Surgical approach to anterior septal accessory pathways in 20 patients with the Wolff-Parkinson-White syndrome

Right anterior septal accessory pathways in the Wolff-Parkinson-Whitesyndrome are generally defined by electrophysiological criteria, the mostimportant being that earliest retrograde atrial activation during AVreciprocating tachycardia occurs at the anterior medial segment of thetricuspid annulus (His bundle catheter). The purpose of our study is todescribe intraoperative mapping in 20 patients with anterior septalaccessory pathways, and to assess if intraoperative mapping contributes tothe operative approach. At surgery, all patients had identical earlyventricular activation during pre-excitation at the infundibulum. However,two groups could be identified on the basis of retrograde atrial epicardialactivation during AV reciprocating tachycardia or right ventricular pacing.Group 1 comprised 16 patients with earliest activation at the interatrialseptum adjacent to the His bundle. Epicardial dissection failed to affectaccessory pathway conduction. The accessory pathway was only ablated when adiscrete endocardial approach to the atrial septum was used. Group 2comprised 4 patients with early atrial activation "paraseptally" in theright coronary fossa. These accessory pathways were ablated by anepicardial approach without using cardiopulmonary bypass. We conclude thatright anterior septal accessory pathways as defined by electrophysiologicalcriteria can be divided into two groups on the basis of the atrialactivation sequence: (1) right septal accessory pathways in the septalpara-Hissian region and (2) right anterior 'paraseptal' accessory pathways.This classification is of practical importance because the latter can beablated using an epicardial approach without the need for cardiopulmonarybypass or atriotomy.