The Electrophysiologic Mechanism And Radiofrequency Catheter Ablation Of Multiple Forms Of Atrioventricular Nodal Reentrant Tachycardia

Background and Objective Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal regular supraventricular tachycardia.Radiofrequency catheter ablation is a good method of eliminating AVNRT.The mechanism and catheter ablation of multiple forms of atrioventricular nodal reentrant tachycardias have not been well investigated. The purpose of this study was to analyze the electrophysiologic mechanism and the results of catheter ablation in patients with multiple forms of AVNRT.Method Eighteen patients with multiple forms of AVNRT(≥2 forms) underwent electrophysiological study and catheter ablation were studied.For ablation of slow/fast and slow/slow AVNRT,the antegrade slow pathway(right posterior extension of the AV node) was initially targeted.For ablation of fast/slow AVNRT,radiofrequency current was initially directed at the site with earliest retrograde atrial activation during slow pathway conduction.The end points of ablation were elimination of 1:1 antegrade slow pathway conduction and retrograde slow pathway conduction participated in AVNRT,and especially uninducibility of any form of AVNRT.Result The incidence of multiple forms of AVNRT was 1.8%(18/1000). Among the 18 patients,2 forms of AVNRT could be induced before ablation in 11 patients,and the second form of AVNRT could only be induced after ablation of the first form of AVNRT in the other 7 patients.In the 11 patients with induced multiple forms of AVNRT before ablation,ablation between the tricuspid annulus and the coronary sinus ostium(right posterior extension) successfully eliminated multiple forms of AVNRT in all the 11 patients.In the other 7 patients,the second form of AVNRT was eliminated after further extensive ablation between the tricuspid annulus and the coronary sinus ostium (right posterior extension) in 4 patients,and the left posterior extension(within the proximal CS and at the atrial aspect of the proximal mitral annulus) need to be ablated to eliminate the second form of AVNRT in 2 patients.In 1 case of the 7 patients,the left posterior extension were ablated to eliminate both two forms of AVNRT.There were no AV block and other important complications. There was no recurrence of AVNRT in the period of follow-up.Conclusion In most patients with multiple forms of AVNRT,the main substrate might be the right posterior extension of the AV node using antegrade and retrograde conduction separately during different forms of AVNRT. Therefore targeting the right posterior extension would eliminate multiple forms of AVNRT in most patients.In few patients with multiple forms of AVNRT, both the right and left posterior extensions might be involved in different forms of AVNRT,and ablation of both the posterior extensions might be needed to eliminate multiple forms of AVNRT.