房室结折返性心动过速的可能折返机制和分型及其在指导慢径消融中的意义

目的根据房室结存在快径、右侧后延伸（经典慢径）和左侧后延伸（另一条慢径）和折返环路,对房室结折返性心动过速（AVNRT）进行分型,并根据电生理检查和射频消融的结果验证以上分型,同时分析此分型在指导房室结慢径消融中的意义.方法 812例入院进行射频消融AVNRT患者,常规行程序心房和心室电刺激和心内标测.根据AVNRT的类型分别采用消融房室结前传慢径和/或逆传慢径的方法治疗AVNRT.结果采用目前常用的AVNRT的分型方法,812例AVNRT患者中,慢快型659例（81%）、慢慢型81例（10%）、快慢型72例（9%）.所有812例AVNRT患者均消融或改良房室结慢径成功.按AVNRT可能的6种折返环路分型,慢快型649例（80%）、左侧变异慢快型10例（1%）、快慢型和变异快慢型57例（7%）、左侧变异快慢型15例（2%）、慢慢型81例（10%）.结论按房室结快径、右侧后延伸和左侧后延伸可能形成的6条折返环路,对AVNRT进行分型,符合电生理检查和射频消融的结果.此分型对理解AVNRT的折返机制和指导房室结慢径消融治疗AVNRT有较大的意义.

The multiple possible reentrant circuits and forms of atrioventricular nodal reentrant tachycardia: the significance in ablation of slow pathway

Objective Atrioventricular node may have three pathways, including fast pathway, rightward posterior extension and leftward posterior extension. Theoretically, any two of the three pathways should have the opportunity to form bi-directional reentrant circuits so that atrioventricular nodal reentrant tachycardia (AVNRT) might have six different reentrant circuits. Up to now, it is not clear whether all these reentrant circuits exist clinically. The purposes of this study are to type different forms of AVNRT according to the possible reentrant circuits and to investigate the advantage of this methodology in ablation of slow pathway (SP) to eliminate AVNRT. Methods Eight hundred and twelve patients with AVNRT were referred for ablation. Multipolar electrode catheters were advanced to coronary sinus, right atrium, His bundle and right ventricle. The remaining catheter was a deflectable ablation catheter used for mapping and ablation. According to different forms of AVNRT, the antegrade SP and/or retrograde SP were targeted for treating AVNRT. Results Using the definition commonly used now to type AVNRT, of 812 patients undergoing SP ablation for AVNRT, 659 patients (81%) had slow/fast form, 81 patients (10%) had slow/slow form, and 72 patients (9%) had fast/slow form. Radiofrequency ablation of SP eliminated AVNRT in all the 812 patients. According to the possible reentrant circuits to type different forms of AVNRT, 649 patients (80%) had slow/fast form, 10 patients (1%) had left variant slow/fast form, 57 patients (7%) had fast/slow form and variant fast/slow form, 15 patients (2%) had left variant fast/slow form, and 81 patients (10%) had slow/slow form. Conclusions There are good coincidences among electrophysiological properties, successful SP ablation sites and different forms of AVNRT typed according to the possible reentrant circuits. There is great significance using this new methodology to understand the reentrant circuits of AVNRT and to direct the ablation of SP for eliminating AVNRT.