Sequential Abolition of Antegrade and Retrograde Conduction in Wolff-Parkinson-White Syndrome: A Case Series.

BACKGROUND Radiofrequency ablation in cases of Wolff-Parkinson-White (WPW) syndrome is a relatively safe procedure that yields good results. However, the electrical characteristics of WPW syndrome have not yet been fully elucidated. Herein, we report 2 cases of WPW syndrome, wherein antegrade conduction was abolished first, followed by retrograde conduction. CASE REPORT Case 1: A 15-year-old boy who recently reported experiencing frequent palpitations was diagnosed with type A WPW syndrome by electrocardiography (ECG). Radiofrequency energy was delivered to the earliest activation site using an ablation catheter. This procedure abolished antegrade accessory pathway conduction in 6 seconds, and then the ablation was continued for 60 seconds; however, retrograde accessory pathway conduction remained intact. Hence, radiofrequency ablation was performed to further deliver radiofrequency energy to abolish the retrograde accessory pathway conduction. Case 2: A 19-year-old woman with palpitations since elementary school was diagnosed with type A WPW syndrome by ECG. Radiofrequency energy was delivered to the earliest activation site through an ablation catheter to abolish antegrade accessory pathway conduction in approximately 1 second, and then the ablation was continued for 60 seconds. Retrograde accessory pathway conduction was preserved, and further radiofrequency ablation performed multiple times in the same vicinity abolished retrograde accessory pathway conduction. CONCLUSIONS We managed 2 cases of WPW syndrome wherein antegrade and retrograde accessory pathway conduction were individually abolished. This phenomenon may have been caused by an incomplete lesion that resulted in a functional block.