Radiofrequency Catheter Ablation of Atriofascicular Accessory Pathways Guided by Discrete Electrical Potentials Recorded at the Tricuspid Annulus

Abstract

Recording of discrete electrical potentials at the tricuspid annulus identifies an optimal ablation site where radiofrequency current can safely eliminate conduction through atriofascicular accessory pathways with Mahaim-like properties.

Catheter ablation of atriofascicular Mahaim fibers guided by the activation potential

“…With the evolution of electrophysiology, more satisfactory results were obtained, aiming at the ablation of the atrial insertion of these fibers [9][10][11][12][13] . Because its distal insertion is not located adjacent to the tricuspid ring, as with the accessory atrioventricular pathways (Wolff-ParkinsonWhite syndrome), mapping the earliest ventricular activation in regard to QRS is useless in these cases.…”

“…1 -Continuous programmed stimulation in high right atrium showing: (1A) with a stimulation cycle (S1-S1) of 460 ms, mild ventricular preexcitation occurs (*); (1B) continuing the tracing, progressive ventricular preexcitation is observed during the stimulation at progressively shorter cycles (S1-S1=390 ms) (**) with extension of the A-H and A-V intervals. pharmacological treatment, catheter ablation 5,6,[9][10][11][12]18 , and surgery 7,12 . The first experiences with catheter ablation used high-energy shocks in the atrioventricular node region.…”

“…In addition, because these fibers do not have retrograde conduction, mapping the ventriculoatrial conduction is not possible. Therefore, the following special techniques for mapping these fibers were reported: 1) mapping atrial extrastimuli along the tricuspid ring to identify the shortest spike-Delta interval (pace-mapping); 2) release of extrastimuli along the tricuspid ring during antidromic tachycardia searching for the point of the greatest "advancement" (preexcitation) of the subsequent QRS; and 3) mapping the fiber activation potential in sinus rhythm [9][10][11][12][13][14] . Klein et al 9 reported on 4 patients who underwent ablation with pace-mapping in the atrium.…”

“…The criteria for the diagnosis of Mahaim fiber were as follows: absence of ventricular preexcitation in sinus rhythm or discrete preexcitation with left bundle-branch block morphology; presence of progressive ventricular preexcitation during continuous atrial stimulation associated with an increase in the A-V interval and a reduction in the H-V interval; induction of antidromic atrioventricular tachycardia with left bundle-branch block morphology, this morphology being similar to that of maximum preexcitation 9,10,[11][12][13][14][15][16] . Bardy et al 17 described typical Mahaim tachycardia as follows: 1) left bundle-branch block morphology; 2) QRS axis superior to or between 0º and 75º; 3) presence of R wave in D1; 4) presence of rS in V1; and 5) QRS transition in V4 or after V4.…”

“…Recently, most of these pathways have been classified as atriofascicular fibers that connect the right atrium to distal portions of the right branch of the His bundle with decremental properties 7,8 . Because they have different anatomical and electrophysiological characteristics, the following special ablation techniques have been considered: 1) atrial stimulation (pace-mapping) along the tricuspid ring, looking for the shortest "spike-Delta" interval 9 ; 2) mapping with extrastimuli during antidromic tachycardia, searching for the point of greatest "preexcitation" of the subsequent QRS; and 3) mapping of the activation potential of the fiber in sinus rhythm [10][11][12][13] . The latter has been considered more precise than the others; however, due to the rarity of this type of fibers, little experience has been reported in the medical literature.…”