Catheter ablation of idiopathic left fascicular ventricular tachycardia: Implications of false tendons for mapping and ablation.

INTRODUCTION: The anatomical substrate for idiopathic left ventricular tachycardia (ILVT) remains speculative. Purkinje networks surrounding false tendons (FTs) might be involved in the reentrant circuit of ILVT. The objective was to evaluate the anatomical and electrophysiological features of false tendons FTs in relation to ILVT.

METHODS: Intracardiac echocardiography (ICE) was conducted on patients with ILVT. The relationship of the FTs with ILVT was determined using electro-anatomical mapping.

RESULTS: Electrophysiological evaluation and radiofrequency ablation were conducted in 23 consecutive patients with ILVT. FTs were identified in 19/23 cases (82.6%) with P1 potentials during VT recorded at the FT in 14 of these patients (73.7%). Three FT types were identified. In type 1, the FT attached the septum to the base of the posteromedial papillary muscle (PPM) (4/19); type 2 FTs ran between the septum and the PPM apex (3/19), while in type 3, the connection occurred between the septum and apex (11/19) or between the septum and the LV free wall (1/19). The effective ILVT ablation sites were situated at the FT-PPM (3/19) and the FT-septum (16/19) attachment sites.

CONCLUSIONS: This series demonstrates the association between Purkinje fibers and FTs during catheter ablation of ILVT and verifies that left ventricular FTs are an important substrate in this type of tachycardia.