[Value of identifying the slow conduction zone of idiopathic left ventricular tachycardia by electroanatomic mapping].

Objective: To explore the value of identifying slow conduction zone(SCZ) of idiopathic left ventricular tachycardia(ILVT) by electroanatomic mapping.

Methods: Twelve patients with ILVT were mapped by a 3-dimensional electroanatomic (EA) mapping system. Left posterior fascicular potential (PP) and the SCZ with diastolic potential (DP) in LV during sinus rhythm (SR) and ventricular tachycardia (VT) were mapped after a three-dimensional endocardial geometry of the left ventricular was established. Then we investigated the electrophysiological and anatomic characteristics of SCZ.

Results: EA mapping was successfully performed in 9 patients during SR and VT, and in 3 patients during VT. The SCZ with DP was located at the inferoposterior septum, and the length of the SCZ was (25.1 ± 2.2) mm with a conduction velocity of (0.08 ± 0.01) m/s. There was no difference in these parameters between patients during SR and VT (P > 0.05). There was one area with PP located at the posterior septum. The areas with both DP and PP were found in 9 patients during SR and VT. In addition, this area was coincided with such area during VT during SR and radiofrequency ablation targeting the site within the area abolished VT in all patients.

Conclusions: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified by EA mapping and used to guide the ablation of ILVT.