Objective: The aim of this study was to evaluate our results of radiofrequency catheter ablation (RFCA) of concealed accessory atrioventricular pathways (CP).
Patient selection: We treated with RFCA 19 patients, with 21 CP, 10 men and 9 women, mean age 37 +/- 16 years, with supraventricular tachycardia (SVT) and absence of ventricular pre-excitation in the electrocardiogram (ECG). These patients comprised 50% of the patients who underwent RFCA for SVT and had no ventricular pre-excitation in the ECG. The diagnosis of CP was made by electrophysiologic study, based on the demonstration of a pathway capable of retrograde conduction only.
Methods: The RFCA was performed without antiarrhythmic drugs in the same session of the electrophysiologic diagnosis. The location of the CP site was obtained by catheter mapping, looking for the earliest atrial retrograde activation during tachycardia or ventricular pacing.
Results: The CP had a right-sided location in only 2 patients who had an incessant form of SVT, the CP in these patients exhibit decremental conduction--permanent junctional reciprocating tachycardia. In the other patients the CP was left-sided, lateral in 11 patients, posterior in 3, postero-septal in 3 and medial septal in one patient. In 9 patients there was a simultaneous ventricular activation in the his bundle electrogram and in the electrogram of the ablation site, suggesting partial anterograde penetration of the stimuli on the accessory pathway. Success criteria were achieved in 18 patients (95%) corresponding to 20 CP.
Conclusions: The prevalence of CP in the presence of SVT without ventricular pre-excitation is high, almost all left-sided. The CP displays eccentric atrial activation during SVT. It is possible that CP are capable of partial anterograde conduction as well. The success rate of RFCA is high.