Radiofrequency catheter ablation for AV nodal reentry: a technique for rapid 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 recording of "slow pathway potentials" facilitates localization of the slow pathway and has led to a concept of multiple pathway components with atrial insertion sites covering a potentially broad region surrounding the coronary sinus os. The critical area for complete interruption of the slow pathway may be larger than lesion size produced by ablation at a single site, resulting in multiple RF applications with lengthy sessions and prolonged radiation exposure. Information from both old and recent literature suggests that the slow AV nodal pathway is represented by a group of fibers originating from the posteroinferior interatrial septum and coursing anterosuperiorly near the tricuspid annulus 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-portion of Koch's triangle. Using this technique, 30 of 30 patients with common AV nodal reentry were rendered noninducible using 1 to 3 RF applications. Total procedure time averaged 3.4 +/- 1.1 hours and fluoroscopy time averaged 14.8 +/- 4.6 minutes. As a marker of efficacy, episodic nonsustained atrial tachycardia (NSAT) during RF delivery occurred in 28 of 30 (93%) successful applications. Three patients experienced tachycardia recurrence and were successfully ablated by repeat procedure. Conduction characteristics and refractoriness of the fast pathway were unchanged in 23 of 23 patients reevaluated at a mean of 7.2 weeks postablation.(ABSTRACT TRUNCATED AT 250 WORDS)