Catheter technique for ablation of accessory atrioventricular pathway: long-term results

Catheter ablation of an accessory atrioventricular pathway was attempted in six patients with recurrent tachyarrhythmias resistant to medication (four to five trials). Localization of the accessory pathway was performed by potential recordings with an electrode catheter from the region of the tricuspid and mitral valve rings during orthodromic supraventricular tachycardia (n = 4), during sinus rhythm (n = 1), and during ventricular pacing (n = 1). Using this mapping technique, the site of earliest atrial or ventricular activation through the accessory pathway was localized in the anterior septal (n = 2), right free wall (n = 2), posterior septal (n = 2), or left free wall (n = 1) region of the atrioventricular valve rings. The shortest ventriculo-atrial (VA) and atrio-ventricular (AV) intervals measured in the local electrograms ranged from VA = 45-70 ms, and AV = 45-65 ms, respectively. The accessory pathway responsible for the arrhythmia demonstrated exclusive retrograde (n = 4) or bidirectional (n = 2) conduction properties. A total of 13 direct-current transcatheter shocks (one to three per patient) of 20-200 J each were aimed at the site of the accessory pathway. Thereby, conduction through the accessory pathway was abolished (n = 5) or modified (n = 1) and the patients were freed from their syncope and disabling arrhythmias (follow-up: 4.6-5.9 years). The procedure was well tolerated without complications. Mapping-guided catheter ablation of accessory pathways is an effective treatment of refractory supraventricular tachyarrhythmias in selected patients.