Electrophysiological Characteristics and Radiofrequency Catheter Ablation of Accessory Pathway Connecting the Right Atrial Appendage and the Right Ventricle.

BACKGROUND: The accessory pathway (AP) connecting the right atrial appendage (RAA) and the right ventricle (RV) is rare. OBJECTIVE: We sought to investigate the feature of the AP connecting the RAA and the RV and the efficacy of radiofrequency catheter ablation via the endocardial access. METHODS: We retrospectively analyzed 14 consecutive patients with 14 APs connecting the RAA and the RV managed by 15 procedures between January 2003 and December 2014. RESULTS: Ten patients presented as preexcitation during sinus rhythm. All APs had retrograde conduction. None had either antegrade or retrograde decremental conduction property. Ablation targeting the sites at the tricuspid annulus failed in all patients. They were successfully managed by ablating the atrial insertion sites with a median of 10.5 (range 5-28) radiofrequency applications. Electrograms at the successful target showed high amplitude atrial electrogram and low amplitude or no ventricular electrogram. The atrial insertion sites were at the floor of the RAA in 10 patients and inside the lower lobe of the RAA in the remaining 4 patients. The shortest distance between the successful target and the tricuspid annulus in the right anterior oblique projection was 19.7 ± 4.0 mm. There were no complications or recurrences during a median follow-up period of 4.3 (range 0.2-11.8) years. CONCLUSION: The APs connecting the RAA and the RV had typical conduction properties. The atrial insertion site favored the floor and the lower lobe of the RAA. Ablation targeting the atrial insertion sites was effective and safe, albeit multiple radiofrequency applications were needed.

Frequency of fractionated ventricular activation and atrial/ventricular electrogram amplitude ratio at successful ablation target of accessory pathways in patients with Ebstein's anomaly.

INTRODUCTION: Knowledge about local electrogram and atrial/ventricular electrogram amplitude ratio (A/V ratio) at the true atrioventricular ring for successful ablation of accessory pathways (APs) in patients with Ebstein's anomaly is limited. METHODS: Twenty-two adults with Ebstein's anomaly and APs were managed by 24 sessions of radiofrequency catheter ablation (RFCA). A right atrial/ventricular angiogram with or without 3-dimensional electroanatomic mapping was performed to delineate the true atrioventricular ring and atrialized right ventricle (ARV). Electrograms of successful targets were analyzed. For each right-sided AP target, 2 AP targets matched by location and conduction property from normal hearts were selected as controls, and their A/V ratios were compared. RESULTS: In 32 right-sided APs of all 22 patients, local ventricular activation at successful site presented as normal electrogram in 14, fractionated ventricular electrogram (FVE) in 16, and double ventricular potentials in 2. The bipolar voltage of ARV was markedly lower than in normal hearts. The A/V ratio at the successful target was significantly higher in APs with FVE than in control (1.64 ± 1.34 vs. 0.47 ± 0.19, P < 0.01), and was similar in APs with normal ventricular electrogram and in the control (0.38 ± 0.15 vs. 0.46 ± 0.15, P = 0.1726). The A/V ratio at the successful target with double ventricular potentials (after surgical correction) was 0.30 ± 0.20. All APs were successfully ablated without complications. CONCLUSIONS: In patients with Ebstein's anomaly, FVE was found in 50% of the successful targets of APs. High A/V ratio at successful sites with FVE and normal A/V ratio at targets with normal ventricular electrogram can facilitate target recognition and ablation.