Successful radiofrequency ablation of a parahisian accessory pathway from the right coronary cusp

Abstract

A 46-year-old female presented with narrow-complex tachycardia related to type B pre-excitation pattern consistent with a parahisian AP (Fig. 1A ). During electrophysiology study, orthodromic atrioventricular reentry tachycardia was easily and reproducibly induced. Electroanatomic mapping of the right atrium demonstrated the earliest ventricular activation adjacent to the His bundle, which was 20 ms preceding the delta-wave onset (Fig. 2C and F ). A radiofrequency energy application at this site resulted in transient conduction block of the AP (power control mode; max cut-off = 15 W, 24 s), and was interrupted due to the occurring of junction rhythm. A large His bundle potential of 0.2 mV was inscribed during AP conduction block (Fig. 1E) at the same site. Considering the too close proximity of the atrioventricular conduction to the AP, no more attempts of ablation from the right side were continued, and the coronary cusps were then mapped retrogradely. Aortic root angiography was performed to precisely anatomic relation with the His bundle position (Fig. 2A and D). The earliest ventricular activation at the right coronary cusp was 30 ms from the onset of the delta wave (Fig. 1F). At this site, a small atrial activity followed by an early fragmented ventricular electrograms which preceded by a pre-potential was recorded. Mechanical bumping of the AP was observed during manipulating the mapping catheter. The application of radiofrequency energy at this site eliminated the AP within seconds (power control mode; max cut-off = 25 W) (Figs. 1E, 2B, C, E and F). At 6-month follow-up, there was no evidence of recurrent symptoms or pathway conduction. Fig. 2Aortic root angiogram in the left (45°) and right (30°) anterior oblique view (A and D). The ablation catheter is located at the successful site in the left (45°) and right (30°) anterior oblique view (B and E). Electroanatomic mapping of right atrium and aortic root in the left (45°) and right (30°) anterior oblique view (C and F). CS = coronary sinus; LAO = left anterior oblique; LCC = left coronary cusp; NCC = noncoronary cusp; RAO = right anterior oblique; RCC = right coronary cusp; RVA = right ventricular apex. View Large Image Figure Viewer Download Hi-res image