RADIOFREQUENCY CATHETER ABLATION FOR AV NODAL REENTRY - A TECHNIQUE FOR RAPID TRANSECTION OF THE SLOW AV NODAL PATHWAY

Transection of the Slow AV Nodal Pathway. Selective radiofrequency (RF ) catheter ablation of the slow AV nodal pathway has shed new light on the anatomy and physiology of the atrioventricular junction. The reco rding of ''slow pathway potentials'' facilitates localization of the s low pathway and has led to a concept of multiple pathway components wi th atrial insertion sites covering a potentially broad region surround ing the coronary sinus os. The critical area for complete interruption of the slow pathway may be larger than lesion size produced by ablati on at a single site, resulting in multiple RF applications with length y sessions and prolonged radiation exposure. Information from both old and recent literature suggests that the slow AV nodal pathway is repr esented by a group of fibers originating from the posteroinferior inte ratrial septum and coursing anterosuperiorly near the tricuspid annulu s before converging upon the compact AV node. Based on this anatomical arrangement, the present study was conducted to evaluate a technique designed to transect the slow pathway by producing a linear RF lesion perpendicular to the orientation of the slow pathway within the mid-po rtion of Koch's triangle. Using this technique, 30 of 30 patients with common AV nodal reentry were rendered noninducible using 1 to 3 RF ap plications. Total procedure time averaged 3.4 +/- 1.1 hours and fluoro scopy time averaged 14.8 +/- 4.6 minutes. As a marker of efficacy, epi sodic nonsustained atrial tachycardia (NSAT) during RF delivery occurr ed in 28 of 30 (93%) successful applications. Three patients experienc ed tachycardia recurrence and were successfully ablated by repeat proc edure. Conduction characteristics and refractoriness of the fast pathw ay were unchanged in 23 of 23 patients reevaluated at a mean of 7.2 we eks postablation. Two of 30 (6%) patients experienced procedure relate d complications but there were no instances of AV block. We conclude t hat the technique of producing a linear lesion by continuous migratory RF application in the manner described safely and effectively elimina tes AV nodal reentry, simplifies the procedure, and minimizes radiatio n exposure to the patient and the physician.