation may eliminate anterograde and retrogra de accessory pathway conduction at closely adjacent but anatomically d iscrete sites. However, the mechanisms of this discrepancy, the electr ophysiologic and anatomical characteristics, and information about sys tematic study from a large patient population are not available. The p urpose of this study was to investigate the electrophysiologic charact eristics and anatomical complexities of the accessory pathway in which anterograde and retrograde conduction was successfully ablated at dif ferent sites. Methods and Results: Thirty-eight (10.9%) patients (19 m en and 19 women; mean age 37 +/- 2.4 years) fulfilling the criteria of having separate ablation sites for anterograde and retrograde conduct ion were designated as group I, and the other 310 patients (215 men an d 95 women; mean age 47 +/- 0.6 years) were designated as group II. Th e patients with right-sided free-wall pathways had the highest inciden ce (18.6%) of separate ablation sites. The anatomical distance between anterograde and retrograde directions (left anterior oblique view, 13 +/- 0.6 vs 8 +/- 0.9 mm, P < 0.01; right anterior oblique view, 17 +/ - 0.6 vs 5 +/- 0.7 mm, P < 0.01), and incidence of conduction impairme nt in one direction after successful ablation of another direction (15 % vs 78%, P < 0.05) differed significantly between left and right free -wall pathways. The mean distances obtained from left (7 +/- 0.4 vs 14 +/- 0.4 mm, P < 0.05) and right (7 +/- 1.1 vs 15 +/- 0.9 mm, P < 0.05 ) anterior oblique views were shorter in patients who had impairment o f conduction properties than those in patients without impaired conduc tion after successful ablation of one direction. Conclusions: This stu dy showed that anatomical and functional dissociation of the accessory pathway into anterograde and retrograde components was possible. Furt her study on the relation between electrophysiologic and pathologic ch aracteristics would be helpful to confirm these findings.